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					Production Team
Carl Heltzel, Editor
Cornithia Harris, Art Director
Leona Kanaskie, Copy Editor
Michael Tinnesand, Contributing Editor
                                                                                         Question From the Classroom
                                                                                         By Bob Becker
Administrative Team
Terri Taylor, Administrative Editor
Sandra Barlow, Senior Program Associate
Peter Isikoff, Administrative Associate

Technical Review
Seth Brown, University of Notre Dame                              Q:    My parents are looking into buying a           gaseous molecules are then pushed closer
David Voss, Medina High School, NY                                                                                     together by a compressor, the intermolecular
                                                                  heat pump. A brochure they got said that in
Teacher’s Guide                                                                                                        forces can take over and cause the substance
William Bleam, Editor                                             the winter, a heat pump takes heat from the
Donald McKinney, Editor
                                                                                                                       to condense back into a liquid. This process
                                                                  cold outside air and pumps it into the house.
Mark Michalovic, Editor                                                                                                gives off heat; we say it is “exothermic” —
Ronald Tempest, Editor                                            In the summer, it pumps the heat from the
Susan Cooper, Content Reading Consultant                                                                               and that is the other half of the story!
David Olney, Puzzle Contributor                                   inside air out. How can it do that?                        So, imagine some CCl2F2 under enough
Division of Education                                                                                                  pressure that it is in the liquid state, and then
Mary Kirchhoff, Acting Director                                         A: As strange as this seems, that is fun-
Michael Tinnesand, Associate Director for Academic
                                                                                                                       have it injected into a compartment that is not
                                                                  damentally how a heat pump works, but the
Programs                                                                                                               at high pressure. The liquid would immediately
                                                                  truth is, your family already owns a heat pump
Policy Board                                                      — in fact they probably own three or four.           boil, taking in heat from the surroundings,
Doris Kimbrough, Chair, University of Colorado–Denver                                                                  making the compartment and the air around it
Ron Perkins, Educational Innovations, Inc., Norwalk, CT           Your refrigerator and air conditioners — both
Barbara Sitzman, Tarzana, CA                                      for your house and for your cars — are heat          get quite cold. Now move that gas through a
Ingrid Montes, University of Puerto Rico
Susan Gleason, Middletown, DE                                     pumps. They only work one way of course,             pipe and into a separate compartment where a
                                                                  but the principle is still the same.                 compressor increases the pressure and con-
ChemMatters (ISSN 0736–4687) is published five times a
year (Sept., Oct., Dec., Feb., and Apr.) by the American                So let’s take a look at how a refrigerator     denses it back into a liquid. This condensation
Chemical Society at 1155 16th St., NW, Washington, DC             works first. The explanation begins (as all          would release heat to the surroundings, mak-
20036–4800. Periodicals postage paid at Washington, DC,
and additional mailing offices. POSTMASTER: Send                  good explanations do) at the molecular level,        ing this compartment and the air around it get
address changes to ChemMatters Magazine, ACS Office of
Society Services, 1155 16th Street, NW, Washington, DC
                                                                  and what we will need is a substance with a          quite warm. Transferring this pressurized liq-
20036.                                                            boiling point about 50°C below room temper-          uid back into the low pressure compartment
Subscriber Information                                            ature. As you may have already learned, or will      allows this whole cycle to start again.
Prices to the U.S., Canada, and Mexico: $14.00 per sub-           soon, molecules are attracted to one another.
scription. Inquire about bulk, other foreign rates, and back
issues at: ACS Office of Society Services, 1155 16th Street,      In some substances the attractions are very
NW, Washington, DC 20036; 800-227-5558 or 202-872-
6067 fax. Information is also available online at
                                                                  weak, like between two H2 molecules. Because                  the attractions between H2 molecules are so
The American Chemical Society assumes no responsibility           weak, the substance is a gas at room condi-
for the statements and opinions advanced by contributors.         tions and must be taken to extremely low tem-
Views expressed are those of the authors and do not neces-
sarily represent the official position of the American            peratures before those attractions take over
Chemical Society. The activities in ChemMatters are intend-
ed for high school students under the direct supervision of
                                                                  and allow it to condense into a liquid. Its boil-
teachers. The American Chemical Society cannot be respon-         ing point is -253°C — way too low for our
sible for any accidents or injuries that may result from con-
ducting the activities without proper supervision, from not       purposes. In other substances, like H2O, the
specifically following directions, from ignoring the cautions     intermolecular forces of attraction are so                 This cycle takes place inside — and
contained in the text, or from not following standard safe lab-
oratory practices.                                                strong that the substance is a liquid at room        behind — your refrigerator, and although it is
All rights reserved. No part of this publication may be repro-
                                                                  temperature, and must be heated up quite a           called a “refrigerator,” it actually does as
duced, stored in a retrieval system, or transmitted in any form   bit to convert it into a gas. The boiling point of   much heating up as it does cooling down. Go
by any means, now known or later developed, including but
not limited to electronic, mechanical, photocopying, record-      H2O is 100°C–way too high. Some com-                 touch the metal grate on the back side of your
ing, or otherwise, without prior permission from the copyright    pounds though, known as refrigerants, have           fridge. The warmth you feel there is the heat
owner. Requests for permission should be directed in writing
to ChemMatters, American Chemical Society, 1155 16th St.,         just the right amount of intermolecular attrac-      released by the condensing refrigerant, and
NW, Washington, DC 20036–4800; 202-833-7732 fax.
                                                                  tions to give them the optimum boiling points.       indirectly it is the heat that has been
                                                                  Dichlorodifluoromethane (CCl2F2) — also              “pumped” out of your food and beverages!
                                                                  known as Freon-12 — is one such refrigerant,         The grate has a lot of surface area to allow
                                                                  and it has a boiling point of -30°C (room tem-       the heat to dissipate quickly. An air condi-
                                                                  perature is about 20°C).                             tioner works the same way: that big unit out-
       © Copyright 2006, American Chemical Society
                                                                        Now, when a substance boils, it changes        side your house is where the exothermic
           Canadian GST Reg. No. 127571347                        from a liquid to a gas; its molecules are pulled     condensation process occurs. And when
                    Printed in the USA
                                                                  away from one another, and the attractions           you’re trying to cool down an entire house
                                                                  between them are broken. This takes heat             full of air, heat dissipation becomes an even
                COVER ILLUSTRATION BY JIM NUTTLE                  energy in — we say the process is “endother-         bigger task. That is why there is a fan blowing
                                                                  mic” — and that’s half of the story of how a         air across the coils. Hold your hand over the
                                                                  refrigerator or heat pump works. If those            unit and feel the heat being pumped out of

2 ChemMatters, OCTOBER 2006                             
your house. Even when the outside tem-
perature is at its highest, the air blowing
out of that unit is hotter still. The boiling
(endothermic) side of the cycle is not
quite so accessible, but it is there —                                                                Vol. 24, No. 3                              OCTOBER 2006
inside your house, in the duct work with
the air being cooled as it blows across
the coils.
      So what exactly is special about a
heat pump? A heat pump is simply an air                                                           Question From the Classroom                                   2

conditioner that can be run in reverse. In                                                        How does a heat pump work?

                                                              MIKE CIESIE
the winter, with the refrigerant flowing the
opposite direction, the condensing now                                                            Glass: More Than Meets the Eye
                                                                                                  The sound of glass shattering. A scream in the night… Acts of
takes place inside your house and pro-
vides the warmth. Meanwhile, the boiling                                                          violence often involve broken glass and it's a common type of
is going on outside your house and mak-                                                           evidence found at crime scenes. How do forensic police match
                                                                                                  samples of glass?
ing the cold air out there even colder. Cool
gas enters the compressor which
increases the pressure (1). The gas, now                                                          ChemSumer
under high pressure, condenses into a liq-
uid making it very hot (2). Inside air is
                                                                                                  Chemistry Builds a Green Home
                                                                                                  It seems that everything is turning “green” these days. When
warmed as it blows across the warm liq-                                                           the concept is brought home, the results are impressive.
uid (3). As the warm liquid passes                                                                Today’s homes can be both environmentally friendly and
through an expansion valve (4), the pres-                                                         esthetically pleasing.
sure is allowed to drop. Under reduced
pressure, the liquid begins to boil and
gets very cold (5). The gas is now heated
                                                                                                  Sick Buildings—Air Pollution Comes Home
                                                                                                  When your parents tell you to go outside and get some fresh
by the outside air that is blown across the                                                       air, are they really doing you a favor? Take a look at the toxins
coils (6), and the process is repeated. As                                                        lurking around your home before you answer.
strange as this might seem, this method
of heating can be three to four times more                                                        ChemHistory
efficient than a conventional furnace, and
                                                                                                  The New Alchemy                                            15
                                                                                MIKE CIESIELSKI

thus with reduced energy bills, a heat
pump can essentially pay for itself over                                                          The elements from hydrogen to uranium were created in the Big
                                                                                                  Bang or afterward during the life cycles of stars, but what about
the years.
                                                                                                  the transuranium elements, those that lie beyond uranium on
      Furnaces generally produce heat the                                                         the periodic table? How were these artificial elements created
same way ovens do—either by burning                                                               and who were the men and women responsible for their
fuel (natural gas, propane, or oil) or by                                                         discovery?
passing high-voltage electricity through a
resistor. Neither of these is as efficient as                                                     Material Safety Data Sheets:
a heat pump. The one drawback, however,
to heat pumps is that they do not work as                                                         Passports to Safety?
                                                                                                  Next time you blow out a candle, will you be properly armed
well below 0°C. At such low temperatures,
                                                                                                  with a self-contained breathing apparatus and dry chemical fire
ice begins to form on the outside coils
                                                                                                  extinguisher? An MSDS is an important safety tool — but how
and this insulates them and prevents the                                                          do you gauge the accuracy of the information it contains?
heat from getting in. Many home-owners
are now installing dual systems: a heat

pump for the summer and for the mild
winter days, and a conventional electric                                                                         TEACHERS!

furnace that automatically switches on for
the occasional deep freeze.                                                                                 FIND YOUR COMPLETE
                                                                                                      TEACHER’S GUIDE FOR THIS ISSUE AT
Check out these great Web sites:

                                                                                                                                 ChemMatters, OCTOBER 2006 3
                More Than Meets the Eye
                                                 How do forensic                                   glass. The glass used in a picture frame is
                                                                                                   generally not subject to gusts of wind, so it
                                                 scientists match                                  will be thinner than glass used in a window.
By Brian Rohrig
                                                 samples of glass?                                 Glass used in a door is generally even
                                                       Careful observation can reveal subtle but   thicker, to withstand the forces applied as a
                                                 important differences between various types       result of frequent opening and closing (and
                                                 of glass. The forensic chemist may use sev-       sometimes slamming!).

