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Is there a chemical reaction between nitric acid and acetic acid?

The main reason I am asking this question because my lab throws away residues of both of these two ($\pu{1 M}$ concentration each) in the same bin, and I am worried about the safety.

I have searched the internet and textbooks to find the chemical reaction between nitric acid $(\ce{HNO3})$ and acetic acid $(\ce{CH3COOH})$.

ChatGPT says it is the following:

$$\ce{2HNO3​+CH3​COOH→2NO2​+2H2​O + CO2}$$

Is this true? Can someone provide a source for this?

All universities say these two chemicals are incompatible. Here's an example from University of Berkely where it says:

"For example, both nitric and perchloric acids are incompatible with organic acids (such as acetic acid) and should not be stored together."

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    $\begingroup$ I wouldn't expect much happening with 1 M solutions. Acetic acid is even used as the solvent for nitration or arenes (chemistry.stackexchange.com/questions/122861). $\endgroup$
    – andselisk
    Commented Jun 5 at 9:18
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    $\begingroup$ Thank you for your answer. Then why do so many universities have published literature of not storing these two together? $\endgroup$
    – urxwrt
    Commented Jun 5 at 9:20
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    $\begingroup$ Probably they refer to acetic anhydride and concentrated nitric acid, that would be a totally different story. And it's just a good practice to keep away oxidizers from any organic stuff regardless of their concentrations. $\endgroup$
    – andselisk
    Commented Jun 5 at 9:44
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    $\begingroup$ So much for ChatGPT. It needs to learn how to balance equations. $\endgroup$
    – user55119
    Commented Jun 5 at 16:26
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    $\begingroup$ A mixture of phosphoric, acetic, and nitric is a long-standard wet etchant for aluminum thin films. Even sold in bottles for that purpose. $\endgroup$
    – Jon Custer
    Commented Jun 7 at 14:01

2 Answers 2

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When I go through the OP's question and comments by my collogues, it's evident that OP is not simply satisfied with the comments even though andselisk's comment is the clearly answer to OP's major concern in laboratory safety. So I thought this answer may be good enough to satisfy OP's concern about the quote from University of Berkley website, which states:

Both nitric and perchloric acids are incompatible with organic acids (such as acetic acid) and should not be stored together.

According to California State University (Northridge) website, the following reduction potentials for the given half reactions have been listed: $$\ce{CO2 (g) + 2H+ + 2e- <=> HCOOH} \qquad E^\circ =\pu{-0.114 V} \tag1$$ $$\ce{HClO + H+ + e- <=> 1/2Cl2 (g) + H2O} \qquad E^\circ =\pu{+1.630 V} \tag2$$ $$\ce{ClO4- + 2H+ + 2e- <=> ClO3- + H2O} \qquad E^\circ =\pu{+1.226 V} \tag3$$ $$\ce{NO3- + 2H+ + e- <=> 1/2N2O4 (g) + H2O} \qquad E^\circ =\pu{+0.798 V} \tag4$$

According to equations $(1)$ and $(3)$ (formic acid and perchloric acid mixture): $$\ce{ClO4- + HCOOH -> CO2 (g) + ClO3- + H2O} \qquad E^\circ_\mathrm{cell} =\pu{+1.340 V} \tag5$$ Thus, according to the redox equation $(5)$, a mixture of formic acid and perchloric acid would react spontaneously to produce gaseous product $(\ce{CO2})$ slowly to increase pressure in (obviously) closed containers, which is a safety hazard.

Similarly, according to equations $(1)$ and $(4)$ (formic acid and nitric acid mixture): $$\ce{2NO3- + 2H+ + HCOOH -> N2O4(g) + CO2(g) + 2H2O} \qquad E^\circ_\mathrm{cell} =\pu{+0.921 V} \tag6$$ Therefore, according to the redox equation $(6)$, a mixture of formic acid and nitric acid would also react spontaneously to produce two gaseous products $(\ce{CO2} \text{ & } \ce{N2O4})$ slowly to increase pressure in (obviously) closed containers, which is even a higher safety hazard considering toxic nature of $\ce{N2O4}$.

Further, according to equations $(1)$ and $(2)$, formic acid and hypochlorous acid mixture in acidic conditions also a hazardous mixture. I mentioned this here because we commonly use bleach solution $(\ce{NaClO})$ to oxidized organic compounds in undergraduate teaching labs.


Late edit:
The carbonic acid mentioned in my answer is formic acid. I could not find the reduction potential for acetic acid. However, I assumed it should be in close proximity to formic acid according to Wikipedia, which has listed the half reaction of acetic acid in biological systems as follows: $$\ce{CH3COOH + 2H+ + 2e- <=> CH3CHO + H2O} \qquad E^\circ = \pu{-0.58 V} \tag7$$ Yet, Mithoron's comment, "Acetic is nowhere near as easily oxidizable. It's the formyl group in formic that makes it reactive.," made me think about it a little further. For example, let's look at acetic acid in nitric acid situation. The redox reaction (from equations $(4)$ and $(7)$) is:

$$\ce{2NO3- + 2H+ + CH3CHO <=> CH3COOH + N2O4(g) + H2O} \qquad E^\circ_\mathrm{cell} = \pu{1.378 V} \tag8$$ This means a mixture of acetaldehyde and nitric acid is spontaneously making a gaseous mixture, not acetic acid and nitric acid!

Note: According to some educators, ChatGPT has some issues on accuracy (Ref.1).


References:

  1. Brandon J. Yik and Amber J. Dood, "ChatGPT Convincingly Explains Organic Chemistry Reaction Mechanisms Slightly Inaccurately with High Levels of Explanation Sophistication," J. Chem. Educ. 2024, 101(5), 1836–1846 (https://doi.org/10.1021/acs.jchemed.4c00235).
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    $\begingroup$ Acetic is nowhere near as easily oxidisable. It's the formyl group in formic that makes it reactive. CH3 isn't oxidised so easily. $\endgroup$
    – Mithoron
    Commented Jun 6 at 16:01
  • $\begingroup$ Thank you for your detailed answer. If assuming as similar reaction with acetic acid, why did you say that andselisks answer is correct. Just due to molarity? How can we know at what point molarity increases the saftey risk? $\endgroup$
    – urxwrt
    Commented Jun 6 at 16:52
  • $\begingroup$ What I meant is andselisk's comment about dilute solution is correct. Dilute nitric acid is not a oxidizer. See Mithoron's comment above for acetic acid. I'm going to change my answer accordingly. $\endgroup$ Commented Jun 6 at 17:13
  • $\begingroup$ @MathewMahindaratne Nitric acid is an oxidizer at any concentration. $\endgroup$
    – andselisk
    Commented Jun 7 at 5:59
  • $\begingroup$ Three ! Equation ($5$) from Mathew Mahindaratne has three mistakes : one $\ce{H}$ missing in $\ce{HClO4^-}$, one Carbon missing in $\ce{HOOH}$, and one double Plus sign at right. It should be written : $\ce{ClO4^- + HCOOH -> CO2(g) + ClO3^- + H2O}$ $\endgroup$
    – Maurice
    Commented Jun 7 at 8:48
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Concentrated nitric or perchloric acids and their salts will oxidize almost any organic material with some heat or catalyst. Oxidizers and reducers must not be stored together; special care is needed for compounds such as ammonium nitrate. Waste streams should not mix oxidizers with reducers or flammable materials. Before disposal oxidizers, reducers, acids, bases must be reacted and neutralized. Your lab's disposal practices should be examined and codified. In my 50+ years as an industrial and research chemist I have seen too many accidents from "safe" procedures with cavalier approach or inattention to safety.

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