Docstoc

FORTUNE TELLER FISH

Document Sample
FORTUNE TELLER FISH Powered By Docstoc
					 CHEMISTRY
DEMOS, LABS,
AND PROJECTS
             GSTA 2010




                  Nancy Brim
              Lakeside High School
            Nancy_H_Brim@fc.deKalb.k12.ga.us
  http://fc.dekalb.k12.ga.us/~Nancy_H_Brim/GSTA2010
Name ___________________________________________ Period _____ Date____________________



                                              FIRST DAY STATIONS

Station A     Syllabus - Pick up the two pages of the syllabus. Read through it, sign it, and answer the following
              questions. Be sure to get your parents to sign it tonight.
              1. How many points do you lose for late work EACH day?
              2. List three things you should have everyday for class.
              3. How much is the project that coincides with the periodic table worth?
              4. Do we study the orbital configuration of neutral atoms this semester?
                      If so, what standard is it?

Station B     Textbook - Select a text book and a textbook form. Fill out the form using the laminated example. Put
              your name AND my name in your textbook on the inside cover. Answer the following questions. Bring the
              form and textbook to your teacher.
              1. How much does it cost to replace your textbook?
              2. What chapter is about the Mole?
              3. Define DENSITY and give the page number where you found it.
              4. Who was Dmitri Mendeleev and give the page number where you found it.

Station C     Safety Contract - Pick up the two different safety contract sheets – one is double sided, the other is not.
              Read through the both sheets. Ask questions on any you do not understand. We will go over this in more
              detail later this week. Read through the signature sheet. Fill it out using the example as a guide. Be sure to
              enter the due date. Sign it, and answer the following questions. Be sure to get your parents to sign it by the
              due date.
              1. How do you correctly light a Bunsen burner?
              2. What does a glass beaker look like when it is hot?
              3. How do you correctly smell a chemical?
              4. What are the penalties for unsafe conduct in the lab?

Station D     Pick up a Student Information Record. Please fill out the top portion, through “Tell me about yourself and
              your family”. Flip over to the back and fill out the “Interest Inventory”. Any information that you do NOT
              know should be filled in tonight at home and returned to me tomorrow.

Station E     Write down the following quote from Henri Poincaré. This is your homework and it is due tomorrow. In at
              least two paragraphs (and at least ten sentences), write a response to it. I do not want to know Webster’s or
              Google’s definition of science, I want to know what YOU think.
                       “Science is built of facts that way a house is built of bricks; but an accumulation of facts is no
                       more science than a pile of bricks is a house.”
                                                                           - Henri Poincaré


Station F     Find the seating chart for your period and fill in your name in the appropriate seat box. Be sure to fill in
              named called and last name. Also, put your called name and last name on a popsicle stick on place the stick
              in the BRIM can.

Station G     We‟ve Got the Blues lab
                                                 WE’VE GOT THE BLUES
        A method by which a scientist solves a problem is called the scientific method. This method usually includes observation,
experimentation, hypothesis formation, and interpretation. The scientific method is no more than a means in which people solve
problems (it is very similar to the method a detective uses to solve a crime!).

Purpose:           This investigation creates a problem for you and asks you to solve it. In the investigation you will:
                   a.) make careful observations; b.)record accurate data; and c.) use your data (recorded results) as a basis for
                   deciding if two given liquids are similar or different.

Materials:         two test tubes containing liquid               50 mL beaker                goggles
                   clock or watch with a second hand              250mL beaker

Procedure:
Part A: Observation
    1. Examine the two test tubes. Do not remove the stoppers and do not shake the contents.
    2. Notice the test tubes have been labeled A and B. Record in Data Table One 2 -3 similarities or differences between the two
         test tubes.
    3. Answer the questions below the data table.

Data Table One – Initial Observations
               Similarities                                                Differences




1.   Do you think both test tubes contain the same liquid?             YES                    NO
2.   Is your answer to question one based on experimentation or guessing?

3. Are both test tubes exactly alike in the amounts of liquids?            YES                NO

4.   What gas may be in the upper half of test tube A that is not in test tube B?



5.   Is there any direct evidence for your answer to question 4?           YES                NO

Part B: Experimentation
    1. Give each test tube one hard shake using an up and down motion with your hand. Put your thumb over the stopper when you
         shake.
    2. Record your observations in Data Table Two and answer the questions.

