# What is the oxidation number for all elements of AsO4^3-?

Apr 11, 2017

Oxygen is -2 (by assignment) and As is +5

#### Explanation:

The convention is to assign -2 to oxygen when it appears in any compound (except for ${H}_{2} {O}_{2}$ where it is -1).

Then, we require that the total of all oxidation numbers in any molecule or ion add up to the real electric charge on that particle.

Now, you solve like an algebra problem:

As + 4(-2) = -3

As = -3 +8 = +5