             23-year-old single female is
                                                 eral methods for determining whether two
             awakened in the middle of the
                                                 samples of glass originated from the same
             night by an intruder standing                                                               One of the most common methods for
                                                 source. The first step is to visually examine
             over her bed. She screams. The                                                        matching glass samples is the determination
                                                 the glass. Physical properties of the glass are
             intruder flees in a panic, diving                                                     of density. The formula for density is
                                                 then measured. Subsequent steps involve
             through a closed window. The                                                          mass/volume, and the density of two pieces of
                                                 analysis of the chemical composition and dif-
police are notified immediately. They appre-                                                       glass will always be the same if they come
                                                 ferences in the way it was manufactured.
hend a suspect several blocks from the                                                             from the same source, regardless of the size
scene. He claims to be innocent, yet the         Physical                                          of the two pieces. The formula method for
police discover several shards of glass in the                                                     determining density involves measuring the
suspect’s hair and clothing. When these sam-     examination                                       volume of a glass sample of known mass. The
ples are compared to the glass of the broken           Some important features to note are         volume can be determined by displacing water
window, they are discovered to be the exact      edge thickness, color, and the presence of        in a volumetric flask.
same type of glass. On the basis of this evi-    any labels or imprints on the glass. A black-           Another more accurate method of com-
dence, the intruder is eventually convicted      light lamp may be used to check for repairs       paring densities is the flotation method. A
and sent to jail.                                as hairline cracks will glow under ultraviolet    sample of glass is dropped into and sinks to
      Because acts of violence often involve     light. Modern paints will also glow under a       the bottom of a liquid containing an exact vol-
broken glass, glass is one of the most com-      blacklight.                                       ume of a dense liquid, such as bromobenzene
monly encountered forms of evidence found                                                          (d = 1.52 g/mL). Then, a denser liquid, such
at crime scenes. However, many pieces of         Thickness                                         as bromoform (d = 2.89 g/mL) is added drop-
glass appear identical to the naked eye even           Glass thickness is generally a function     wise until the piece of glass rises up from the
though they can differ markedly in their chem-   of its application. Glass from a light bulb is    bottom and attains neutral buoyancy. Neutral
ical composition.                                going to be thinner than a pane of window         buoyancy occurs when an object has the exact

4 ChemMatters, OCTOBER 2006            
                                                                                                                                                            86.5 mL
                                              81.0 mL

                                                                                                                                                                           MIKE CIESIELSKI
                   The formula method for determining density: After finding the mass of an object, measure its volume by water displacement.

                same density as the surrounding fluid, and           Refractive index                                             Glycerin has a refractive index of 1.473.
                neither sinks nor floats but is suspended in                                                                If a piece of glass seems to dissapear in glyc-
                one place beneath the surface of the fluid.                Another very accurate method used to             erin, then it too has a refractive index of
                     The same procedure is then performed            compare samples is to determine their index            1.473. If two samples of glass have the same
                with another piece of glass, and if the volume       of refraction, or refractive index. Any object         refractive index, this does not necessarily
                needed to attain neutral buoyancy is the same        that transmits light has its own refractive            prove they are from the same source. But if
                as for the first sample, then the densities of       index, which is a measure of how much the              two samples have different refractive indexes,
                the two samples are equal. The exact density         object slows the speed of light. When light            they are definitely not from the same source.
                of each sample can be calculated by using the        passes through any medium, it is slowed                The FBI has a database of refractive index val-
                following formula:                                   down. The denser the medium, the slower the            ues for approximately 2000 different types of
                                                                     light travels. The refractive index of any sub-        glass, allowing forensic scientists the ability to
                           d = X(2.89) + Y(1.52)                     stance is a ratio of the velocity of light in a        identify samples. The most common value for
                                                                     vacuum to the velocity of light in that particu-       the refractive index of glass is 1.5180.
                                       X+Y                           lar medium. For example, the refractive index
                                                                     for water is 1.33. This means that light travels
                      X and Y refer to the volumes of the            1.33 times faster in a vacuum than it does in
                respective liquids, with the numbers in paren-       water. And when light passes from one
                theses referring to the densities of each liquid.    medium to another one with a different refrac-
                Any two liquids can be used, as long as they         tive index, refraction (or bending) of the light
                are miscible in one another and have appro-          occurs. This is why objects appear bent or
                priate densities. But when determining the           distorted under water.
                density of glass, liquids with a relatively high           Every liquid has its own refractive index.
                                                                                                                                                                                             MIKE CIESIELSKI

                density must be used, since glass is always          If a piece of glass is placed in a liquid with a
                denser than water. The density of a typical          different refractive index, an outline of the
                piece of single-pane window glass ranges             glass is clearly visible—known as the Becke
                from 2.47 to 2.56 g/mL. If the density of a          line. However, if a piece of glass is placed in a      The beaker on the left contains water and the
                1.5-g sample of glass were 2.48 g/mL, what           liquid with the same refractive index, the             one on the right, glycerin. Both beakers also
                would you predict the density to be for a 3.0-g      Becke line will disappear and the glass will           contain a glass stirring rod. Because the glass
                                                                                                                            rod and glycerin have the same refractive index,
                sample of the same glass? (Find the answer           seem to disappear. This is because the glass           the glass rod in the beaker on the right seems
                at the conclusion of this article.)                  bends light at the same angle as the liquid.           to “disappear.”

                                                                                                                                     ChemMatters, OCTOBER 2006 5
Chemical                                                                                                                                 paring the size of the
                                                                                                                                         exit and entrance
composition                                                                                                                              holes of each bullet,
      If both the density and refractive index of                                                                                        it can be determined
two samples of glass are the same, then the                                                                                              who fired first.
final test will involve sophisticated methods to                                                                                               The direction
determine their chemical composition. The                                                                                                from which a bullet
difference between types of glass can be due                                                                                             was fired can be
to the chemical composition of the glass itself                                                                                          determined by com-
or differences in how the glass was manufac-                                                                                             paring the size of the
tured. Most glass is made from silicon dioxide                                                                                           entrance hole to that
(SiO2), the primary ingredient in sand, which                                                                                            of the exit hole. Exit
has been heated above its melting point of                                                                                               holes are always
1600°C. Various substances are then added,                                                                                               larger, regardless of
depending on what type of glass is desired.                                                                                              the type of material

