In electrolysis , which reaction does occur on the cathode , half oxidation reaction or reduction ?
By definition, reduction occurs at the cathode.
In electrolysis, the reaction that occurs at the cathode depends on the specific ions present in the electrolyte solution. The cathode is the electrode connected to the negative terminal of a power source and is where reduction reactions typically occur.
Reduction involves the gain of electrons, so if a positive ion is present in the electrolyte solution, it will undergo reduction at the cathode. This reduction reaction can be considered as a half-reaction in which the positive ion gains electrons to form a neutral species.
To determine which half-reaction occurs at the cathode during electrolysis, you need to consider the specific ions in the electrolyte. For example, if the electrolyte is a solution of copper sulfate (CuSO4), the copper ion (Cu2+) would be attracted to the cathode and undergo reduction. The half-reaction at the cathode would be:
Cu2+ + 2e- -> Cu
The reduction of Cu2+ to Cu indicates the gain of two electrons by each copper ion.
So, in short, during electrolysis, reduction reactions occur at the cathode, and the specific reduction reaction depends on the ions present in the electrolyte.