Data Table Two – One Shake Observations
               Similarities                                                Differences




6.   After shaking the test tubes, do you think they contain different liquids?     YES          NO

7.   Is it possible that the liquids in both test tubes are the same and that the space above the liquid is responsible for any change that
     occurred?                                                     YES           NO
                                            DENSITY COLUMN
                                             EXTRA CREDIT
        You are to construct a density column using an approximately 500 mL plastic (no glass) soda bottle or
some other type of plastic container. You must have a minimum of FIVE layers, with extra, extra credit being
given for additional layers. Each layer must be neatly labeled on the bottle itself next to each layer. Your name
and period should also be on the bottle.
        This project will involve a great deal of experimentation where you will need to mix different substances
to see which ones will not dissolve in one another, and which will float on top of one another. It is a good idea
to use food coloring to make some of the layers more visible.

Some Safety Precautions:
   1. Do not use ammonia, bleach, or anything that contains ammonia or bleach. Toxic fumes may be
      produced.
   2. Always read the labels of all substances you try and follow necessary safety precautions.
   3. Do not use any flammable substances (like lighter fluid, gasoline, paint thinner) as many of these react
      with plastics.
   4. Try to stick with things you drink or cook with. Try to avoid cleaning substances (see #1).
   5. If you mix two things in your bottle and they begin reacting, as evidenced by fumes being given off or
      bubbles being produced, DO NOT PUT THE CAP BACK ON! Take it outside immediately until the
      reaction ceases.

    Prizes will be awarded for the bottle with the most layers that are clearly visible and for the most colorful
bottles. Good Luck!



                                              DENSITY DEMO
Materials:     fish tank, water, variety of canned drinks

I start out with Coke, Diet Coke, and Caffeine Free Coke. Have a discussion about which the students think
     will sink and which will float.
Put cans in water (be sure to put them in sideways so that air will not catch in the bottom of the can). Coke will
     sink, Diet Coke will float, Caffeine Free Coke floats.
Challenge your students to bring in other drinks – Sprite, Coke Zero, etc.
If the cans are left in overnight, they all float - brings up an interesting discussion.
                                           GLOW IN THE DARK STARS
Materials:       package of glowing stars, laser pointer, flashlight, UV light, three books/magazines

1. Place a glowing star in each of three books/magazines the day before you use them so there is no stored light.
2. Give one student the laser pointer, one the flashlight, and one the UV light.
3. Give necessary safety precautions about the lights.
4. Turn the lights off and have the students hold their light source on the stars for 30 seconds.
5. At the end of 30 seconds, turn off the light and close the book.
6. Next, have the students check to see if their stars are glowing.
DATA
   1. laser light - 670 nm wavelength                  stars glow? ____________________________
   2. flashlight - 500 nm wavelength                   stars glow? ____________________________
   3. ultraviolet light - 254 nm wavelength            stars glow? ____________________________
   4. glowing star light - 520 nm wavelength
CALCULATIONS
   A. Convert wavelength in nm to meters.
        Example:          Convert wavelength in nm to meters.
        Laser: (670nm) (1.00 x 10-9m/1 nm) = 6.70 x 10-7m

  B. Using Planck‟s energy formula and the speed of light formula, determine the energy for each.
     Calculating Frequency υ = c ÷ λ
     Laser: υ = c † λ = (3.00 x 108m/s) ÷ (6.70 x 10-7m) = 4.48 X 1014 Hz
     Calculating Energy                   E=hυ
     Laser: E = h υ = (6.626 x 10-34 Js)(4.48 X 1014 Hz) = 2.97 x 10-19J
CONCLUSION
  1. Would infrared light cause the stars to phosphoresce?
  2. Would microwave light cause the star to phosphoresce?
  3. Give another example of minimum energy photons.




                                                       NATURE OF LIGHT

Materials:       three LED lights (red, green, blue)          Write and See Square


    1.   Move the red light on the yellow vinyl square and look for a trail of green glowing pigment.
    2.   Move the green light on the yellow vinyl square and look for a trail of green glowing pigment.
    3.   Move the blue light on the yellow vinyl square and look for a trail of green glowing pigment.