      Different additives can impart different                                                                                           through which a bul-
properties to the glass. Sodium carbonate or                                                                                             let penetrated.
soda (Na2CO3) is added to the silicon dioxide         A bullet hole in window glass.                                                     Because glass is
during glassmaking, lowering both its viscos-                                                                                            elastic and bows
ity and melting point. The soda increases the          impact originated. Radial fractures look like          outward when struck by a bullet, a larger
water solubility of SiO2, making it much easier        spider webs that spread outward from the               piece of glass will be knocked out on the sur-
to fashion into glass. Calcium oxide or lime           impact hole. Concentric fractures form next,           face where the bullet is leaving as opposed
(CaO) is added next, restoring water insolubil-        and these lines encircle the bullet hole. Con-         to the very small hole the bullet makes when
ity to the mixture. As a result of these two           centric fractures always start on the same side        it enters.
additives, most glass used to make windows             as that of the destructive force.                            Because of its elasticity, glass always
or bottles is known as soda-lime glass.                      A radial fracture will always terminate          blows back in the direction the impact origi-
      Boron oxide (B2O3) is used to make               into an existing fracture (see illustration). If       nated. Because of the violent tendency of
Pyrex glassware. The beakers and test tubes            there is a second bullet hole in a piece of            glass to snap back after being stressed, it can
you use in chemistry lab are most likely made          glass, its radial fractures will always terminate      blow back glass several meters in the direc-
from Pyrex, as is the glass used to make auto          into the cracks from the first bullet hole. The        tion from which the shot originated. If a bullet
headlights. Glass made with boron oxide                radial cracks from a third bullet will terminate       strikes a window from the outside and shat-
expands and contracts very little when heated          into the radial fractures from the second bul-         ters it, most of the glass will be on the out-
and cooled, which is why Pyrex glassware can           let, and so forth. The sequence of numerous            side. This piece of information can be
be heated and then cooled without breaking.            bullet holes can be determined by this                 extremely valuable in determining from which
      To make eyeglasses, a very sturdy glass          method. If the glass is shattered, it may be           direction a shot was fired.
is desired, so the additive potassium
oxide (K2O) may be used. This                                                                                 Was the light on
                                                     concentric                        radial
imparts hardness to the glass. Other
metallic oxides can give glass a spe-                                                                         or off?
cific color. Copper and cobalt oxides                                                                               Here’s a bit of information that can be
are used to make glass blue, man-                                                                             valuable in crime scenes involving a broken
ganese oxides give glass a purple                                                                             incandescent bulb, especially among vehicle
color, and lead-antimony oxide                                                                                collisions. It is easy for someone to drive at
imparts an opaque yellow.                                                                                     night with their lights off while driving down a
                                                                                                              well-lit street. But suppose you’re cruising
Who fired first?                                                                                              down the road one night, and bam! You get
       When a bullet strikes a pane of                                                                        into an accident with a motorist who did not
ordinary window glass, careful obser-                                                                         have his lights on. If it could be proven that
vation can reveal several crucial          The sequence of shots can be determined: the radial fractures of   the other motorist failed to turn on his head-
details. First of all, glass has a certain the second hole terminate in those from the first hole.            lights, this would be a big boost to your case.
degree of elasticity and will break                                                                           But suppose it is his word against yours. By
when this elastic limit is exceeded. This elas-        necessary to reconstruct the broken pieces             examining the broken filament of a light bulb,
ticity produces the familiar pattern of concen-        first. There has been more than one case of a          it can easily be determined whether the bulb
tric and radial fractures that accompany               shootout ensuing through the windshield of a           was on or off when it was broken.
penetration of glass by a projectile. The radial       car between a police officer and a suspect. By               Light bulbs do not actually burn, but
fractures are produced first and always form           examining the termination lines of the radial          rather, glow as the tungsten filament becomes
on the side of the glass opposite to where the         fractures from each bullet hole and by com-            very hot due to the resistance that the elec-

6 ChemMatters, OCTOBER 2006                  
trons encounter as they pass through the very
narrow wire filament. The definition of incan-
descence is the property of emitting light as a
result of being heated, but not actually burn-
ing. The electrons in the filament material
absorb energy and jump to higher atomic
orbitals (excited state). They then release a
photon as they fall back to their original
                                                       Here is another cool
ground state orbital. In a properly functioning        activity involving glass.
light bulb, the glowing filament is inside of the
bulb filled with a noble gas such as argon.
                                                       approved protective eyewear
      But if the filament is glowing when the
bulb is broken, it will immediately react with         paper towels
oxygen in the air and break in half. This will         (2) 10-mL graduated cylinders
form a thick layer of yellowish-white tungsten         1 glass stirring rod

                                                                                                                                                                 MIKE CIESIELSKI
oxide on the filament due to the reaction of           glycerol (about 10 mL)
the tungsten with oxygen. If the presence of           water (about 10 mL)
tungsten oxide on the filament is found, then
it can be proven that the bulb was on when                            Wear your safety goggles during this activity,
the accident occurred. The absence of tung-                             and do not taste any of the liquids used.
sten oxide on the filament reveals that the
bulb was probably off when it was broken.                 1. Obtain a glass stirring rod from your teacher.

Solving the crime                                         2. Place about 8 mL of glycerol in a 10-mL graduated cylinder and 8 mL of
                                                             water in another 10-mL graduated cylinder.
      Sometimes, a bit of deductive reason-
ing is all it takes to solve a crime. In 1988,            3. Put the stirring rod into the graduated cylinder with the water in it.
there were dozens of claims by consumers
                                                          4. Record your observations.
that they had found shards of glass in jars of
Gerber baby food. After forensic investiga-               5. Remove the stirring rod and dry it off with a paper towel.
tors examined these contaminated jars, they
                                                          6. Now place the rod in the graduated cylinder containing the glycerol. What
discovered many different types of glass—
glass from mirrors, bulbs, and car head-
lights were all found. If the glass came from             7. Record your observations.
the manufacturing plant due to an accident
such as a light bulb breaking over the pro-               After discussing this activity with your small group, devise an explanation
duction line, then you would expect to find            for what you observed. Be prepared to share this with the class.
only one type of glass in the jars, not sev-
eral. It was therefore concluded that the
glass found in the jars of baby food was a          REFERENCES
result of deliberate tampering.                     Ellis, W. S., Glass. Avon Books: New York, 1998.
      The field of forensic science provides a      Fisher, D. Hard Evidence. Dell: New York, 1995.
fascinating glimpse into how science can be         Saferstein, R. Criminalistics: An Introduction to Forensic Science. Pearson Prentice Hall: Upper
used to solve crimes. A well-trained forensic           Saddle River, NJ, 2004.
scientist uses aspects of biology, chemistry,
                                                    INTERNET RESOURCES
physics, and mathematics to reconstruct what
                                                    Automobile Window Glass—A Design Defect That Should Not Be Overlooked,
may have happened at a crime scene. Crimi-
nals may break society's laws, but they cannot      Bullets Out, None In,
break the laws of nature.                           Different Types of Glass,
Answer to question:                                 How does safety glass work?,
     The 3.0-g sample of glass has the same         Tempered Glass Breakage,
density as the 1.5-g sample. It might be twice      What makes glass transparent?,
                                                    What’s That Stuff? Glass,
as massive, but then it has twice the volume.
Since density is M/V, the density of both
pieces would be identical. Remember, density
                                                    Brian Rohrig teaches at Jonathan Alder High School in Plain City, OH. His most recent ChemMatters article,
does not depend on the size of the sample!          “The Chemistry of Digital Photography and Printing”, appeared in the February 2006 issue.

                                                                                                                     ChemMatters, OCTOBER 2006 7

Forensic Identification of
Glass Activity
     As the article on glass points out, it is relatively common to find pieces
of broken glass associated with crime scenes. Forensic scientists are often
asked to determine the origin or prove the identity of various samples of
glass shards.
                                                                                        Placing pieces of plastic in isopropanol.
Finding the Density of Glass:
     Because the liquids mentioned in the article are not considered safe for
routine high school use, here’s an alternative method that will demonstrate
the same concept.

Before you begin, answer these questions:
   1. If you place small bits of plastic in water, will they float or sink? Will
      they float or sink in rubbing alcohol? What information would you
      need to know in order to make a prediction?
     2. If you used a much larger piece of the same type of plastic, would it
        affect whether or not it floats in the liquids?
     3. If a piece of plastic sinks in a liquid, what does that mean about the
        density of the plastic relative to the density of the liquid? In terms of
        the density of plastic relative to the density of the liquid, what does it      Carefully adding water until the pieces of plastic begin to rise.
        mean if the plastic floats?

    approved protective eyewear
    100-mL graduated cylinder
    small pieces of plastic from a pen top
    100-mL beaker
    10-mL graduated cylinder
    isopropanol (rubbing alcohol, 70%)
    dropper pipet

     Be sure to wear safety goggles while completing this activity.
     Do not taste any of the liquids used in this activity.
                                                                                                                                               MIKE CIESIELSKI

     Your teacher will provide you with pieces of plastic that have come
from ordinary ballpoint pens. Use a balance to determine their mass; record
the mass as accurately as possible. Place 50.0 mL of isopropanol in a 100-
                                                                                         At this point, the densities of the plastic and the
mL beaker. Add water slowly until the plastic pieces begin to rise. Record               solution are the same.
the exact amount of water needed to get the plastic pieces to attain neutral
bouyancy; that is, they stay suspended about half way to the top of the liquid
     Using the equation from the article, calculate the density of the plastic.

8 ChemMatters, OCTOBER 2006                 

                                          Chemistry Builds a
                                             GREEN HOME
Reduce, Reuse,
By Roberta Baxter

                                          building industry

        ou probably learned that slo-
        gan in first grade when you       toward high-perfor-
        celebrated Earth Day. But         mance, sustainable
beyond recycling aluminum cans            practices. Certain crite-
and newspaper lies the building of        ria are used in giving a
an environment-friendly home.             home-building project
Builders across the country are com-      the “green building”

                                          label, using a common

peting to design and build green
homes. Not greenhouses, for grow-         standard of measure-
ing plants—green homes, meaning           ment. For example,
environmentally responsible homes         homebuilders can earn
and construction practices. The idea      points by these actions,
is to reduce waste in the building        along with others:
process, create energy-efficient,           • reducing construction waste to          Reduce
water-saving homes, and promote               less than 2.5 pounds per square               The residential construction
the use of sustainable materials.             foot of home;                           industry generates 58 million tons of
       Sustainability is a hot buzzword     • reducing energy costs by using          waste per year, according to a study
in the “green” arena, but what does it        efficient appliances;                   conducted for the EPA. Home reno-
mean? The U.S. Environmental Pro-           • building a well-insulated               vation projects account for 55% of
tection Agency (EPA) defines sus-             structure;                              the waste, demolition accounts for
tainability as “the ability to achieve      • installing energy-efficient lighting,   34%, and new construction accounts
continuing economic prosperity                heating, and cooling systems;           for 11%. Any reduction in the
while protecting natural systems of           and                                     amount of this waste is a step in the
the planet, providing a high quality of     • reducing water usage with high-         right direction.
life for its people.” This calls for          efficiency toilets and natural
everyone taking responsibility for            landscaping.
solving the problems of today and               Homes receiving the highest
caring for the planet for the genera-     number of points receive a platinum
tions of tomorrow.                        rating, followed by gold, silver, and
       The U.S. Green Building Council    certified ratings. The USGBC hopes to
(USGBC) has created a pilot program       increase consumer awareness of the
called LEED, or Leadership in Energy      benefits of green building, stimulate
                                                                                                                              JIM NUTTLE

and Environmental Design. The pro-        green competition, and transform the
gram is an effort to move the home-       practices of the building industry.

