[Boxxxed]

As2O3(s) + NO3-(aq) → H3AsO4(aq) + HNO2(aq)
Write which element is reduced: __________ which element is oxidized? _________

I have 7H+ + As203 + NO3- |---------> 2H3As04 + HN02

Arsenic gains 16 electrons, nitrogen gains 2 electrons from my calculations. If oxygen and hydrogen aren't oxidized what is?

[ooosh]

The oxidized element is As ,which from As2O3(+3) to H3AsO4 (+5),and the reduced element element is N from NO3^-(+5) to HNO2(+3).Then you can do the balancing job.

[Boxxxed]

Wow, that was easy, guess I just had a major brain fart

[Boxxxed]

I have

As203 + 2NO3-  >>>>>>  2H3As04 + 2HNO2

It's balanced for number of electrons, how do I balance for oxygen and hydrogen? Do I just add H20 and H+ ?

Also, I forgot the 2 in As2O3 in the original post.

[ooosh]

I can not give you the answer,but you almost get your answer.There are three basic rules for balancing reaction:law of conservation of mass , charge conservation and materials conservation.

[Borek]

Do I just add H20 and H+ ?

In a correct way. But yes, that's what you should do now.

Note that whether you should use H⁺ or OH^- depends on the solution pH. You are not told what is pH solution in this case, but as one of the products listed is H₃AsO₄ - fully protonated acid - you may assume pH is low.