         Blue will leave a trail because it has enough energy to excite the phosphorescent pigment. The excited pigment then slowly
    releases the energy as green light. Red and green light to not have enough energy to affect the pigment. Therefore, the Write and
    See Square has a minimum energy requirement that is not met by red or green light. (Write and See Square and LED lights from
    www.teachersource.com)
         Our eyes have a minimum energy requirement of approximately 750 nm or 4.00 x 10 -11Hz (red light).




                                       NUT and BOLT STOICHIOMETRY
    1.   Give each group a bag of nuts, bolts, and washers.
    2.   Show them a set (one nut, one bolt, and one washer)
    3.   Have them put together as many sets as they can.
    4.   One the board, record the nuts, bolts, washers, and sets for each group.
    5.   Discuss limiting reactant, excess reactant.
                                                                                           Teacher Notes

                      Activity – Electron Configuration Battleship
Summary
Students practice electron configuration – standard notations – using the “Battleship” game format. Students may play
one-on-one or in teams of two. Students claim this activity is both fun and a very effective method of practicing electron
configuration. Time frame: 30 minutes or more.

Chemistry Concepts: electron configuration – standard notations (and noble gas if option is played)

Materials
Game rules overhead transparency                         periodic tables – laminated and in folders
Vis-à-vis markers

Procedure Notes
The general format of the game “Battleship” involves placing ships on a grid hidden from the opponent‟s view. The
opponent “fires” at your ships by naming grid coordinates (e.g. B3). You respond by stating whether the shot was a “hit”
or a “miss.” Likewise, you fire at your opponent‟s ships. All shots are recorded by placing pegs in the game board (red
for a “hit,” white for a “miss”). A ship is “sunk” when all available spots on the ship have been hit. Whoever sinks all of
his opponent‟s ships first is the winner.

The primary modification in this game is the firing method. Instead of naming grid coordinates, students must give the
electron configuration of the targeted element. To make sure both students are in agreement, the opponent confirms the
targeted element by saying its name. If both students agree, the electron configuration was most likely stated correctly.
Students are only allowed to use aids that will be available on tests.

Individual vs. Team Play: This game is most appropriate for individual play. However, if a student was absent when
the material was presented, pairing him with a knowledgeable student is an ideal way for him to catch on.

Periodic Tables: These are laminated and stapled to folders. Each person gets one folder. Unfold the folders “laptop”
style and attach back to back with a paperclip so they stand up.

Markers: Vis-à-vis markers are used since the periodic tables are laminated.

Another Option:

Material addition: poker chips, dice, etc. (to provide a random selection between 2 choices)

Poker chips/Dice: These are used by the students to randomly select between the standard notation or noble gas notation
so that both methods can be practiced. Any number of alternatives could be used instead of poker chips. Additional
Directions:

Player #1 draws a chip and “fires” at an element by giving the appropriate electron configuration.
              red chip – standard notation
              blue chip – noble gas notation
             Electron Configuration Battleship
Materials (per group of two)
  2 laminated periodic table folders
  2 different colored markers
Game Rules
    1. Each player uses a marker to draw one ship per sublevel. Each ship should be arranged
       vertically or horizontally and should occupy the specified number of boxes.
              s-sublevel – Destroyer –
              p-sublevel – Cruiser –
              d-sublevel – Battleship –
    2. Players now switch colored markers
    3. Player #1 “fires” at an element by giving the appropriate electron configuration (not the
        shorthand one).
    4. Player #2 confirms the targeted element by saying its name and declares it a “hit” or “miss.”
    5. Player #1 records the “hit” with an “X” or “miss” with an “O” using colored marker.
    6. Players trade roles.
    7. The player who sinks all of his or her opponent’s ships first is the winner!

                                                                                                  Transparency Directions



                                         DEMO OF THREE BOND TYPES
Materials:        two plastic/tennis balls (need to be hollow balls)    thin rope

Have two students come up to the front of the class. Have them face each other. Each student holds a ball, representing an electron.
The other end of the rope is held by the other student. Each student should be holding a ball in one hand and the other end of the rope
is attached to his partner‟s ball in the other hand.

