Electrolysis of Water
Name: ____________________________
Date: ____________________________
Period: ______
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Materials:
1 beaker
2 paper clips
2 alligator clip leads
1 note card
200 mL of water
1 9V hobby battery
4 teaspoons of table salt
Before you start:
1. What do you think will happen when you hook up the battery to the metal electrodes (paper clips)
that are in the water?
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2. Procedure
1. Unbend two paper clips and make a hook shape, as shown in the diagram above.
2. Punch two holes (about 3cm apart) in your index card and label the holes + and -.
Hook the paper clips through until the hook part just touches the card.
3. Put about 200 mL of water into the beaker
4. Place the index card on top of the beaker. If the straightened ends of the paper clips are not
at least half covered, add more water.
5. Attach a wire to one pole of the battery. Attach a second wire to the second pole.
6. Using the + and – notations on your notecard, attach the wires from the battery to the correct
paper clips. Do not allow the paper clips to touch each other.
7. Allow your setup to run for 2 minutes. Record your observations on the back of this page.
8. After two minutes are up, please disconnect your battery.
3. Observations
What do you see while the system is running?
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4. Add 4 teaspoons of salt to your beaker and stir until dissolved. Reattach your battery and
run for an additional 2 minutes. Record your observations below.
What do you see while the system is running?
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Disconnect your battery after 2 minutes.
5. Analyze and Conclude
A.) Based on your observations of both systems, what substances do you think were produced at
each electrode?
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B.) Compare the properties of the substances produced to those of the original liquids.
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C.) Based on your observations, does electrolysis produce a chemical change? EXPLAIN your
reasoning.
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D.) Was there a difference in the rate of reaction between your salt water sample and your regular
tap water sample? If you saw a difference, what might account for it?
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E.) What do you think would happen at each electrode if you switched the wires on the battery
during the middle of the experiment? Why?
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