Classifying Reactions Lab
Name __________________________
7th Grade PSI Science
Score
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Experiment Question:
What properties of substances are most helpful in determining if a physical change or a
chemical reaction has happened?
Hypothesis Starters:
1. What two properties discussed in class do you think will be most useful in helping
you determine if something that happens is a physical change? Explain your
thinking.
2. What two properties discussed in class do you think will be most useful in helping
you determine if something that happens is a chemical reaction? Explain your
thinking.
Purpose:
In this experiment, you will explore the changes that occur when substances are
exposed to things that will cause them to change. Many of these substances will change
in characteristic and predictable ways that will help you determine what has happened
to the substance being tested. Remember, a physical change is when you change a
property of the substance without changing what the substance actually is. A chemical
reaction is when you change the properties of the substance by changing it into a
different substance.
Materials and Directions:
The materials and directions for each station are included individually. Complete
each station your teacher has set up before moving on to the next station. There are
extra station spaces at the end for you to write in stations that you have created or that
your teacher has created for you to test in addition to the standard stations.
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Chemical Reactions and Energy
Station 1A: Ice Station
Materials:
Beaker filled with ice
Empty beaker
Thermometer
Source of heat (hot plate, hair dryer,
Bunsen burner)
Directions:
1. Observe the solid ice and take its temperature
2. Place one or two cubes of ice in the empty beaker.
3. Add heat until the ice changes.
4. Observe the changed ice and record its temperature if possible.
Temperature Before
Observations
Before:
Temperature After
Observations
After:
Station 1B: Liquid Water Station
Beaker filled with water
Empty beaker
Graduated cylinder, 10 mL
Thermometer
Source of heat (hot plate, hair dryer, Bunsen burner)
Directions:
1. Observe the liquid water and take its temperature
2. Place 5.0mL of liquid water in the empty beaker.
3. Add heat until the liquid water changes.
4. Observe the changed water and record its temperature if
possible.
Temperature Before
Observations
Before:
Materials:
Temperature After
Observations
After:
Materials:
Directions:
Station 2A: Match Station
Safety Matches
Ceramic dish
1. Observe the safety match when you take it out of the box.
2. Strike the match and place it in the ceramic dish to safely
observe it during the change.
3. Observe the match after the change.
Observations
Before:
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Chemical Reactions and Energy
Observations
During:
Observations
After:
Materials:
Directions:
Station 2B: Lit Candle Station
Safety Matches
Unlit Candle
1. Observe the unlit candle.
2. Use the match to light the candle.
3. Make observations of the candle for two minutes while it is lit.
4. Carefully blow out the candle.
5. Make observations of the candle for two minutes after the flame
is gone.
Observations
Before:
Observations
During:
Observations
After:
Materials:
Directions:
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Station 2C: Candle Wax Station
Safety Matches
Unlit Candle
Scrap Paper
Tongs or Hot Glove
1. Use the match to light the candle.
2. Wait until the wax around the flame has started to melt.
3. SAFELY observe the melted wax.
4. Carefully blow out the candle.
5. Using the tongs or hot glove, quickly and carefully pour some of
the melted wax onto the piece of scrap paper.
6. Make observations of the wax for two minutes after it was
7th Grade PSI
Chemical Reactions and Energy
poured onto the paper.
Observations
Before:
Observations
After:
Materials:
Directions:
Paper
1.
2.
3.
Station 3A: Scrap Paper Station
Scissors
Observe the original paper.
Use the scissors to cut the paper into smaller pieces.
Observe the smaller pieces.
Observations
Before:
Observations
After:
Materials:
Directions:
Station 3B: Lit Paper Station
Scrap Paper
Safety Matches
Unlit Candle
Tongs
Scissors
Ceramic Dish
Metric Ruler
1. Observe the original scrap paper.
2. Cut a 1.0cm by 1.0cm piece from the paper.
3. Use the match to light the candle.
4. Use the tongs to hold the 1.0cm by 1.0cm piece of paper over
the flame until it starts to burn.
5. Place the burning paper in the ceramic dish so you can safely
make observations during the change.
