Question

If for the reaction PbO₂ → PbO, ΔG° < 0 

And for the reaction SnO₂ → SnO, ΔG° > 0 

What are the most probable oxidation states of Pb and Sn?

Answer 1

Oxidation states of the elements in the following compounds are

Since PbO₂ → PbO change is accompanied by decrease in free energy it is a spontaneous change hence Pb in +2 state is more stable than in +4 state.