Experiment 3 - Chemical and Physical Properties by cuiliqing

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									Experiment 3 – Chemical and Physical Properties                    Name __________________
                                                              Lab Section __________________

         Experiment 3 – Chemical and Physical Properties of Materials
Introduction

Matter, the “stuff” that makes up everything we see, can be classified in several manners. It can
be found as a pure substance, an element or compound, or a mixture. Each of these will, in turn,
have both physical and chemical properties. To investigate these properties of matter, a few
definitions must be made.

Pure substances can either be elements or compounds. Elements are anything found on the
periodic table. As long as the matter is comprised only of that element, it is a pure substance. A
chunk of copper, oxygen gas, a lead weight, and a diamond (pure carbon) are prime examples of
a pure substance that is in an elemental form. A compound is also a pure substance made up of
more than one element, as long as there are no impurities. Pure water, sodium chloride, calcium
carbonate, and aluminum oxide, are examples of a pure substance in the form of a compound.

Mixtures occur when two or more elements or compounds are mixed together. There are two
types of mixtures, homogeneous and heterogeneous. Homogeneous mixtures are when the
properties of the solution are the same throughout. Examples of this would be salt water, air,
vanilla ice cream, and metal alloys like stainless steel. Heterogeneous mixtures are when the
properties can change, depending on where you are looking in the solution. Examples of this
would be and oil/water mixture, rocky road ice cream, and raw metal ores (metal mixed in with
dirt and such).

Each of these classifications of matter has both chemical and physical properties. A physical
property is one that can be observed without altering the substance. That is to say, it remains
unchanged after the observation. Examples of this include, but are not limited to, color, phase
changes (boiling, melting, and freezing points), solubility, miscibility, hardness, and density.
Each of these is observable without creating a new substance.

A chemical property is essentially whether or not the substance will react with another
substance. For instance, iron reacting with oxygen to form rust, and the fact that argon does not
react with anything, are both chemical properties. Chemical properties are observed in a
chemical reaction and a new substance is formed.

A physical property is determined when a physical change takes place. A physical change is
one in which the substance undergoes a change, but its composition remains the same. Examples
of this are a temporary color change (as in the heating of metal), breaking something in half to
determine its strength, or dissolving a substance in water.

A chemical change is observed in a chemical reaction. There are four ways to know if a
chemical change has occurred. These evidences are: permanent color change, gas being
released, formation of a solid (precipitate, abbreviated as PPT), and heat released/absorbed.
Examples of these would be iron rusting, antacid tablets fizzing in water, a solution turning a
milky color when mixed, and a solution heating up when mixed.
Experiment 3 – Chemical and Physical Properties                   Name __________________
                                                             Lab Section __________________

Prodecure

Physical properties – Observations of Elements

   Using the given samples of elements, describe their physical characteristics, determine their
   symbol, and indicate whether or not they are a metal, semi metal, or nonmetal.

Physical properties – Solubility of a Solid in Water – Soluble or Insoluble

    Half fill two small test tubes with water. Add a few crystals of copper (II) sulfate, CuSO4,
    into one test tube, and a small chunk of calcium carbonate, CaCO3 to the other. Gently
    shake the test tubes and note whether or not the solids dissolve. Note whether or not the
    solids are soluble or insoluble.

Physical properties – Solubility of a Liquid in a Liquid – Miscible or Immiscible

Add 20-30 drops, ~1 mL, of water into two test tubes. Add 20-30 drops of ethanol to one test
tube and 20-30 drops of hexane to the other. Note whether or not the solutions mix, and indicate
whether they are miscible or immiscible.

Chemical properties – Reactions of Elements (Instructor Demo)

   Observe a copper wire before and after being heated with a Bunsen burner. Indicate whether
   the wire underwent a chemical or physical change.

   Observe iodine crystals before and after being heated. Indicate whether the iodine underwent
   a chemical or physical change.

Chemical properties – Reactions of Compounds

   Add 20 drops of sodium carbonate, Na2CO3, and 20 drops of sodium sulfate, Na2SO4, into
   separate, small test tubes. Add hydrochloric acid, HCl, to each the test tube and note any
   changes that might occur. Indicate if the addition of hydrochloric acid resulted in a chemical
   or physical change.