IONIC: One student wear a piece of paper that reads Cl EN = 3.0. The other wears one that says Na EN = 0.9. Ask the class to
predict the positions of the electrons. The electron belonging to Na should be transferred almost completely to the Cl atom. The Cl
should move a little towards the Na. This shows that no bond is 100% ionic.
POLAR COVALENT: use CO. Two cards are C EN = 2.5 and O EN = 3.5. The electrons are closer to the o than the C, but
approaching the center of the two atoms. This shows unequal sharing.
NONPOLAR COVALENT: Use H2. Two cards are H EN = 2.1. The electrons therefore will be in the exact center of the ropes
since each is equally attracted to the other‟s nucleus.




                                                  PLAYING BINGO
Students are told to pull out one of their nomenclature worksheets. They are to put the written name or formula
in each of the bingo boxes. I have a particular handout that I use and I have cut the names/formulas into strips.
I have cut up a bunch of pieces of colored paper as markers. They can use any resource that they can use on the
test (periodic table and/or ion names). The students cover the flask with a marker. When I call out a
name/formula, it is the answer to the written one the students wrote down. Students must learn to hear a
formula and find the name and vice versa. We play until someone gets five in a row and then keep playing (no
one clears their card) until we run out of time.
BINGO
Name _____________________________ Period _____ Date __________________


                                            A Roll of the Die
Purpose: To practice writing names and formulas of compounds

Materials:      Bag of ion die             paper             writing utensil

Procedure:      1. Open the bag of dice and separate the anions from the cations.
                2. Picking up one anion die and one cation die, roll them on a hard surface.
                3. In the table below, write the ions as they appear, then write the formula and the name of the compound.
                4. Repeat steps 2 and 3 with the same two dice four more times. If you get the same set of ions again, re-roll.
                5. Put those two dice aside and pick up another anion die and another cation die. Roll them on a hard surface,
                   write their ions, formula, and name. Do this four more times with those dice.
                6. Put those two dice aside and pick up another anion die and another cation die. Roll them on a hard surface,
                   write their ions, formula, and name. Do this four more times with those dice.
                7. Pick up a remaining anion die and the cation die with Cu +2 on it. Roll them on a hard surface; write their ions,
                   formula, and name. Do this four more times with those dice.
                8. Pick up the last anion die and the cation die with Al +3 on it. Roll them on a hard surface; write their ions,
                   formula, and name. Do this four more times with those dice.

Data

  CATION           ANION              FORMULA                                           NAME
                                            OFF TO THE RACES


Introduction: If a little is good, more is better right? Increasing the mass of a reactant in a chemical reaction
       may not increase the amount of product that can be formed – the yield may be limited based on the mole
       ratio of the reactants. You will see for yourself the concept of limiting and excess reactants by
       comparing the amount of carbon dioxide obtained when varying amounts of sodium bicarbonate react
       with a constant amount of acetic acid.

Safety: Acetic acid is a skin and eye irritant. Avoid contact with eyes and skin. Wear goggles.

Materials:      2M Acetic acid            NaHCO3 (solid)            6 balloons
                6 125mL Erlenmeyer flasks funnel                    scoopula
                10mL graduated cylinder   weigh boats               electronic balance

Procedure:
      1. The teacher will assign you a flask and a number, 1-6.
      2. To your flask add 10.0mL 2M acetic acid.
      3. Measure out the assigned amount of NaHCO3 into your weigh boat using the electronic balance. See
           Table One for all amounts.

                                                 TABLE ONE

                                    SAMPLE                     Mass NaHCO3
                                       1                           0.50g
                                       2                           1.00g
                                       3                           1.50g
                                       4                           2.00g
                                       5                           2.50g
                                       6                           3.00g

       4. Obtain a balloon for your flask. Stretch the balloon and blow it up at least once. Then let as much
          air out of it as possible.
       5. Use the funnel to add your sample of NaHCO3 to the balloon.
       6. Carefully attach the balloon over the mouth of the flask. Don‟t let any NaHCO3 into the acetic acid
          yet.
       7. Make a prediction as to what will happen when the NaHCO3 is added to the acetic acid in all six
          flasks. How will the size of the inflated balloons vary when the reactions are complete? (Write your
          answer below IN INK!)