                                                                                                               ChemMatters, OCTOBER 2006 9
      One of the biggest costs of homeowner-                                                  A home in New Mexico was chosen as
ship is energy. The chemical company BASF                                               the VISION House 2006 for Green Builder
sponsored the construction of a Near-Zero-                                              Magazine. This is one of over 1 million homes
Energy home in Paterson, NJ. The home was                                               using a geothermal system to reduce the cost
built with concepts developed by the Oak                                                of conditioning indoor air. The concept behind
Ridge National Laboratory in Oak Ridge, TN,                                             a geothermal heating system is to use the heat
and PATH/Build America, the Partnership for                                             energy of the earth to moderate the air tem-
Advancing Technology in Housing. The                                                    perature in our homes: geo (earth) + thermal
demonstration home is claimed to be 80%                                                 (heat). Over most of our planet, the top 10
more energy efficient than a typical home. On                                           feet of the surface stays consistently in the

                                                                                                                                                                                                                CESAR CAMINERO
sunny days, the home could easily produce                                               50–60 °F range (10–16 °C). That means there
more energy than it uses. It is also more                                               is a giant, mostly untapped heat and power
durable, has a lower environmental impact,                                              source right below our feet.
and is faster to construct than conventionally                                                A geothermal system runs a refrigerant                         Low-E windows are spectra-selective; they
                                                                                                                                                             allow selected portions of the solar spectrum to
built homes.                                                                            or a water and antifreeze mixture through                            pass through while restricting others.
      Rather than using wood studs and siding                                           pipes buried in the ground below frost depth.
for the walls, the Near-Zero-Energy home was                                                                   A pump and compressor                     blocking transmission of the infrared, or
constructed with foam-insulated concrete                                                                       circulate the mixture                     “heat” radiation. Low-E windows are more
forms. These are rigid plastic foam forms that                                                                 through a heat                            insulating than normal windows because they
hold concrete in place while it hardens, and                                                                   exchanger. In the winter,                 reduce radiative heat transfer. They cut down
they remain in place afterward to offer extra                                                                  when the temperature                      on solar heat gains in the summer and pre-
thermal insulation. The foam insulation keeps                                                                  underground is warmer                     vent loss of interior heat in the winter.
heat and cold out of the house by trapping air                                                                 than the surface, the
in the holes of the foam. Air is a very poor                                                                   thermal energy of the                     Reuse
conductor of heat, which makes it a good                                                                       earth is drawn up                               The “reuse” part of the slogan also
resistor, impeding the flow of heat. Note that                                                                 through the pipes,                        comes into play in green homes. Contractors
it's not the plastic foam (or in other cases,                                                                  moved into the home,                      are working hard to reuse pieces of wood and
fiberglass, stone, wool, or feathers) that slows                                                               and is allowed to dis-                    drywall to cut their costs during new home
the heat loss, but the air that’s trapped in                                                                   perse into the rooms.                     construction. Several companies reclaim old
between the layers of an insulating material.                                                                  Usually, duct fans dis-                   wood from demolished houses, buildings, and
      The concrete form technique is quicker                                                                   tribute the heat through-                 barns. Some lumber is even dredged up from
than building a traditional block foundation,                                                                  out the house. The                        river bottoms where logs have sunk during
and the concrete can be poured and allowed                                                                     process is reversed in                    logging operations. The wood is cut and
to harden in more extreme climates than nor-                                                                   the summer when the                       sanded and fashioned into wood flooring.
mal poured concrete. Concrete is an artificial                                                                 ground temperature is                     Using the hardwood from these reclamations
stonelike material that is made by mixing wet                                           cooler than the surface, helping to cool the                     saves trees and reuses wood that would oth-
cement, sand, and gravel together. The                                                  house. Unwanted heat is concentrated, sent                       erwise be headed for landfills.
cement gradually sets, binding the other com-                                           on down the line and absorbed by the earth,
ponents together to give the rock-like material                                         while cool air is returned.
you are familiar with. Using concrete for the                                                 Geothermal systems are quiet and, com-
structure eliminates the need to cut down                                               pact, and they emit no gases so they can be
trees—a green advantage.                                                                placed indoors. A side benefit is that they pro-
                                                                                        vide inexpensive hot water throughout the
                                                                                        summer. Best of all, the heat source is renew-
                                                                                        able—a sustainable system that uses no fossil
                                                                                                                                           MIKE CIESIELSKI

                                                                                        fuels and emits no greenhouse gases.
                                                                                              In the early 1990s, the U.S. Department
                                                                                        of Energy contributed significantly to the
                                                                                        development of low-E window coatings. Also                             An unusual application is kitchen and
                                                                                        referred to as low-emissivity, these windows
                                                   COURTESY OF GREEN BUILDER MAGAZINE

                                                                                                                                                         bath cabinets made from wheat straw. The
                                                                                        use tin or silver metallic oxides that greatly                   straw is a waste product from agriculture.
                                                                                        reduce the amount of energy needed to heat                       Wheat heads are cut off the plant, leaving the
                                                                                        or cool a home. The coatings can be applied                      stems behind. The chopped straw is glued
                                                                                        into the molten glass, sprayed on, or added as                   together with nonformaldehyde containing
                                                                                        a thin film pressed between layers. The win-                     adhesives and pressed into shape. The cabi-
                                                                                        dows are designed to be solar selective,                         nets look and feel just like wood, and they are
Vision House 2006 in Albuquerque, New Mexico.                                           admitting as much daylight as possible while                     produced from 85% renewable materials.

10 ChemMatters, OCTOBER 2006                                                  
Recycling is a vital part of any green home.
                                                         Representatives of the carpet industry esti-
                                                         mate that 3.5 billion pounds of carpet
                                                         waste goes to landfills each year. Mostly,
                                                                                                               Ways To
Environment-friendly contractors search for
materials that have been recycled and those
that can be easily recycled at the end of
                                                         it is old carpet that cannot be reused, but
                                                         industry giants DuPont and Antron are
                                                         implementing carpet-recycling programs. If
                                                                                                               Be Green
their use.                                               carpet can be cleaned and reused, it is                      Many techniques for being green
      One popular product made from recycled             donated to charity or sold. If reuse is not            were presented to you way back in
materials is carpet. About half of the polyester         possible, the carpet is recycled into new              first grade or were offered by your par-
carpet in the United States is                                               plastic products, such as          ents. Here are a few ideas:
made from recycled plastics.                                                 filtration devices, furniture,
It takes five two-liter bottles                                              and automotive parts.               1. Turn off lights and electronics
to make one square foot of                                                          Another homebuilding            when not in use.
carpet, so there might be 500                                                material that is often made         2. Recycle anything possible: paper,
recycled bottles on your liv-                                                of recycled plastic is com-            aluminum, glass, and plastic.
ing room floor.                                                              posite lumber. Used for
      Plastics are synthetic                                                 decks and window and                3. Close curtains on sunny summer
polymers, and polymers are                                                   door frames, this material             days and open them on sunny
long chains of repeating mol-                                                is a 50/50 mixture of wood             winter days.
ecules linked together (“poly”                                               fibers from sawdust and             4. Buy energy-efficient appliances
                                                                         MIKE CIESIELSKI

means many, and “mer”                                                        recycled plastic. The wood             and electronics when possible.
means unit, or part). The typ-                                               fibers reinforce the plastic
ical two-liter bottle is made                                                lumber, so that it is               5. Use appliances wisely; for exam-
of a polymer called polyethyl- Recycling: part of Green Living              stronger than 100% recy-                ple, it’s usually more efficient to
                                   includes sustainability, taking                                                  heat with a microwave than an
ene terephthalate, or PET for                                               cled plastic. Furthermore,
                                   responsibility for the protection of                                             oven, and run clothes and dish-
short. You might have seen         our natural resources.                   the plastic protects the
this familiar logo on the bot-                                              wood from rotting. So the               washers only when full.
tom of some plastic prod-                                combination of natural and synthetic materi-            6. Set thermostats
uct. PET is a thermoplastic,                             als brings out the positive characteristics of             at 68° in win-
meaning it can be repeat-                                both wood and plastic.                                     ter and 72°
edly reheated and reshaped.                                     A huge advantage for the homeowner is               in sum-
Once a bottle is used, it can                            that plastic lumber does not have to be                    mer.
be recycled by cutting it                                painted. Color can be added during the man-
into pieces, then cleaning                               ufacturing process. As a further blessing to            7. Caulk
and remelting the pieces. Once it has been               the environment, composite lumber is made                  around
warmed, the plastic can be either molded to              of plastic and sawdust that would otherwise                doors and
make new bottles or spun into fibers to make             end up in a landfill.                                      windows.
items such as carpet and even clothing.                         Glass winds up in landfills about as             8. Use fluorescent
      PET is made via a condensation reaction,           often as plastic, and concrete waste places a              light bulbs.
in which molecules are joined together while a           huge burden on landfills. Kitchen counter-
molecule of water is split out.                          tops for the VISION 2006 house were made                9. Drink tap water rather than
      Another important aspect of the carpet             from 75% recycled concrete and glass. The                  bottled water.
story is keeping old carpet out of landfills.            material looks like natural stone.                     10. Use indoor plants like Golden
                                                                                      As homebuilders               pothos or English ivy to remove
                                                                               and the public become                indoor air pollutants.
                             +                                                 more aware of the possi-
                                                                               bilities of building green       11. If you are an outdoor gardener,
                                                                               homes, more innovative               use ladybugs rather than chemi-
                                                                               products will come along.            cal insecticide to get rid of plant-
                                                                               Your next home may be                eating insects.
                                                                      +        green enough to save
                                                                    n          thousands of dollars in
                                                                               construction and mainte-
                                                                               nance costs. Just think
                                                                               what you could do with
                                                                                                              Roberta Baxter is a science writer who lives in
The condensation reaction that forms polyethylene terephthalate (PET).
                                                                               that green!
                                                                                                              Colorado Springs, CO. Her most recent ChemMatters
PET is a polyester polymer; one of the ester groups is highlighted.                                           article, “Battling Zits”, appeared in the April 2005 issue.

