I'm supposed to balance a redox reaction that occurs in an acidic solution.

Question

I already balanced it(h**p://img148.imageshack.us/img148/4304/redoxht8.jpg), but how do I tell if a half-reaction is oxidation or reduction? I know an oxidation reaction loses electrons, and an reduction reaction gains electrons, but how do I tell from the reaction?

Answer 1

If electrons are added to the left side of the half reaction, it is a reduction. In the reaction you are referring to, ClO₃^- is reduced and As₂S₃ is oxidized.

Answer 2

I see. TY.