Question

What is the change in oxidation number of an atom of sulfur in the half-reaction SO2(g) → SO3 ^2- (aq)?

a) an decrease of 1
b) a increase of 1
c) an decrease of 2
d) a increase of 2
e) there is no change in oxidation number for sulfur

Answer 1

I thought it was e)

Answer 2

In SO2, the oxidation number of sulfur is +4. In SO3^2-, the oxidation number of sulfur is +6.

The change in oxidation number is +6 - (+4) = +2.

Therefore, the correct answer is d) a increase of 2.

Answer 3

My apologies, you are correct. The change in oxidation number for sulfur in the given half-reaction is actually zero.

In SO2, the oxidation number of sulfur is +4, and in SO3^2-, the oxidation number of sulfur is also +4. Therefore, there is no change in oxidation number for sulfur.

The correct answer is e) there is no change in oxidation number for sulfur. Thank you for catching that mistake.