                                                                                                                           ChemMatters, OCTOBER 2006 11

                                                                                                         By Michelle Laliberte

                                                                    cally. With poorer circulation, chemicals         radiation contamination, and it showed radon
                “Why don’t you go                                   released inside the home could build up to        levels 650 times the average level. Radon is a
                play outside and get                                potentially dangerous levels. Now, growing        naturally occurring radioactive gas that is a
                                                                    public awareness of indoor air pollution has      byproduct of decaying uranium and a known
                some fresh air?”                                    given birth to new terms such as “indoor          cause of lung cancer. His family, including
                                                                    environmental health” (IEH), and “sick build-     small children, was immediately evacuated.
                                                                    ing syndrome” (SBS). But news reports may         High radon levels were also found in nearby

                          ow many times have you been told
                          this? You might have thought this         sometimes go too far, sensationalizing the        houses. Stanley’s home is on the Reading
                          was just a way to get you out of your     subject to the point of scaring the daylights     Prong, a region that stretches from Reading,
                          parents’ hair for a while. But there      out of us. Should we be worried? What should      Pennsylvania through New Jersey and into
                might be some sound chemical reasons to             you do?                                           New York. This granite formation has very
                spend some time outside of the house. That’s                                                          high deposits of low-grade uranium.
                because air pollution can sometimes be a real       Sources of indoor
                problem—inside the home!                                                                              Radon
                      All kinds of activities that take place       air pollution                                           Radon-222 is produced by the natural
                inside the home can release chemicals or par-             Stanley Watras lived in Boyertown, PA       disintegration of the radioactive element
                ticles into the air. Some are obvious, such as      and worked at the Limerick Nuclear Power          radium-226. Radium itself is produced by the
                using an aerosol deodorant or painting a            Plant. During December of 1984, Stanley set       decay of uranium-238, which is found in rock
                room. Some are less obvious, like taking a          off alarms at the plant as he attempted to        layers and bedrock. It is present in most of
                shower, frying food, or rolling on the new          enter through portal radiation monitors. Every    the soil and rock around the world, especially
                plush carpet with your pet dog. In drafty old       day for two weeks Stanley went through            areas with lots of granite, shale, and phos-
                buildings, this was not a big problem, because      decontamination while the authorities at the      phate rock.
                there was enough ventilation to prevent these       nuclear power plant tried to find the source of         With the loss of an alpha particle, radium
                substances from building up. But to bring           his radiation contamination. It was confusing     is converted to radon gas. Radon itself is not
                fresh air into a building and heat it in the win-   because the power plant was not yet produc-       harmful. It is chemically inert (it’s a noble gas
                ter or cool it in summer costs money. In            ing fission products, but the contamination       after all) and has a short half-life of only 3.8

                response to the energy crisis in the 1970s,         source was eventually found.                      days. However, Rn-222 undergoes radioactive
                builders started sealing up homes and office              It was coming from Stanley’s house. At      decay to form polonium-218, which in turn
                buildings and air circulation decreased drasti-     Stanley’s urging, his home was tested for         undergoes decay in a continuing chain termi-

                12 ChemMatters, OCTOBER 2006              
        Several decay       Loss of alpha                                                                                      find particleboard all through a home as
            steps             particle                                                                                         subflooring and shelving. The formaldehyde
    U       ➞           226
                            Ra   ➞          222
                                                Rn                                                                             reacts chemically with urea or phenol to form
                                                                                                                               a resin that binds the materials of particle-
Uranium-238             Radium-226          Radon-222                                                                          board together. Formaldehyde reacts with
                                                                                                                               phenol to form 2,4-dimethylol phenol (A).
nating in stable Pb-206. These progeny nuclei                                                                                  This compound reacts with 2-methylol phenol
are charged and chemically reactive, so they                                                                                   (B) in a condensation reaction to form com-
attach to airborne dust particles that can be                                                                                  pound C. A condensation reaction is one
inhaled into the lung. Several of the progeny                                                                                  where two reactants are joined together as a
are alpha-emitters; when they undergo decay,                                                                                   small molecule is split out; in this case, the
the energetic alpha particles blast into and                                                                                   small molecule is H2O. Compound C poly-
damage the surrounding cells.                                                                                                  merizes to form the resin known as Bakelite,
       Because radon is a gas, it can permeate                                                                                 which sets, or hardens, binding particles

                                                                                                         MIKE CIESIELSKI
your house through the basement or crawl                                                                                       together.
space or through exposed soil and rock                                                                                                When the polymer resin forms and the
beneath and around your home’s foundation.           Test kits for radon and CO are commercially                               material sets, there is not supposed to be any
Sometimes, it can seep in through well water,        available.                                                                formaldehyde left; it should have all reacted.
or migrate into your home through natural                                                                                      The problem comes from small amounts of
gas lines.                                           problem, and now Stanley is successfully                                  unreacted formaldehyde that gets entrapped
       In order to measure and report an             working in the radon mitigation field!                                    in the resin and is released over time. The
amount of radiation, we need a standard unit;                                                                                  release, or outgassing, of the excess
the standard measure for the intensity of            Formaldehyde                                                              formaldehyde is gradual, occurring rapidly at
radioactivity of some radioactive substances                Formaldehyde (CH2O) is a volatile and                              first and then slowing over time. Thus, expo-
is the curie (Ci). The curie is a measure of the     flammable organic chemical that can be                                    sure is greater in a new home furnished with
number of atoms in a collection of atoms that        released into the air as a pungent, suffocating                           new products.
are giving off radiation per an interval of time.    gas. It is naturally produced in our bodies in                                   Formaldehyde is a potent eye, upper
Radium decay is used as the basis for the            very minute quantities as part of normal                                  respiratory and skin irritant. Exposure causes
curie, and one gram of Ra-226 gives off 2.2          metabolism. We are exposed to formaldehyde                                central nervous system problems, including
trillion decays per minute. A curie is a lot of      in the air, food, and in cosmetic products.                               headaches, fatigue, and respiratory depres-
radiation, so we routinely speak of radiation        Known by its other names methanal, methyl-                                sion. It has the potential for inducing asth-
intensity in terms of a picocurie. Pico is a         ene oxide, and formalin (a 37% mixture in                                 matic attacks and recent epidemiological
prefix meaning one trillionth, or 10-12, so a        water), formaldehyde is one of the top 25                                 studies of work-exposed individuals suggest
picocurie (pCi) is equal to 2.2 disintegrations      most abundantly produced chemicals in the                                 that formaldehyde causes nasal cancer. To
per minute.                                          world. It is used as a disinfectant, preserva-                            minimize your exposure, buy solid wood
       Back to radon—the EPA has set safe            tive, fire retardant in foam insulation, clothing,                        furniture when possible, and keep your home
limits for indoor radon at 4 picocuries per          paper products, carpeting, and—yuck—                                      properly ventilated.
liter of air (4 pCi/L). The average indoor level     embalming fluid. Formaldehyde is added to
of Ra is 1.3 pCi/L, and about 0.4 pCi/L is nor-      cotton products to give
mally found in air outdoors. The level of            them wrinkle-resistance,
                                                                                                                               CH OH
radon gas in Stanley’s (remember Stanley?)           and is added to many                      + 2               H             +                       2

home was an astonishing 415 pCi/L, a level           more products, including                                                      2,4-dimethylol phenol
                                                                                      phenol        formaldehyde
that has been estimated to carry a risk equiv-       (believe it or not) Italian                                         CH OH             2

alent to smoking 135 packs of cigarettes per         cheeses, fish, dried                                                  A
                                                                                                                                    OH                       OH
day. In fact, this level of radon far exceeds        foods, and toothpaste.             OH                                                               CH     CH
                                                                                                                             CH           CH                               2           2
                                                                                                            OH                                     2               2
                                                                                              CH OH
that allowed in uranium mines!                              When combined                      2
                                                                                                                 CH OH             2
       Radon gas problems can be corrected           with urea or phenol,
                                                                                                                                  HC               CH        CH                    2
(mitigated) by increasing ventilation through-       formaldehyde makes an              CH OH
                                                                                          2    -H O
                                                                                                                                                           2           2

                                                                                        +          2
out the house, especially in the basement.           excellent adhesive resin,                                             2
Sealing cracks and openings in the foundation        so it is widely used in the                                             CH            CH      2      CH       2           2

can also help to keep some of the radon out.         building and furnishings                                    CH OH             2
                                                                                              CH OH
                                                                                               2                                           OH
You can't smell it, so to be safe, all homes         industry. The construc-                                OH
                                                                                       OH                              CH            CH2
should be tested for radon gas levels; com-          tion of pressed-wood               B                   C                                                  2

mercial test kits are available at many hard-        products such as parti-                                            HO
ware stores. So, what happened to Stanley            cleboard often involves                                                HC                 2

Watras? He and his family eventually moved           the use of formaldehyde-
                                                                                   The formation of a polymer resin used for particleboard. Formaldehyde is a
back into the home after fixing the radon            based resins. You can         key reagent.

