# Why do we need sulfuric acid in reducing nitric acid?

Why do we need sulfuric acid in the left part of the formula? Wouldn't FeSO4 reduce nitric acid without the sulfuric acid taking part?

P.S.

I was answered that a milder form of the reduction would still take place:

Is that right?

So we need the acid to make the reduction more advanced, all the way to N(2+) from N(5+)? How does it work?

• Sounds about right. Now, this is essentially the same reaction, but with different consequences. If you have excess $\ce{HNO3}$, it will (sort of) bring your $\ce{NO}$ back to $\ce{NO2}$. If you don't, it won't. – Ivan Neretin Feb 27 '16 at 19:26