Name:__________________________ Date: ________________________________
Types of Changes
Purpose:
To classify the changes which occur to substances as either physical or chemical.
Hypothesis:
It is predicted that the following experiments will be chemical changes: #___________________.
It is predicted that the following experiments will be physical changes: #___________________.
Materials:
___ test tubes
retort stand
matches
magnesium ribbon
marble chips
___ watch glasses
calcium carbonate
hydrochloric acid
beaker with hot water
test tube rack
sugar crystals
iron filings
magnet
sealed test tube with iodine
tweezers
sodium hydroxide solution
calcium chloride solution
Alka Seltzer
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Procedure:
A. Sugar and Iron Mixture:
1. With a spatula, place a small quantity of sugar in a watch glass.
2. Using a magnet under the watch glass, note any magnetic properties.
3. With a spatula, place a small quantity of iron filings in another watch glass.
4. Using a magnet under the watch glass, note any magnetic properties.
5. Combine contents of both watch glasses together in one of the watch glasses.
6. Bring the magnet close to the mixture under the watch glass.
7. Record and compare the properties of the substances before and after mixing.
B. Burning Magnesium: (DO NOT STARE AT THE FLAME)
1. Take a piece of magnesium ribbon and record its properties in the table.
2. Grasp the ribbon between tongs and ignite it with the bunsen burner.
3. Record the properties of the magnesium after burning.
C. Mixing Calcium Carbonate (marble chips) and Hydrochloric Acid (HCl)
1. Record the properties of a marble chip and a sample of HCl.
2. Place a piece of marble chip into a test tube and add a few drops of HCl.
3. Record the properties after mixing the two subtances.
D. Mixing Calcium Chloride and Sodium Hydroxide solutions
1. Record the properties of the calcium chloride and sodium hydroxide solutions.
2. Place a few drops of the calcium chloride solution into a test tube and add a few drops of the sodium
hydroxide solution.
3. Record the properties after mixing the two subtances.
E. Heating Iodine:
1. Obtain a sample of iodine in a sealed tube and record its properties.
2. Dip the sealed tube into a beaker of warm water for a few seconds.
3. Record the properties after heating.
4. Compare the properties before and after the change.
5. Dip the warmed tube back into cold water. Observe the change.
Observations:
Properties before
Sugar
Iron filings
Magnesium
Marble chip
HCl
Change
Properties after
Combine
Burn
Dissolve
Calcium
Chloride
Sodium
hydroxide
Iodine
Mix
Heat
Follow-Up: 1. Which of the experiments above were chemical changes?
Experiments number _____________________________ were chemical changes.
2. Which of the experiments above were physical changes?
Experiments number _____________________________ were physical changes.
3. Indicate if the change is chemical or physical.
Chemical
a)
iron rusting

b)
glass breaking

c)
paint fading

d)
gluing wood

e)
leaves turning yellow

f)
dynamite exploding

g)
eggs frying

h)
water boiling

i)
sugar dissolving in water

j)
silver tarnishing

Physical










Neither










4. What conditions are needed to identify a chemical change? (List 4)
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