                                                                                                                                           ChemMatters, OCTOBER 2006 13
Molds and biological                                                   Keeping mold growth under control is accom-
                                                                       plished by making sure basements, bath-
pollutants                                                             rooms, and other rooms are clean and dry.
      Molds, mildew, fungi, bacteria and house                         Chlorine bleach will remove any visual mold
dust are some of the main biological pollu-                            and can be used to clean out humidifiers and
tants in the home. Spores generated from                               air-conditioning condensing units. Use vacu-
mold and mildew are released into the air and                          ums with high-efficiency filters and consider
form new colonies wherever they land. Areas                            replacing old carpet with hard surface flooring
of the home with high humidity, such as bath-                          if anyone in your home is sensitive to these

                                                                                                                         MIKE CIESIELSKI
rooms, kitchens, laundry rooms, and base-                              allergens. Wash sheets, pillowcases, and blan-
ments are sources for these living pollutants.                         kets weekly. This removes dust mites’ primary
Mold can be found growing on paper, textiles,                          source of food—your dead skin cells.
grease, dirt, and even soap scum.                                                                                                          A barbeque grill is an example of a CO-producing
                                                                                                                                           device. Never use a grill indoors.
      Rather than a single substance, house                            Carbon monoxide
dust is a varied mixture of potentially aller-                   According to the Journal of the American
genic materials. It may contain fibers from            Medical Association, 1,500 Americans die                                            be released where it is needed: the brain,
different types of fabrics; cotton lint, feathers,     each year from accidental exposure to CO, and                                       heart, and skeletal muscle. For more informa-
and other padding materials; dander from               over 2,000 from intentional exposure (sui-                                          tion on this topic, see Tim Graham’s article
cats, dogs, and other animals; bacteria; food          cide). Carbon monoxide is an extremely haz-                                         “The Silent Killer” in the February 2005 issue
particles; bits of plants and insects; and other       ardous gas that has no warning taste or odor.                                       of ChemMatters.
allergens peculiar to an individual home.              It is produced by incomplete combustion of                                                Carbon monoxide buildup occurs when
      House dust also contains microscopic             organic fuels such as wood, gasoline, natural                                       flues or chimneys become blocked and
dust mites. Dust mites feed off of human dead          gas, coal, charcoal, and fuel oil. Like oxygen,                                     exhaust cannot be vented outside. Faulty fur-
skin cells. They live in bedding, upholstered          carbon monoxide binds to the iron atoms of                                          naces, fuel-burning space heaters, ovens,
                                                       the hemoglobin (Hb) protein molecules found                                         ranges, and even grills operated in the home
                                                       in our red blood cells, forming a complex                                           without adequate ventilation will also cause
                                                       called carboxyhemoglobin. Carbon monoxide                                           carbon monoxide buildup. To prevent this
                                                       binds to hemoglobin about 200 times more                                            exposure, carbon monoxide alarms and detec-
                                                     MIKE CIESIELSKI

                                                       strongly than does oxygen. It was long                                              tors are available in stores and should be
                                                       believed that because carboxyhemoglobin is                                          installed to alert you of dangerous levels. Also
                                                       unable to transport oxygen, fatal carbon                                            make sure you have your combustion heating
                                                       monoxide poisoning is due to asphyxiation.                                          systems and chimneys checked by trained
                                                       This sounds bad enough, but a detailed exam-                                        professionals every year.
                                                       ination of carbon monoxide poisoning reveals
                                                       a more complicated, more insidious situation.                                       Safe haven
Dude—do you have any idea what’s                               Hemoglobin is a tetramer, that is, each                                            Even though we have only listed several
crawling all over your pillow?                                      hemoglobin protein has the ability to                                  of the many toxic indoor air contaminants, the
                                                                      bind to four oxygen molecules. Its                                   subject can be frightening. Our homes should
furniture, and carpets;                                                 oxygen binding exhibits a phe-                                     be a safe haven, not a hazardous waste dump.
thriving in summer and                                                   nomenon called cooperativity:                                     Every time you get dizzy, have a sore throat,
then dying off in winter.                                                once the first oxygen molecule                                    or have itching, burning eyes will you wonder
The Mayo Clinic estimates                                                binds, the protein changes its                                    if it has to do with the air quality of the room?
the average bed contains                                                shape in such a way that the                                       Education is the key to keeping your indoor air
between 100,000 and 10                                                 remaining three sites bind oxygen                                   clean and healthy. Remember, it’s not just the
million dust mites. You may                                          more tightly. This is physiologically
                                                                 V                                                                         outside air we have to be concerned with any-
be sharing your bed with mil-                       .ARS
                                                                  important, making Hb better at binding
                                                 WWW                                                                                       more. A little forethought and action can go a
lions of them! The particles seen                      O2 in the oxygen-rich lungs and better at                                           long way in preventing major health problems
floating about in a shaft of sunlight include          releasing O2 in the oxygen-poor muscles.                                            arising from contamination occurring in your
dead dust mites and their waste products.              However, the CO-bonded iron looks (as far as                                        own home.
Dust mites have been identified as the single          the protein is concerned) a lot like the O2-
most important trigger for asthma attacks.             bonded iron. So the Hb shifts into high-affinity
Asthma, a chronic ailment that afflicts millions       mode when even one CO is bound per protein
around the world, causes inflammation of the           molecule. This means that it picks up the O2
airways and affects the way air enters and             well in the lungs but cannot release it in the
leaves the lungs, thereby disrupting breathing.        tissues! A person suffering from exposure to
      You can pinpoint these triggers of indoor                                                                                            Michelle Laliberte is a science writer living in
                                                       carbon monoxide actually has high oxygen                                            Medina, OH. This is her first article for
allergens in your home by visual detection.            blood content. It’s just that the oxygen cannot                                     ChemMatters.

14 ChemMatters, OCTOBER 2006                                 

                                               The New Alchemy                              By Michael McClure

      n 1927, Georges Lemaitre, a        duce, so these elements will not                 Before we dive into these dis-
      Belgian priest, proposed that      form under the conditions of a nor-         coveries, let’s first take a look at the
      the universe began with a cos-     mal star. But the enormous energy           basics of radioactivity.
      mic explosion of gigantic pro-     available in an exploding supernova
      portion. He suggested that         is sufficient to drive nuclei and other     Radioactivity
      before the explosion, there was    particles together. As nuclei are                 Radioactivity refers to sponta-
a time when all of the matter and        forced to absorb protons and neu-           neous nuclear reactions that occur
energy of the universe were packed       trons, they can grow to form ele-           in various forms. Atoms that decay
together into one fantastically dense    ments with masses greater than that         by alpha emission, for example,
and unstable mass that he called         of iron, and they can continue to           eject a particle consisting of 2 pro-
the cosmic egg. A few minutes after      grow, forming elements as heavy as          tons and 2 neutrons, in other words,
the violent blast, protons and neu-      uranium.                                    a helium 2+ ion. The decay product,
trons joined to create simple atomic                                                 or daughter, is an element with two
nuclei. Some time later, electrons       The early years:                            fewer atomic number units. For
began interacting with the nuclei        Who were the                                example, the isotope uranium-238
and atoms of the simplest ele-                                                       decays into thorium-234 by alpha
ments, hydrogen and helium, were         players?                                    emission.
formed. As the rapidly expanding                Billions of years later after that
universe cooled, great clumps of         initial, tremendous blast, scientists           238
                                                                                         92 U   ➞ 234 Th + 4 He
                                                                                                   90      2
gas condensed, heated up, and            in the 19th and 20th centuries
exploded in a burst of light. The        would organize all of the known ele-
first stars were born.                   ments into neat rows and columns                  Other modes of radioactive
       The stars were the crucibles in   based on properties and atomic              decay include beta decay, positron
which nuclei were fused to form          composition—the Periodic Table. In          emission, and electron capture.
heavier elements. A star’s energy        those early years, discoveries came               Radioactivity can be used as a
comes from the fusion of nuclei as       fast and furious. It was predicted          tool for exploring the atomic
mass is converted to energy,             that new discoveries might one day          nucleus. In 1919, the New Zealand-
according to Einstein’s famous           reveal elements with masses and             born physicist Ernest Rutherford
equation E = mc2. Carbon, oxygen,        atomic numbers beyond uranium.              observed the reaction between alpha
neon, and all of the elements up to      What were these discoveries? Who            particles and gaseous nitrogen
and including iron are synthesized       were the men and women that                 atoms in a cloud chamber. The cloud
during the life cycle of a star. Ele-    unlocked the secrets of atoms and           chamber is a flask filled with super-
ments beyond iron are made when          created the first transuranium (i.e.,       saturated vapor, in this case, nitro-
massive stars end their lives as         “beyond uranium”) elements? Who             gen gas. Alpha particles streaking
supernovae. The nuclear reactions        succeeded in doing what early               through the vapor knocked electrons
that produce elements beyond iron        alchemists failed at—transforming           from nitrogen molecules, creating
                                                                                                                                GETTY IMAGES

require more energy than they pro-       one element into another?                   electrically charged ions. Vapor mol-

