1
$\begingroup$

So I have a home lab setup and recently found myself in need of some nitric acid. I could just buy some, but I thought it would be a useful exercise to make my own. I have plenty of nitrate salts around, as well as plenty of unused ~30% sulfuric acid (battery acid refills, fresh out of the box so there's no lead etc in it).

I know distillation of a mixture of a nitrate salt (ex. NaNO3) in sulfuric acid should yield nitric acid, but all the protocols I've found call for concentrated H2SO4. Would ~30% work? I know "concentrated" sulfuric acid usually means >90% if not fuming, but as long as I use stoichiometric ratios of the nitrate and the sulfuric acid, the reaction should still proceed fine, correct? Obviously the nitric acid will be more dilute, but I don't need very concentrated nitric acid anyway.

I realize I can distill the sulfuric aid to concentrate it, but I haven't done that before and would like to minimize the number of "dangerous" distillations I do. My vacuum pump is pretty shoddy and distillation of H2SO4 at ambient pressure requires so much heat, it just seems like an unnecessary risk if 30% would work.

Improve this question
$\endgroup$
2
  • $\begingroup$ $1$ kg $30$% sulfuric acid contains $300$ g $\ce{H2SO4}$ (= about $3$ moles). It may react with $\ce{NaNO3}$ according to : $$\ce{H2SO4 + NaNO3 -> NaHSO4 + HNO3}$$ and may produce $3$ moles or $3·63 = 189$ g $\ce{HNO3}$, plus $700$ g water. The solution contains also $3$ moles $\ce{NaHSO4}$ ($360$ g). It is hard to describe the composition of the vapor that will distill out of such a mixture. It should be a mixture $\ce{HNO3 + H2O}$. In the beginning it should be nearly pure water. But slowly the vapor will contain more nitric acid. But at what temperature and how much ? $\endgroup$
    – Maurice
    Oct 19, 2020 at 12:42
  • $\begingroup$ Related $\endgroup$
    – Poutnik
    Oct 19, 2020 at 13:00

0

Reset to default

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct.

Browse other questions tagged or ask your own question.