           Largest: __________________________________________________:Smallest
       8. When your teacher says so, all students will lift their balloons and shake them so that the NaHCO3
           falls into the acetic acid. Make sure the neck of the balloon stays firmly attached to the flask.
       9. The reaction is immediate and vigorous. Allow the reaction to proceed until all the bubbling stops.
       10. Compare the size of the inflated balloons and whether the solid is all gone in each case. Rank the
           balloons below:

             Largest: __________________________________________________:Smallest
Calculations:
        Your goal is to calculate the theoretical number of moles of gas produced in EACH reaction. You have
two reactants to work with - Sample grams #1-6 NaHCO3 and 10.0 mL HC2H3O2. You will then identify the
limiting reactant and the excess reactant in each case. The balanced equation is:

                      NaHCO3 (s) + HC2H3O2 (aq)  NaC2H3O2 (aq) + CO2 (g) + H2O (l)

   1. Calculate the number of moles of CO2 produced for each mass sample of NaHCO3. Be sure to show all
      work, units, and significant figures. Put a box around your answer for each sample calculated. Put this
      on a separate piece of paper please.
   2. Calculate the number of moles of acetic acid used. Then calculate the theoretical mass of CO2
      produced. Your teacher will do this with you. Put this on a separate piece of paper please.
   3. Once you have the answers to #1 and #2, fill in the table below:

   Sample       Moles of CO2     Moles of CO2     Moles of CO2        Limiting       Excess
                produced by      produced by      theoretically       Reagent        Reagent
                  NaHCO3          HC2H3O2           produced




   4. Discuss what you learned about this reaction using the calculations above and your knowledge of
      limiting reactants.
   5. How did the relative sizes of the balloons compare to your answers of theoretically produced CO2?
                                            THE BIG CHILL
                                       INSULATION PROJECT

Problem:       Which substances offer the best insulation from heat transfer by conduction, convection, or
radiation?


Materials:     fiberglass insulation, wood, Styrofoam, cardboard, etc. (Just suggestions, you are the final
               decision-maker on the structure.)

               1. Design and build a container for a “pet” ice cube.
               2. The container cannot be bigger than 15cm on any side.
               3. The container must have an opening to accommodate an ice
                  cube – see photo.
               4. All containers must be original creations. (In other words,
                  Tupperware and Thermos products, or any other
                  manufactured products are not allowed.)
               5. The final project must operate at room temperature without electricity.
               6. We will not work on this in class at all.
               7. Once you give the project to me on the due date, you may not touch it again until you get your
                  grade for it days later.

    Grading:   You may work by yourself or in a team of two (you and one other person). Each member of the team
    must participate fully in the project. There will be no free rides. Don’t choose someone who is not going to
    work! The container will be graded as follows:

               Construction – built neatly by hand (25 pts), completed on time (10pts), all sides no more than 15cm
                 long (5 pts each side)
               Efficiency – based on life span of ice cube. < 2hr (25pts), 2-3.5 hr (35 pts), 3.5-4.5 hrs (40 pts),
                 4.5-5.0 hrs (45 pts), >5 hrs (50 pts)
               There will be bonus points for being one of the top three finishers in your class, for ice cubes
                 lasting longer then 8 hrs, for best design, and for parent signature on form.



DUE DATE:                                     Competition Date:


Members of group: ____________________________                ________________________________
(print)                               you                                your partner, if any

Materials Used in Project:




Parent Signature ______________________________________ Date ____________________
                                  This signature adds five points to your grade!!
Names _____________________________________ Period _____ Date _________________________

         ____________________________________


                                        PLAYING WITH BALLOONS AND CANS

          We are beginning the section on the Gas Laws. These are laws that deal with how pressure, temperature and volume are
interrelated when used with gases.

         For each of the activities, do the following. I am looking for a thoughtful analysis of each situation, using the gas laws as a
basis around which to form your intelligent well-reasoned responses.

         1.   Record all observations in paragraph form. Please make detailed observations, above and beyond what is specifically
                      asked for.
         2.   For the conclusion for each experiment, explain why you observed what you did. If you can determine a relationship
              between temperature and pressure, temperature and volume, or volume and pressure, say what that relationship is. If a
              gas law applies, give the name of the law and how it applies. Do not just state the definition of the law, but rather state
              how this law specifically applies to each situation.


