In the electrolysis of molten potassium bromide (K2Br), the compound dissociates into its constituent ions, potassium ions (K+) and bromide ions (Br-). The half-reactions at each electrode can be determined by considering the oxidation and reduction processes that occur.
At the cathode (negative electrode), reduction takes place. In this case, potassium ions (K+) are reduced to form potassium metal (K) as follows:
2K+ + 2e- → 2K
The half-equation for the reduction reaction at the cathode is:
2K+ + 2e- → 2K
At the anode (positive electrode), oxidation occurs. Here, bromide ions (Br-) are oxidized to form bromine gas (Br2):
2Br- → Br2 + 2e-
The half-equation for the oxidation reaction at the anode is:
2Br- → Br2 + 2e-
To summarize:
Cathode (Reduction): 2K+ + 2e- → 2K Anode (Oxidation): 2Br- → Br2 + 2e-