Question

What is the oxidation state of sulfur in the compound H2SO4 (sulfuric acid), and what is its change in oxidation state during the reaction as it is reduced to H2S (hydrogen sulfide) in a redox reaction with hydrogen gas?

Answer 1

In the compound H2SO4  sulfuric acid , the oxidation state of sulfur is +6. During the redox reaction, sulfur is reduced from H2SO4 to H2S. In H2S, the oxidation state of sulfur is -2. The change in oxidation state for sulfur during this reaction is a decrease of 8 units, from +6 in H2SO4 to -2 in H2S.