IB Chemistry
Brakke
ECA
Physical and Chemical Changes
Lab Activity
Introduction
Chemistry is the study of matter and the changes it undergoes. These changes can be broken down
into two classes: physical and chemical changes. In a physical change, one or more physical properties of a
substance are altered. Grinding, melting, dissolving and evaporating are all physical changes. No new
substance or substances are formed as a result of a physical change.
A chemical change results in the formation of one or more new substances. These new substances
differ in chemical properties and composition from the original substance. Rusting and burning are two
examples of chemical change.
Procedure:
For each part below, complete the procedure taking observations before and after and record them in
your lab notebook. Determine whether a chemical or a physical change has taken place, and whether the
reaction was exothermic or endothermic. Make sure to clean up all of your equipment and put everything back
where you got it. The procedures may be down in any order as long as all are done. Put previous materials
away before starting a new one. EACH PROCEDURE IS A DIFFERENT ACTIVITY.
1.
Place a scoop (using a scoopula) of ammonium chloride into a clean test tube. Into another clean test
tube place a scoop of (using a scoopula) of calcium chloride. Add 3 mL of water to each and mix.
Do not place finger over test tube and shake to mix. Use a stirring rod or tap with your finger. Also
never stopper and shake (unless instructed otherwise by the instructor).
Feel the outside of the test tube for any temperature changes. Are there any similarities between
them.
2.
Take a piece of pre-cut magnesium ribbon, and ignite it by holding it in the hottest part of the Bunsen
burner flame. Note its properties (color, luster, flexibility) before and after burning.
CAUTION:
3.
Take another piece of pre-cut magnesium and place it into a clean test tube. Place this test tube into a
test tube rack. Add about 2 mL of hydrochloric acid to this test tube. While one person in the group is
measuring out the acid, the other should ready a burning splint to insert into the top of the test tube.
Be thorough in your observations (rate of reaction, any temperature change, etc). Can you name the
gas that is evolved?
Caution:
4.
Do not look directly at the magnesium while it is burning.
Hydrochloric acid can cause severe burns. HANDLE WITH CARE. If you spill some on
yourself or the lab station put baking soda on it.
Into a clean test tube add 2 mL of sodium hydroxide solution. Place this test tube into a test tube
holder. Add 2 mL of copper (II) sulfate solution to the same test tube. Describe what happens.
Let set for 10-15 minutes, and again observe.
CAUTION:
Do not put these chemicals down the drain. Place them waste in fume hood.
IB Chemistry
5.
Brakke
ECA
Put one scoop (using a scoopula) of sodium bicarbonate (sodium hydrogen carbonate) into a clean dry
test tube. Place this test tube into a test tube holder also. Add 2-3 mL of acetic acid to this.
After about 10 seconds, place a burning splint into the top of the test tube (not into the liquid).
Describe your observations.
6.
Obtain a small piece of copper. Note its appearance and luster. Heat the copper in the Bunsen burner
flame for about 30 seconds. Use crucible tongs to hold the copper in the flame. Record your
observations.
7.
Fill the rounded bottom of a clean dry test tube with copper (II) sulfate pentahydrate.
Heat slowly and gently over a Bunsen burner. Hold the test tube in place using a utility clamp. Record
observations before and after heating
Let the test tube cool, and then add several drops of water to the cooled test tube. Record your
observations.
CAUTION:
8.
Do not put these chemicals down the drain. Place them in the waste container
in the fume hood.
Mix 2.0 grams of iron fillings with 2.0 grams of sulfur in a mortar and pestle. Place on a sheet or
partial sheet of white paper, and place a magnet underneath the paper. Record your observations.
Dispose of the iron fillings and sulfur in the receptacle on the demonstration table in the front of the
room.
9.
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