Half-Equations
Chemistry: Cambridge International GCSE Supplement, topic 4.1.9
Half Equations
During electrolysis, different reactions take place at the different electrodes. Half equations show the reactions that happen at each electrode. The electrolysis of lead bromide is an example of this:
At the anode (positive electrode)
- Oxidation reactions happen i.e. negatively charged ions lose electrons.
- E.g. 2Br- → Br2 + 2e-
At the cathode (negative electrode)
- Reduction reactions happen i.e. positively charged ions gain electrons.
- E.g. Pb2+ + 2e- → Pb
Test yourself on Half-Equations
What are the half equations for the electrolysis of lead bromide (PbBr2)?
What type of reaction happens at the anode (positive electrode) during electrolysis?
What type of equations are used to describe the different reactions taking place at each electrode?