                                                                                                                ChemMatters, OCTOBER 2006 15
ecules condensed around the ions, allowing                                                                slow neutrons. Other research groups were
Rutherford to see the alpha particle path as a                                                            performing similar experiments. Initially,
trail of tiny droplets, like the contrails of a jet                                                       everyone claimed success in creating a new
aircraft.                                                 Transmutation is                                element with atomic number 93. But the mass
       Rutherford recorded the short tracks of                                                            of the product did not agree with the expected
many alpha particles in his experiment. Occa-            the transformation                               mass of element 93. Furthermore, its chemi-
sionally, he observed condensation tracks                                                                 cal properties seemed surprisingly like bar-
that were longer than expected. Because                  of one element into                              ium, an element much lighter than uranium.
longer tracks implied less massive particles,                                                             Lise Meitner, an Austrian physicist, was trou-
Rutherford suggested that perhaps alpha                    another through                                bled by these findings. Looking closely at the
particles were knocking out protons from the                                                              results and making detailed calculations she
nucleus of nitrogen atoms. Gaining two pro-               one or a series of                              came to the astonishing conclusion that
tons, then losing one proton would change                                                                 uranium nuclei were splitting into smaller
the nitrogen nucleus into oxygen-17. Ruther-              nuclear reactions                               fragments! In seeking new elements beyond
ford had just observed the first artificial trans-                                                        uranium, Fermi and others had stumbled upon
mutation of an element.                                                                                   the process of atomic fission. This discovery
                                                                                                          and the subsequent development of nuclear
      7N     + 2 He ➞
               4           17
                                  + 1H                Building new atoms                                  weapons and nuclear reactors impacted all of
                                                      and a stunning                                            Today, we know that Fermi’s uranium
     Transmutation is the transformation of           discovery                                           sample contained trace amounts of uranium-
one element into another through one or a                   Early alchemists worked furiously trying      235, a rare isotope that undergoes atomic fis-
series of nuclear reactions                           to change one element into another, and they        sion when bombarded with neutrons. What
                                                      all came to the same conclusion: it’s not easy.     Fermi and others did not realize was that ele-
An artificial isotope                                 What they did not know is that positively           ment 93 had actually formed in the experiment,
      Later on in 1934, Irene Curie-Joliot, the       charged protons inside the nucleus of every         but was undetectable in the complex mixture.
daughter of Marie and Pierre Curie, and her           atom repel similarly
husband Fredrick Joliot performed an experi-          charged particles. The
ment similar to Rutherfords’. Instead of nitro-       characters of our story
gen, they used aluminum as the target. In             found that only posi-
addition to protons flying away from the colli-       tively charged particles
sion event, they observed the emission of             with sufficient energy
neutrons and some new form of radiation               can overcome the
(called a positron emission). Surprisingly,           strong repulsive forces
when they stopped the experiment, neutron             and penetrate the
emission stopped, but the radiation contin-           nucleus. For this rea-
ued. How could this be? Curie-Joliot and her          son, Enrico Fermi, an
husband discovered that the reaction created          Italian physicist, sug-
the artificial element phosphorus-30. This            gested that neutrons
isotope does not occur in nature, and it              might make better

                                                                                                                                                             ACS STAFF
decayed into silicon by this newly discovered         nuclear missiles. Neu-
form of radiation—positron emission. They             trons carry no electri- The process of nuclear fission.
had witnessed the first artificial transmutation      cal charge; they are
of a stable element into a radioactive isotope,       neutral. Fermi and others believed that if a
by emission of an artificial form of radiation.       nucleus captured a neutron, it would try to          A planetary element
In 1935, the Curie-Joliot’s shared a Nobel            correct for its neutron excess by beta decay,              The emission of alpha particles creates a
Prize for this work.                                  turning a neutron into a proton, thus creating       recoil effect. This causes the product isotopes
                                                      an atom with an atomic number increased by           to fly away from each other and deposit some
                                                      one unit. Suppose uranium, the heaviest              distance from where the decay event
                                                      known naturally occurring element, could be          occurred. American physicist Edwin McMillan
      13Al   + 4 He ➞
                           15 P
                                  + 0n                forced to capture a neutron. This might make         in the Radiation Laboratory at the University
                                                      the uranium nucleus unstable and radioactive.        of California, Berkeley, wanted to know exactly
                                                      If the unstable nucleus decayed by beta emis-        how far the fission products would travel
             15P   ➞   30
                       14 Si
                               + +1e                  sion, a new element beyond uranium would             through matter. His experiment was simple.
                                                      be created.                                          First, he stacked thin sheets of paper together
                                                            Fermi and his collaborators bombarded          to form a small book. On the top sheet he
                                                      uranium-238 (atomic number 92) atoms with            placed a sample of uranium salt. Next, he

16 ChemMatters, OCTOBER 2006                
exposed the salt to a source of neutrons,                 of uranium-239 and neptunium were formed.
which induced fission. As expected, the fis-              And the long half-life of the unknown isotope
sion fragments traveled through the paper                 made it difficult to measure its activity.
sheets stopping at various layers in the book.            Seaborg’s group knew they would need to
McMillan could determine the location of each             synthesize larger quantities of neptunium if
fission product by separating the pages and               they were to be successful in identifying the
measuring the radioactivity with a Geiger                 mysterious product. They solved these prob-
counter. But in addition to finding various fis-          lems with the help of (American physicist)
sion products scattered among the pages,                  Ernest Lawrence’s proton merry-go-round—
McMillan detected two separate beta activities            the cyclotron. Lawrence’s cyclotron could
in the topmost sheet. Two isotopes were not               accelerate particles to enormous speeds,
recoiling with the other fission fragments.               imparting enough energy to overcome the
      McMillan reasoned that perhaps not all              repulsive forces inside an atomic nucleus.

isotopes of uranium undergo fission. Maybe                Using the cyclotron, they produced large                       Seven-kilometer–long accelerator in French and
uranium-238 was indeed capturing a neutron,               quantities of neptunium and then watched as                    Swiss country side near Geneva.
as Fermi had suspected, and decaying into a               the neptunium decayed into an element with
new element. In 1940, Philip Abelson, another             atomic number 94. Seaborg’s group was able                     properties similar to the transition metals. In
American physicist from the Carnegie Institu-             to show that element 94 was radioactive,                       1944, Seaborg proposed his Actinide hypoth-
tion in Washington, went to Berkeley to help              emitting alpha particles with a half-life of                   esis. He predicted that thorium, protactinium,
McMillan identify the mysterious beta activi-             90 years. After the tradition of naming ele-                   uranium, and the first 11 transuranium ele-
ties. Soon they had successfully separated                ments for the planets, element 94 was named                    ments would form a series of chemically
and identified the first transuranium element.            plutonium.                                                     similar elements following actinium (atomic
They named the element neptunium (Np).                         McMillan moved on to other projects, but                  number 89), similar to how the lanthanides
                                                                                                                         follow lanthanum. Much research into the
                 + 0n ➞
                   1         239                                                                                         chemical properties of the transuranium ele-
          92 U               92 U
                                                                                                                         ments has confirmed Seaborg’s hypothesis.
          92 U   ➞   239
                     93 Np
                             + +1e                                                                                       The search
                                                                                                                         continues …
      Why name #93 neptunium? First take a
                                                                                                                               Today, 111 elements are listed in the
guess, and then look to the end of the article
                                                                                                          GETTY IMAGES

                                                                                                                         Periodic Table. There are 19 transuranium ele-
for the answer.
                                                                                                                         ments named after planets, countries of dis-
                                                                                                                         covery, and scientists. And elements beyond
The search went on …                                                                                                     atomic number 111 have been reported but
                                                          between 1944 and 1974, Seaborg’s group dis-
      McMillan suggested that the second                                                                                 remain unconfirmed and unnamed. Will there
                                                          covered nine additional transuranium ele-
short-lived beta decay product in the mixture                                                                            be an end to the discovery of transuranium
                                                          ments. A few were synthesized in ever larger
might be an element with atomic number 94.                                                                               elements? Will scientists reach the hypothe-
                                                          and more powerful cyclotrons, and some in
The American scientists Glenn Seaborg,                                                                                   sized “Island of Stability” where theory pre-
                                                          nuclear reactors. Two new elements, ein-
Arthur Wahl, and Joseph Kennedy were                                                                                     dicts elements with atomic numbers as high
                                                          steinium and fermium, were discovered in the
working on the World                                                                                                     as 126 may be stable? No one knows the
                                                          nuclear fallout during thermonuclear weapons
War II Manhattan Pro-                                                                                                    answers. But we do know the search will con-
                                                          testing in the 1950s.
ject with McMillan and                                                                                                   tinue, and perhaps you might be involved.
decided to test his                                       Revamping the                                                  Larger accelerators will be built to smash
idea. First, they had to                                                                                                 atoms. New detectors will allow researchers
overcome two difficult                                    periodic table                                                 to track and interpret the zoo of particles that
problems. In McMil-                                             Where did the transuranium elements fit                  form when atoms collide. And each new dis-
lan’s experiment,                                         into the Periodic Table? Scientists soon                       covery will increase our understanding of the

only small amounts       Glenn Seaborg                    learned that many transuranium elements had                    world around us, including you and me!

