AQA GCSE FOUNDATION Chemistry: Electrolysis of Solutions

Electrolysis of Solutions: AQA GCSE Foundation Chemistry

Electrolysis is the process of using electricity to break down a compound. This tutorial focuses on the electrolysis of solutions, particularly copper(II) chloride (CuCl?).

Setting Up the Experiment

1. Prepare the Electrolyte: Dissolve copper(II) chloride (CuCl?) in water to create a solution.
2. Connect the Circuit:
   • Connect a battery or power supply to two inert electrodes (e.g., carbon or platinum).
   • Ensure the electrodes are immersed in the copper(II) chloride solution.
3. Observe and Record: Carefully observe any changes at the electrodes, particularly gas evolution.

Reactions at the Electrodes

Anode (Positive Electrode):

• Oxidation: At the anode, negatively charged ions (anions) lose electrons and are oxidized.
• Reaction:
  • 2Cl?(aq) ? Cl?(g) + 2e?

Cathode (Negative Electrode):

• Reduction: At the cathode, positively charged ions (cations) gain electrons and are reduced.
• Reaction:
  • Cu²?(aq) + 2e? ? Cu(s)

Interpreting the Observations

1. Gas Evolution: Chlorine gas (Cl?) is produced at the anode, recognized by its pale green colour and pungent odour.
2. Copper Deposition: Copper metal (Cu) is deposited on the cathode, resulting in a reddish-brown coating.

Influence of the Reactivity Series

The reactivity series helps determine the products of electrolysis. Copper is less reactive than hydrogen, while chlorine is more reactive than oxygen. Therefore:

• Copper ions are reduced at the cathode.
• Chloride ions are oxidized at the anode.

Summary

Electrolysis of copper(II) chloride solution produces chlorine gas at the anode and copper metal at the cathode. This process illustrates the principles of oxidation and reduction, the importance of the reactivity series in predicting electrolysis products, and the fundamental role of electricity in chemical reactions.