# What are the sulfur oxidation states in sulfuric acid and sulfurous acid?

Aug 26, 2017

For ${H}_{2} S {O}_{4}$ we gots $S \left(V I\right)$.

#### Explanation:

For ${H}_{2} {S}_{2} {O}_{3}$ we gots ${S}_{\text{average}} \left(I I\right)$. As always the sum of the oxidation is equal to the charge on the ion/molecule, here neutral.

For ${H}_{2} {S}_{2} {O}_{3}$ I like to think that ONE of the oxygens in ${H}_{2} S {O}_{4}$ has been REPLACED by a sulfur atom, and thus assumes the SAME oxidation state (they are both Group VI elements). And so, by this formalism, we gots $S \left(- I I\right)$ and $S \left(+ V I\right)$.

Of course the average oxidation state is ......

$\frac{S \left(- I I\right) + S \left(+ V I\right)}{2} = + I I$,

.........but sometimes the individual assignment of oxidation numbers in poly-sulfur compounds is useful.