          You will turn in one lab for each lab group. This sheet should be on top with the answers in chronological order attached.
No title page is required. Each member in the group should initial which responses they answered.



WEAR GOGGLES FOR THESE
1. Too Hot to Touch: Pour about 25 mL of water into a soda can. Fill the white bucket half full of water and add one cup of ice.
   Place can on a ring stand with an iron ring and wire gauze and heat to boiling. After steam has been rising out of the can for
   several minutes, firmly grasp the can with the beaker tongs. Quickly invert the can (open end down) and submerge into the
   bucket of ice water. Make observations of what happened while heating and once the can is placed in the bucket.

2.   An Utterly Deflating Event: Place about 10mL of very hot water (get from the back desk) in a large test tube and attach a
     balloon to the test tube. Heat the water to boiling (don‟t melt the balloon!). Make observations. Quickly plunge the test tube into
     a beaker of ice water. Make observations.


YOU CAN TAKE YOUR GOGGLES OFF IF THE PEOPLE ACROSS FROM YOU ARE ALSO FINISHED WITH #1 AND
#2.
3. Up, Up, and Away: Blow up a balloon all the way. Feel the surface of the balloon and note the temperature of the balloon.
    Make observations. Deflate the balloon and note its temperature. Make observations.

4.   Can You Pull Enough? Fill a clean cup with water. Take a sip of water with the straw. Make observations. Using scissors, cut
     out a small piece of the straw above the water surface. Then drink out of the straw again and make observations.

5.   From a Stream to a Trickle: Fill a two liter bottle with water, keeping a finger over the hole at the base. Inflate a balloon and
     attach to the top of the bottle. Remove your finger from the hole holding the bottle over the sink. Make observations. Remove
     the balloon. Fill the bottle again with water, attach a deflated balloon, and remove your finger from the hole while holding the
     bottle over the sink. Make observations.
                             THREE PHASES OF MATTER DEMOS

Molecular Motion:
        Materials: 3 tennis balls, clear tennis ball can, gallon size Ziploc bag
SOLID: Put the balls in the can with the lid on and shake the can. This shows molecules/atoms moving/vibrating
around a fixed point, unable to break away.
LIQUID: Pour the tennis balls into the Ziploc bag and close it. Move the bag around showing that the
molecules/atoms touch each, have more freedom of movement, but do not break apart.
GAS: Get a student to juggle the three balls. Even if he/she drops the balls, they stay in the “container”
(classroom).

Compressibility:
        Materials: 3 syringe with end caps, Georgia red clay, water, air
SOLID: Put 4cm3 of Georgia red clay into syringe and cap.
LIQUID: Put 5mL of water into syringe and cap.
GAS: Put 7 mL of air into syringe and cap.
Give each to a student. Ask the student to notice the starting volume and then push on the plunger as hard at they
can. Determine the new volume.



                                    GIANT TUBES OF SCIENCE

Buy the long 8 foot covers for fluorescent light bulbs. Cap one end and fill so it seals. I used heavy duty
glue and duct tape.

You can run several demos with this:
   1. Fill the tube ¾ full with 0.1M NaOH and universal. Place in a bucket to help with overflow. Add
       several pieces of dry ice and watch the colors change.
   2. Fill tube ¾ full with 0.1M HCl and enough Universal to get the red color. Add 1.0M Na2CO3
       gradually to the tube. Color variations of the rainbow should appear. Na2CO3 sinks, neutralizes
       the HCl. At various depths, the [H+]varies, producing layers of varying pH.


                                      INSTANT CARNATIONS

Buy three or four silk flowers. Soak each one in a different indicator. Squirt them with ammonia water
to show the base color. Over time, they will return to their original color as the ammonia evaporates. I
used phenolphthalein and universal indicators.