   Add 20 drops of calcium nitrate, Ca(NO3)2, and 20 drops of copper (II) nitrate, Cu(NO3)2,
   into separate, small test tubes. Add 20 drops of ammonium hydroxide, NH4OH, to each test
   tube and note any changes that might occur. Indicate if the addition of ammonium hydroxide
   resulted in a chemical or physical change.
Experiment 3 – Chemical and Physical Properties                   Name __________________
                                                             Lab Section __________________

Boiling Point Measurement

Boiling Point – Methanol

   Refer to Figure 3.1 for the setup of the boiling point apparatus. Fill a 400 mL beaker ¾ full
   with water, add a boiling chip to the beaker, and support it on a ring stand with an iron ring
   and wire gauze. Add between 1-2 mL of methanol into a large test tube and put a boiling
   chip into the methanol. Place a thermometer into a split rubber stopper and suspend the end
   of the thermometer approximately 1 cm above the methanol. Use a test tube clamp to hold
   the test tube to the ring stand. Bring the water to a boil using the Bunsen burner and shut off
   the burner. Lower the methanol into the beaker. The alcohol will begin to boil and liquid
   will begin dripping from the bottom of the thermometer. When this is observed, read the
   thermometer. When the temperature no longer continues to rise, record the temperature. Be
   careful not to allow the methanol to completely boil off.

       Safety Note: Methanol is very flammable! It is imperative that the Bunsen burner be
       shut off before the methanol is introduced to the beaker to avoid possible vapor ignition.
       Keep all flames far away from the methanol!


Boiling Point – Unknown Liquid

Obtain an unknown liquid from your instructor and record its number. Repeat the instructions
above using your unknown liquid.

Figure 3.1
Experiment 3 – Chemical and Physical Properties                      Name __________________
                                                                Lab Section __________________

Prelaboratory Questions

What are the four ways you know a chemical reaction has taken place?



Give your own example of:

Homogeneous mixture


Heterogeneous mixture


Element


Compound


Physical Change


Chemical Change



Is each of the following a chemical or physical property:

Iron rusts            ____________                  Rust is red in color      ____________

Iron is malleable     ____________                  Iron’s density is 5.8     ____________


Is each of the following a chemical or physical change:

Gasoline burns in air ____________                  Ice melts                 ____________

Salt dissolves in water____________                 Milk sours                ____________
Experiment 3 – Chemical and Physical Properties                   Name __________________
                                                             Lab Section __________________

Data Table

Physical Properties – Observations of Elements

   Element           Symbol       Physical Characteristics    Metal/Semi/Nonmetal
    Oxygen
    Silicon
    Argon
  Magnesium
  Aluminum
     Iron
    Sulfur
 Phosphorous
   Mercury
    Cobalt
      Tin
    Sodium
    Arsenic




Physical Properties – Solubility of a Solid in Water

                                       Observation            Soluble or Insoluble?

Copper sulfate in water             ________________          ___________________

Calcium carbonate in water          ________________          ___________________


Physical Properties – Miscibility of a Liquid in Water

                                       Observation            Miscible or Immiscible?

Ethyl alcohol in water              ________________          ___________________

Hexane in water                     ________________          ___________________
Experiment 3 – Chemical and Physical Properties               Name __________________
                                                         Lab Section __________________

Chemical Properties – Reactions of Elements (Instructor Demo)

                                           Observation                Physical or
                                                                    Chemical Change

Copper wire and heat                   ____________________         _______________

Iodine and heat                        ____________________         _______________


Chemical Properties – Reactions of Compounds

Potassium hydrogen carbonate
And heat                               ____________________         ________________

Ammonium hydrogen carbonate
And heat                               ____________________         ________________


Chemical Properties – Reactions of Solutions

Sodium carbonate and
Hydrochloric acid                      ____________________         ________________

Sodium sulfate and
Hydrochloric acid                      ____________________         ________________

Calcium nitrate and
Ammonium hydroxide                     ____________________         ________________

Copper (II) nitrate and
Ammonium hydroxide                     ____________________         ________________



Boiling Point Measurement

Boiling Point – Methanol                  ________ °C


Boiling Point – Unknown #_______          ________ °C
Experiment 3 – Chemical and Physical Properties                   Name __________________
                                                             Lab Section __________________

Postlaboratory Questions


1) Indicate whether the following properties are representative of a metal, semi metal, or
nonmetal:

Left hand side of the Periodic Table                                            _____________

Brittle                                                                         _____________

Can behave like a metal or nonmetal                                             _____________

Malleable                                                                       _____________

High melting point                                                              _____________

Reacts with nonmetals                                                           _____________

Reacts with metals and nonmetals                                                _____________



2) Classify each of the following as an element, compound, homogeneous mixture, or
heterogeneous mixture.

Mercury metal, Hg                      __________   mercury (II) chloride, HgCl2 __________

Amalgum fillings (silver in mercury) __________     mercury in sand                __________



3) Indicate whether each of the following is a chemical or physical property:


Color of the material                  __________   Hardness                       __________

Boiling point                          __________   Reacts with oxygen             __________


4) Indicate whether each of the following is a chemical or physical change:

Tomato ripens                          __________   Frying an egg                  __________

Water boils when heated                __________   Chopping wood in half          __________

								
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