Question

Identify the oxidant and reductant in the reactions:

I₂(g) + H₂S(g) → 2HI(g) + S(s)

Answer 1

Writing the ON of all the atoms above their symbols, we have

The ON of I₂ decreases from zero in I₂ to -1 in HI, therefore, I₂ is reduced and hence it acts as on oxidant. 

The O.N. of S increases from -2 in H₂S to zero in S, therefore, H₂S is oxidized and hence it acts as the reductant.