6. Make observations of the paper after the change stops.
Observations
Before:
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Chemical Reactions and Energy
Observations
During:
Observations
After:
Materials:
Directions:
Station 4A: Sugar and Water Station
Beaker
Sugar
Distilled or Deionized
Water
Graduated cylinder Spoon/Scoopula
Current tester
1. Observe the sugar and water individually.
2. Test each individually with the current tester if one is available.
3. Combine one spoonful (approximately 1 – 2 grams) of sugar into
100mL of water and stir for 2 minutes or until you can no longer
see any solid sugar.
4. Observe what happens during the stirring.
5. Observe the mixture after stirring is complete.
6. Test the mixture with the current tester if one is available.
Observations
Before:
Observations
During:
Observations
After:
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7th Grade PSI
Chemical Reactions and Energy
Materials:
Directions:
Station 4B: Salt and Water Station
Beaker
Salt
Distilled or Deionized
Water
Graduated cylinder, 100 mL
Spoon/Scoopula
Current tester
1. Observe the salt and water individually.
2. Test each individually with the current tester if one is available.
3. Combine one spoonful (approximately 1 – 2 grams) of salt into
100mL of water and stir for 2 minutes or until you can no longer
see any solid salt.
4. Observe what happens during the stirring.
5. Observe the mixture after stirring is complete.
6. Test the mixture with the current tester if one is available.
Observations
Before:
Observations
During:
Observations
After:
Materials:
Directions:
Station 4C: Sand and Water Station
Beaker
Sand
Distilled or Deionized
Water
Graduated cylinder, 100 mL
Spoon/Scoopula
Current tester
1. Observe the sand and water individually.
2. Test each individually with the current tester if one is available.
3. Combine one spoonful (approximately 1 – 2 grams) of sand into
100mL of water and stir for 2 minutes or until you can no longer
see any solid sand.
4. Observe what happens during the stirring.
5. Observe the mixture after stirring is complete.
6. Test the mixture with the current tester if one is available.
Observations
Before:
Observations
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During:
Observations
After:
Materials:
Directions:
Beaker
Station 5A: Two Solutions Station
Test Tube of Solution A- sodium tetraborate
Stirring Rod
Test Tube of Solution B – polyvinyl alcohol
1. Observe each solution individually.
2. Combine the contents of the two test tubes into the beaker and
stir with the stirring rod.
3. Observe what happens during the stirring.
4. Observe the mixture after stirring is complete.
Observations
Before:
Observations
During:
Observations
After:
Materials:
Directions:
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Station 5B: Two More Solutions Station
Beaker
Test Tube of Solution C- silver nitrate
Stirring Rod
Test Tube of Solution D – sodium chloride
1. Observe each solution individually.
2. Combine the contents of the two test tubes into the beaker and
stir with the stirring rod.
3. Observe what happens during the stirring.
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Chemical Reactions and Energy
4. Observe the mixture after stirring is complete.
Observations
Before:
Observations
During:
Observations
After:
Materials:
Directions:
Station 5C: One Solution and One Powder Station
Beaker
Powder- sodium bicarbonate
Stirring Rod
Test Tube of Solution E – acetic acid
1. Observe the solution and the powder individually.
2. Combine the solution and the powder in the beaker and stir if
necessary.
3. Observe what happens during the stirring.
4. Observe the mixture after stirring is complete.
Observations
Before:
Observations
During:
Observations
After:
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Custom Station
Materials:
Directions:
Observations
Before:
Observations
During:
Observations
After:
Custom Station
Materials:
Directions:
Observations
Before:
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Chemical Reactions and Energy
Observations
During:
Observations
After:
Laboratory Questions:
On a sheet of paper or in your laboratory notebook, answer the following questions for
each station you were able to test.
1. What do you think was the most important change of property for the station?
Explain your thinking.
2. Based on that change, do you think the change was a physical change or a
chemical reaction? Explain your thinking.
3. Is the change reversible? Explain your thinking.
Conclusion:
On a sheet of paper or in your laboratory notebook, write one or two paragraphs that
summarize the experiment results and cover the following key points.
1.
2.
3.
4.
5.
What stations had physical changes and what stations had chemical reactions?
What changes were common for physical changes?
What changes were common for chemical reactions?
What changes were common for both physical changes and chemical reactions?
Is it possible to determine whether a physical change or a chemical reaction has
happened by observing the changes that happen to the substance or substances
involved?
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Chemical Reactions and Energy