Name ________________________________
You must wear goggles for the entire lab even when you are just writing something down.
Reactions Lab – Part 2
DECOMPOSITION REACTIONS
Splint tests are used to detect if a gas is produced during a reaction. The following are three results that
can be obtained from performing a splint test:
Burning splint extinguishes: carbon dioxide (CO2) is a product of the reaction
Glowing splint relights:
oxygen (O2) is a product of the reaction
Burning splint held over the end of a test tube creates a popping sound:
hydrogen (H2) is a product of the reaction
Reaction 4 – calcium carbonate decomposes upon heating
Procedure:
1.
Place a small scoop of calcium carbonate into a test tube. If some residual powder is already
in the test tube from the last class, that is fine. Do not rinse with water.
2.
Using a test tube clamp positioned near the top of the test tube, hold the test tube over a
Bunsen burner for about 5 minutes. (Safety Precautions: Point the opening of the test tube
toward the wall, away from anyone. Do not put test tube clamp in flame.)
3.
Observe the products.
4.
Light a wooden splint and hold it into the test tube. Observe.
5.
Place the hot test tube in the metal test tube rack to cool.
6.
Clean up: After cooled, the burned splint and matches go in trash along with powder from
inside the test tube. Do not rinse test tube. If some powder is left, that is fine.
QUESTIONS
1. What did the reactants look like?
2. What did the products look like?
3. Why did the flame go out?
4. What specific type of reaction (EOC Reference tables) of decomposition is this?
5. What is the balanced chemical equation for this reaction?
Reaction 5 – hydrogen peroxide decomposes in presence of catalyst
Procedure:
1.
Pour approximately 10 mL of hydrogen peroxide into a small Erlenmeyer flask.
Name ________________________________
You must wear goggles for the entire lab even when you are just writing something down.
2.
3.
4.
5.
6.
Light a splint and let the splint burn for 10 seconds. (Safety Precaution: Do not burn the
splint near any other lab chemicals, including the hydrogen peroxide!)
Drop one small scoop of MnO2 into the peroxide.
Blow the splint out.
While the splint is glowing, lower it into the flask, but do not let it touch the liquid. Observe.
Clean up: Dispose of mixture in designated waste container in the hood. Use a small amount
of water to rinse more MnO2 into the waste container. Return to your lab table and finish
rinsing the flask in the sink. Dry flask. After cooled, the burned splint and matches go in the
trash.
QUESTIONS
6. What did the reactants look like?
7. What do the products look like?
8. Why did the glowing splint reignite?
9. In this reaction H2O2 decomposes into water and oxygen with MnO2 as a catalyst. What is the
balanced chemical equation for this reaction? Make sure to include the catalyst in the
appropriate location.
Reaction 6 – water decomposes with electricity
Procedure:
1. Fill petri dish half full, add 3-4 drops universal indicator and 3-4 drops sodium sulfate.
2. Connect carbide electrodes with alligator clips to the opposite sides of the petri dish
Questions:
1. Write the reaction.
2. Write your observations.
3. Why did one part of the water turn purple?
4. Why did the other side turn dark pink?
5. What were the bubbles at either side.
6. What specific type of reaction (EOC Reference tables) of decomposition is this?