Hi all,
I was wondering if anyone could tell me the conditions required for the hydrolysis of nitrogen dioxide, i.e., when nitrogen dioxide reacts with water to form nitric acid and nitrogen monoxide. At what temperature and/or pressure is this spontaneous? I understand that nitrous acid is formed, but its instability leads to the creation of the latter products.
Thank you so much!
The decisive quantity for spontaneity of a reaction is normally the Gibbs free energy G or, equivalently, the equilibrium constant K. These quantities are connected via ΔG=-RTlnK and you have ΔG=ΔH-TΔS with the enthalpy H and entropy S.
In order to check your system, you can calculate ΔH and ΔS with tabulated data, e.g. from the NIST chemical webbook (at least while it still exists), and proceed to ΔG.
The temperature dependence of ΔG is given be integrating the specific heats of the components with respect to the temperature.
The hydrolysis of NO2 is described in textbooks
Alyssa Ishchenko , yours " when nitrogen dioxide reacts with water to form nitric acid and nitrogen monoxide." This reaction
2 NO 2 + H 2O → HNO 3 + NO
is not balanced!
Dear Jürgen Weippert , you did not mention that the chemical reaction between nitrogen dioxide and water is: 2 NO 2 ( g ) nitrogen dioxide + H 2 O ( l ) water → HNO 3 ( aq ) Nitric acid + HNO ( aq ) Nitrous acid.
Hi Alyssa Ishchenko
In the production of 68 wt% nitric acid, the NO2 absorption column is typically 30C and 10 barg. Air is added to convert NO to NO2. Cooler temperature and higher pressure increase conversion but also increase compression and cooling costs.
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