                                            FINDING ACIDS

Soak a light colored sponge in Congo Red indicator. The sponge will turn red. As students are doing a lab
with acids, walk by and wipe the sponge across any spill on the counter. Acid spills will turn the sponge a
dark blue/black. This drives home the need to clean up all spills immediately.
                                     QUALITATIVE ANALYSIS
                                    OF HOUSEHOLD CHEMICALS


        Years ago, the American Chemical Society offered a prize to anyone who could find a substance that
was not a chemical. The point, of course, was that all matter, whether “artificial” or “natural,” is composed of
atoms and molecules. Although most students readily accept this truism, they often view the chemicals they
work with in the laboratory as something different from the materials that abound in the “real world.” This
experiment, in which the „active ingredient” in many household products will be identified, is an attempt to
bridge the gap between the chemistry lab and the household environment.
        You will be provided with a number of white solids, identified only by an alphabetical code. Your job
will be to identify each of these unknowns correctly. The possibilities are table salt, sugar, Epsom salt, alum,
photographic fixer, corn starch, aquarium sand, chalk, baking soda, and washing soda. Many of these materials
are likely to be found in the typical home. Others, while not as common, are readily available in pharmacies,
building supply stores, or camera shops, and may be purchased without a special license or prescription.
        Suggestions for identifying the unknowns using chemical tests are made below. Note that many of the
test reagents are themselves in products commonly used in the home. For instance, anthocyanin is an extract
from red cabbage. It acts as an acid-base indicator in the pH range of 3-10. Acetic acid (HC2H3O2) is a weak
acid, with a characteristic sour taste; vinegar is essentially a 1 M solution of acetic acid. Ammonia is usually in
a gaseous form; its aqueous solutions are alkaline and are commonly used as household cleaners. Pure iodine is
a solid that sublimes at slightly elevated temperatures. Alcoholic solutions of iodine (tinctures of iodine) are
often used as disinfectants.
        The information given below should enable you to devise a plan for identifying the unknowns. The
formulas given are those of the main ingredient in each household item (of course, the materials used in the
home are generally not pure and there is no single formula for the complete mixture.)

Solubility in Water
       Chalk, (main ingredient: CaCO3, calcium carbonate), cornstarch (main ingredient: a polymer of glucose
(C6H10O5), and aquarium sand (main ingredient: SiO2, silicon dioxide) are insoluble in water. Epsom salt (main
ingredient: MgSO4  7H2O, magnesium sulfate heptahydrate) dissolves with a noticeable cooling effect.

Reaction with Ammonia
        Addition of aqueous ammonia to a solution of Epsom salt produces “milk of magnesia”, a suspension of
magnesium hydroxide that has a milky appearance.
        Alum (main ingredient: NH4Al(SO4)2  5H2O, ammonium aluminum sulfate pentahydrate) is used as an
astringent and as a pickling agent. Addition of aqueous ammonia to a solution of alum produces a gelatinous
precipitate of aluminum hydroxide. The other water-soluble unknowns do not react with ammonia.

Reaction with Acetic Acid
       Like all carbonates, chalk will fizz when treated when acid. Washing soda (main ingredient: Na2CO3,
sodium carbonate) and baking soda (main ingredient: NaHCO3, sodium hydrogen carbonate or sodium
bicarbonate) will fizz when treated with acetic acid.

Reaction with Iodine
       Photographic fixer (main ingredient: Na2S2O3 . 5H2O, sodium thiosulfate pentahydrate) is soluble in
water and is capable of reducing I2 molecules to I- ions. It will decolorize brown iodine solutions and also
remove the blue color of the iodine-starch complex. Starch will turn blue when treated with iodine.
Reaction with Anthocyanin
       Red cabbage juice is a natural indicator that works in a pH range of 3-10. Washing soda turns a
yellowish/green, baking soda turns blue, and table salt, sugar (sucrose, C12H22O11), photographic fixer, and
Epsom salts turn violet.


Conductivity of Electricity
       Table salt (main ingredient NaCl, sodium chloride), like Epsom salt, alum, fixer, washing soda, and
baking soda, produces ions when dissolved in water. Thus, solutions of table salt will conduct electricity.


