Why doesn't $\ce{NO}$ (nitric oxide) react with water? I know it is a neutral oxide, but I'm really curious as to why that is. Why will $\ce{NO}$ not react with $\ce{H2O}$?

  • 6
    $\begingroup$ Why would it? Normally we explain why things happen, and not why they don't. $\endgroup$ Commented Mar 22, 2017 at 22:31
  • $\begingroup$ Think about it, oxides dissolve in water to give their corresponding acids or bases. Here, what acid would you get, and how stable would its conjugate base ? i believe now you have your answer $\endgroup$
    – SubZero
    Commented Mar 23, 2017 at 7:26
  • 3
    $\begingroup$ @IvanNeretin what is "normal"? $\endgroup$
    – ParaH2
    Commented Mar 23, 2017 at 8:22

2 Answers 2


Although nitric oxide is thermodynamically unstable, it is kinetically stable as its decomposition rate is very slow[ref] and so it is considered stable and won't normally react to anything.

So, nitric oxide wouldn't normally hydrolyze easily. But in the presence of air, it forms nitrous acid $(\ce{HONO})$:

$$\ce{4NO + O2 + 2 H2O -> 4 HNO2}$$

However, nitrous acid is very unstable and quickly disproportionates:

$$ \begin{align} \ce{2 HNO2 &-> NO2 + NO + H2O &(cold dil. soln.)}\\ \ce{3 HNO2 &-> HNO3 + 2 NO + H2O &(warm conc. soln.)} \end{align}$$

Since $\ce{HNO2}$ is required to prepare diazonium salts (a versatile compound in organic chemistry), it is prepared in-situ by reaction of $\ce{NaNO2}$ and $\ce{HCl}$. Due to its instability, it is prepared for one-time use and is not stored for further preparations.

Reference: J. Phys. Chem., 1958, 62 (3), pp 360–361 https://doi.org/10.1021/j150561a030


I have also heard about a disproportion reaction which happens with a productivity of around $0,01 \%$ as,

$$\ce{4NO + H2O -> N2O + 2HNO2}$$

  • $\begingroup$ Hi thanks for your contribution. Though in such cases, it's much better to cite your source as well. A research paper or a famous textbook generally works. Thanks! $\endgroup$ Commented Apr 24, 2018 at 9:16
  • $\begingroup$ My chemistry teacher, a professor at my university told me about this reaction a long long time ago. Since then the only source where I could find this reaction was a Russian website which also contains a vast database of known chemical reactions. There is no original source, there's a mistake (HNO3 instead of HNO2) and the only note is "almost no reaction". Sorry, it's a really interesting reaction and I keep wondering about its mechanism but I just fail to find any papers or books, at least on the Internet. $\endgroup$
    – user63281
    Commented Apr 24, 2018 at 23:03
  • $\begingroup$ No worries, and I appreciate your response. But in this case, I think it's rather better if you instead ask a new question, looking for proper citation for the reaction. We support reference-request as well, so it wouldn't be a problem :-) $\endgroup$ Commented Apr 25, 2018 at 0:23

Your Answer

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

Not the answer you're looking for? Browse other questions tagged or ask your own question.