Conductive pencils
Objective: Performing the electrolysis of water using pencils as electrodes
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Laboratory materials
Beaker
Conducting wires with crocodile clips
9V battery
2 Pencils
Cardboard
Tablespoon
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Reagents
Water
Sea salt
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Questions
What happens when the cables are connected to the battery?
Which reaction takes place?
Why is salt added?
Procedure
- Sharpen the two sides of the pencils and attach the wires to them using the crocodile clips.
- Fill the beaker with tap water and dissolve a tablespoon of see salt.
- Make two holes in the cardboard through which the pencils will pass (the ends where there are no wires).
- Place the cardboard with the pencils over the beaker and connect the free ends of the cables to the battery terminals.
- Observe what happens.
Theoretical explanation
Water (H2O) is a substance that can be decomposed into its elements, hydrogen and oxygen, through a chemical process. When electricity passes through water, both gases are produced, and that’s why we observe bubbles inside the beaker. This phenomenon is called electrolysis of water.
2 H2O 2 H2 + O2
Due to the low degree of ionization of water, its electrical conductivity is low. Salt is therefore added to increase the conductivity and allow the electrolysis of water to occur.
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