PROCEDURE
        Devise a scheme for separating unknowns into groups and then identifying the members of each group.
You should base your procedure on the groups discussed before this. No matter where you start, you will find it
helpful to follow the suggestions given below.
        1. In determining solubility, use only a pea-sized (or smaller – like the size of an earring stud) quantity
            of solid placed in a test tube. Add roughly 10 mL of water and mix well. You need just enough
            solid to be easily seen if it does not dissolve but not enough to form a saturated solution if it is
            moderately soluble. A slight cloudiness may be due to a trace of insoluble filler and should not lead
            to a conclusion of “insoluble” if major portions of the sample dissolves.
        2. To determine if an unknown will fizz when treated with acid, place a pea-sized quantity of solid in a
            test tube and add a few drops of acetic acid.
        3. When testing materials with anthocyanin, ammonia, or iodine, dissolve the unknown in water and
            add only two or three drops of reagent.
        4. Remember that reagents may interfere with one another. For instance, if you have several solutions
            and add iodine to each, all of the solutions, except the one containing the photographic fixer, will
            turn brown. Adding anthocyanin (in an effort to determine pH) would then be futile; the brown
            color would mask any other colors that might develop. Use fresh samples whenever it seems
            necessary.
        5. To test for conductivity, use your 100mL beaker. Add a pea-sized amount of solid and 10-20mL of
            deionized water (no tap water). When using the conductivity tester, make sure that you have dipped
            the prongs in water and wiped them off. Be sure to clean the prongs between each test. ONLY THE
            PRONGS GET WET – NOTHING GREEN SHOULD GET WET!!!!!
        6. Do not add anything to the containers of unknowns or test reagents. Do not move spatulas from one
            container to another. DO NOT CONTAMINATE!!!!



Writing Your Lab Report

       When writing up this lab report, please include the following sections:
                                                    Title page
                                                Safety precautions
                                          Materials (all that you used)
                                Procedure (tests for each unknown performed)
                                            Data (observations noted)
                            Conclusion (state the name and formula of each unknown
                                          and reason why it is correct)
        For example, after writing the title page, start a new page with the safety precautions and materials. One
way to write the report would be to then have a section for each unknown. State the letter of the unknown
chemical, the tests performed and the observations noted. That is technically the procedure and data section
together. Then in your conclusion, list each unknown‟s letter, formula, and what chemical you determined it to
be, and reasons for your choice. When writing the tests performed, there is no need to write out the step by step
for the test unless it is one that was not listed for you above. Just say something like “Chemicals A-J were
tested for solubility in water”. I would like to know the order in which the tests were done.
        Or, you can write each procedure and tell on which compound(s) it was performed. Then have a data
section where you list your observations for each. Either way, make it easy to read and follow...
        This is an individual lab report and your conclusions should be based on your own scientific judgment,
not that of others. You will be working with your partner at your lab desk, but drawing your own conclusions.
As a result, you and your lab partner can draw different conclusions based on the same data.
        Follow all the instructions for writing regular lab reports - a copy is posted in the classroom if you have
forgotten. Remember to use only third person.
       This lab report is due on ____________________


                                 LEGIBILITY IS VERY IMPORTANT !!
                                          (If I cannot read it, I will not grade it!)
 ============================================================================================

                                    \HOUSEHOLD CHEMICALS LAB
                                              GRADING RUBRIC

Getting the Correct Answer - 25%
       9-10 correct             25 pts           5-6      correct             14 pts
       7-8  correct             19 pts           <5       correct             10 pts

Lab Report - 50%
   Title page - 5 pts if all parts are evident, 3 pts is information is missing, 0 pt if missing
   Safety - 5 pts if sufficient safety rules are listed, 3 pts for a partial list, 0 pts if section missing
   Materials - 5 pts if all materials are listed, 3 pts for a partial list, 0 pts if section missing
   Procedure - 10 pts for all procedures listed or explained, 5 pts for a partial list, 0 pts if missing
   Data, Observations, Analysis - 20 pts if all data, observations and analyses are listed and I follow your
   deductive reasoning; 13 pts if most of the data and analyses are there, 6 pts if most of the data and analyses
   are missing, 0 pts if missing entirely
   Conclusion - 10 pts for all chemicals identified with formula and reason , 7 pts for two of three parts, 4 pts
   for one of three parts, 0 pts if missing)
Classification - 25 %
   Performed tests - 15 pts if all tests were performed on all chemicals, 10 points if some tests were
   performed, 5 pts if very few tests were performed, and 0 pts if no tests were performed
   Presented Data - 10 pts if data is presented in an organized and logical way, 5 pts if the data is somewhat
   confusing, 0 pts if data makes no sense at all

				
DOCUMENT INFO
Shared By:
Categories:
Tags:
Stats:
views:73
posted:10/25/2011
language:English
pages:17