LESSON 5 ELECTROLYSIS (Experiment to show migration of ions during electrolysis)

One experiment that demonstrates the migration of ions during electrolysis is the electrolysis of water using a solution of sodium sulfate (Na2SO4). This experiment showcases the migration of both positively and negatively charged ions.

Materials:
1. 9-volt battery or a power source
2. Two graphite electrodes (pencil leads or graphite rods)
3. Sodium sulfate solution (Na2SO4)
4. Two wires with alligator clips
5. Beaker
6. Voltmeter (optional)

Procedure:
1. Fill a beaker with the sodium sulfate solution, ensuring that it covers the graphite electrodes completely.
2. Connect one graphite electrode to the positive terminal of the battery using a wire with an alligator clip.
3. Connect the other graphite electrode to the negative terminal of the battery using another wire with an alligator clip.
4. Immerse both graphite electrodes into the sodium sulfate solution, making sure that they do not touch each other.
5. Turn on the power source (battery) and allow the electrolysis process to occur for a few minutes.

Observations:
1. Bubbles start forming around both electrodes, indicating the release of gases.
- Oxygen gas (O2) will be produced at the positive electrode (anode).
- Hydrogen gas (H2) will be produced at the negative electrode (cathode).

Explanation:
During the electrolysis of water using the sodium sulfate solution, the following reactions occur at the electrodes:

At the anode (positive electrode):
2H2O(l) → O2(g) + 4H+(aq) + 4e-
Water molecules break down, producing oxygen gas, positively charged hydrogen ions (H+), and releasing electrons.

At the cathode (negative electrode):
4H+(aq) + 4e- → 2H2(g)
The positively charged hydrogen ions (H+) from the water are reduced, accepting electrons to form hydrogen gas (H2).

This experiment clearly demonstrates the migration of ions in the solution. The positively charged hydrogen ions (H+) migrate towards the cathode, where they are reduced to form hydrogen gas. Conversely, the negatively charged sulfate ions (SO4 2-) remain in the solution as sodium sulfate is a neutral salt.

By observing the gases generated at each electrode, you can visualize and verify the migration of ions during electrolysis. Remember to exercise caution and perform this experiment under adult supervision, as electrolysis involves the use of electricity.