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+ Nitric acid
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Mats Andersson

What is the nitric acid and water reaction?

David Min  Follow

Nitric acid with water reacts as follows:
HNO3 + H2O ⇌ H3O+ + NO3−

Nitric acid is a relatively strong acid, meaning it tends to ionize almost completely in aqueous solution.

H2 acts as a base to abstract an H+ from the nitric acid. The resulting H3O+, hydronium, is the conjugate acid, while the NO3-, nitrate, is the conjugate base (this is the molecule of nitric acid, but stripped of its H+.

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Chris Conrad  Follow

Nothing special. Simply, the acid’s concentration becomes diluted. However, there is an acid base reaction that Nitric acid is constantly undergoing, which is:

HNO3 + H2O -> <- (equilibrium arrow notation) NO3- + H3O+

I say always because Nitric acid is aqueous, meaning that there is nothing such as “pure Nitric acid” . Nitric acid is formed when nitrogen dioxide (NO2) is absorbed into water, and there is a specific thermodynamic limit after which NO2 can no longer be absorbed. Industrially, Nitric acid’s concentration can go as high as 95% (which is called fuming Nitric acid).

So when u add water to Nitric acid, you aren’t changing the amount of NO2 in the solution, thus the absolute amount of HNO3 will remain constant. But the concentration will decrease, the pH will increase and the acid becomes weaker.

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