                                                                                                                         Mike McClure worked for several years as a
                                                                                                                         chemist at a veterinary diagnostic laboratory, inves-
                                                                                                                         tigating unusual animal deaths. He now teaches
                                                                                                                         chemistry at Hopkinsville Community College in
                                                                                                                         Kentucky and is a regular contributor to
                                                                                                                         ChemMatters magazine.

                                                                                                                                ChemMatters, OCTOBER 2006 17
Material Safety Data Sheets:

                                                          By Michael Tinnesand

           you’ve been out of high school for a few years and are enjoy-   control should be called at once. For substance #2, the fire-fighting
So,        ing your first job at a manufacturing plant. As manager in
charge of production, you have many job functions, not the
                                                                           instruction states, “Use triclass dry chemical fire extinguisher. Fire-
                                                                           fighters should “wear personal protective equipment (PPE) and self-
least of which is dealing with safety. Employees have                      contained breathing apparatus (SCBA) with full face piece, operated in
ordered some new supplies, and one of your tasks is                        positive pressure mode.” The MSDS advises for substance #3, that
to review the Material Safety Data Sheets (MSDS) for                           one should avoid contact with eyes, skin, and clothing. Wear chem-
each of the products. As you review the sheets look-                                ical splash goggles, chemical-resistant gloves, and chemical-
ing for hazards, you notice some alarming informa-                                      resistant aprons.
tion. For substance #1, the section on first-aid                                                Pretty scary. And what are these scary substances?
     measures advises if it is taken internally,                                                   Substance #1 is baking soda.
              large quantities of water should                                                      Substance #2 is beeswax.
                       be given and a physi-                                                        Substance #3 is cotton.
                                 cian or poison                                                     Scary indeed.
                                                                                                    Most students will recog-
                                                                                               nize baking soda as a common
                                                                                                                                                      ACS STAFF

                                                                                           kitchen ingredient, used for making
                                                                                         cookies and cakes. Far from being
                                                                                        considered a poison, it is often used as medicine for upset
                                                                                       stomachs when taken as “bicarbonate of soda”. Baking soda
                                                                                      is the common name for sodium bicarbonate (NaHCO3),
                                                                                     which is a weak base. Because it is a base, it can be used to
                                                                                    neutralize excess acid in your stomach.

                                                                                 NaHCO3 (s) + HCI (aq) ➞ NaCl (aq) + H2O (I) + CO2 (g)

                                                                                     18 ChemMatters, OCTOBER 2006
       Beeswax is a natural substance pro-                               But in order for an MSDS to be helpful,                                   So, how is it that so many MSDSs are
duced by honeybees. A mixture of long-chain                         they must be accurate. That means being                                 inaccurate or inappropriate? The primary
hydrocarbons and esters, there is no simple                         consistent and reasonable in stating the                                reason is that there is no one to check the
chemical formula, but the molecules making                          hazards associated with the materials in                                quality of MSDS content. After passing the
up this type of wax will typically have between                     question.                                                               legislation creating the MSDS, OSHA
20 and 40 carbon atoms. Beeswax is used in                               A recent article by Stephen Ritter in                              promptly excused itself from enforcing any
making wood polish and candles. The con-                            Chemical & Engineering News highlighted                                 level of quality in the sheets, instead leaving
ventional method of extinguishing the flame                         some of the issues. The article cites an exam-                          it to the manufacturers themselves to assess
of a beeswax candle is with a slight puff of                        ple of a MSDS for deionized water, hardly                               the hazards and write high-quality MSDSs.
air, usually from someone’s mouth. Cotton is                        hazardous by most standards, but a common                               As Chemical Safety for Teachers and Their
one of the oldest and                                                                                                                       Supervisors puts it, “Generally speaking,
most widely used textile                                                                                                                    MSDSs from well-known, established sup-
fibers in human history.                                                                                                                    pliers of laboratory chemicals are likely to be
It is used for all kinds of                                                                                                                 better and more reliable than MSDSs from
clothing, notably for                                                                                                                       other sources. Often, a comparison of
underwear, where it is                                                                                                                      MSDSs for the same chemical from a variety

worn next to the skin,                                                                                                                      of suppliers will suggest a source of MSDSs
generally without                                                                                                                           that is likely to be the most authoritative.”
resorting to goggles or aprons.                                                                                                                    OSHA recently responded to these con-
       What exactly are these Material Safety                                                                                               cerns with a study of the Hazard Communica-
Data Sheets and why do they seem intent on                                                                                                  tion Standards. The report, Hazard
scaring us out of using substances we know                                                                                                  Communication in the 21st Century Work-
to be safe?                                                                                                                                 place was published in March 2004. It makes
       MSDSs are a very important part of                                                                                                   a number of recommendations, including a
safety precautions mandated by the Federal                                                                                                  new short course to train those who write the
government some 25 years ago. Before that                                                                                                   MSDSs and a checklist to help review the
time, workers were on their own to discover                                                                                                 content of the MSDS.
the potential hazards of chemicals used in the                                                                                                     Perhaps, most importantly, OSHA staff
workplace. To make matters worse, many of                                                                                                   will begin to critically review the MSDS for 10
                                                                                                                          MIKE CIESIELSKI

the products they were using were listed only                                                                                               chemicals, working with manufacturers to
by their brand or trade names, often without a                                                                                              make certain they are accurate and reasonable.
list of ingredients.                                                When working with chemicals, be aware of the                                   So, perhaps things will get better. In the
                                                                    hazards involved. Know where the MSDSs are
This made it nearly                                                 kept and how to interpret them.                                         meantime, consult your teacher if you have
impossible to find                                                                                                                                                            any concerns
out what the hazards might be. In 1986, the                                                                                                                                   about chemi-
Occupational Safety & Health Administration                         item for use in research and academic labs.                                                               cals in the lab.
(OSHA) established the Hazard Communica-                            Information on the MSDS included the solubil-                                                             And you might
tion Standard. The standard requires that                           ity of water in water, a recommendation to                                                                want to be
    • Chemical manufacturers and importers                          wear gloves when dealing with it, and storing                                                             mindful of your
      must evaluate the hazards of the chemi-                       it in a cool, dry place! When getting deionized                                                           outdoor activi-
      cals they produce or import, and prepare                      water in the eyes, one sheet recommended                                                                  ties, especially
      labels and MSDSs to convey the hazard                         “irrigate with water”.                                                                                    when it comes
      information to their customers.                                      To be fair, it is important to note that the                                                       to dealing with
    • All employers with hazardous chemicals                        vast majority of MSDSs are probably accurate                                                              sand. If you
      in their workplaces must have labels and                      and helpful, but users are well advised not to                                                            follow the
      MSDSs for their exposed workers and                           rely on them without cross-checking.                                    advice from one MSDS and avoid making
      train them to handle the chemicals safely.                           The American Chemical Society Commit-                            contact with your skin or clothing, it is going
       Although the Hazard Communication                            tee on Chemical Safety publishes Chemical                               to put a real damper on your time at the
Standard does not apply to state and local                          Safety for Teachers and Their Supervisors,                              beach!
government, most states have enacted similar                        Grades 7–12. It notes, “Usually, MSDSs are
legislation or have endorsed the OSHA stan-                         not written for the laypersons: they require
dards. Therefore, public and private schools                        interpretation by persons familiar with the
must pay attention to MSDSs as well. As a                           technical terms used. Often, an overemphasis
result, many high school chemistry teachers                         is placed on the toxic characteristics of the                           Michael Tinnesand is the Associate Director of
receive instruction on how to read a MSDS as                        subject chemical. There may also be vague or                            Academic Programs at ACS. His most recent arti-
                                                                                                                                            cle, “The Dog Ate My Homework and Other Gut-
part of their general safety training for work in                   insufficient information regarding other haz-                           Wrenching Tales”, appeared in the April 2006 issue
the laboratory.                                                     ards that the subject chemical presents.”                               of ChemMatters.

                                                                                                                                                   ChemMatters, OCTOBER 2006 19
                                                  National Chemistry Week 2006
                                                          Poster Contest
                                        “ Your Home—It’s All Built on Chemistry ”

                                       As part of the National Chemistry Week 2006 celebration and in
                                       recognition of its theme, "Your Home—It’s All Built on Chemistry", the
                                       American Chemical Society (ACS) is sponsoring a poster contest for
                                       high school students.

                                       Students are invited to create a poster that will serve as a public service
                                       announcement emphasizing the role of science/chemistry in the home.

                                                             1st Place: $200 Gift Certificate to
                                                             2nd Place: $100 Gift Certificate to
                                                             There are also prizes for other categories (K-8),
                                                                and for the teachers of winning students.

                                       For important information about the contest, go to, or
                                       contact the American Chemical Society, Office of Community Activities
                                       at 800-227-5558, ext. 6097 or e-mail

                                                         National Chemistry Week October 22–28, 2006

1155 Sixteenth Street, NW
Washington, DC 20036-4800

Reach Us on the Web at

A publication of the Education Division of the American Chemical Society
         OCTOBER 2006

 It’s All Built
on Chemistry
   Also Inside:
Chemistry Builds
 a Green Home

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