# Reaction between an acid and acid

My initial thought was that the stronger acid will act as an acid and the weaker acid as base like the reaction between $$\ce{H2SO4}$$ and $$\ce{HNO3}$$ but in this reaction there is a lone pair available for protonation, what if the lone pair was not present , will the reaction still occur? Is the answer dependent on what the acids exactly are?

• Can you give an example of acid where the lone pair is not present? – Ivan Neretin May 21 '19 at 11:24
• I meant an acid in which lone pair is unavailable like in Ammonium ion(NH4+). – FullBridge May 21 '19 at 11:44
• OK, then there will be no reaction of this type. – Ivan Neretin May 21 '19 at 11:55
• Being an acid and ability of acting as base are 2 independent properties. The same for bases and their ability to act as acids. – Poutnik May 21 '19 at 11:59
• So a stronger acid cannot protonate a weaker one(in general)? – FullBridge May 21 '19 at 12:00

In the case of $$\ce{HNO3}$$ and $$\ce{H2SO4}$$, the proton from sulphuric acid protonates the $$\ce{-OH}$$ group of $$\ce{HNO3}$$ , which gives $$\ce{NO2+}$$ , $$\ce{HSO4-}$$ and water. This mixture of nitric acid and sulphuric acid is widely used as a nitrating mixture for nitration of aromatic compounds.