# Question #707a3

Sep 25, 2017

Sulphuric acid

#### Explanation:

Sulphuric acid is a strong mineral acid (one of the strongest), as it typically produces more than one mole of hydrogen ions in solution per mole of acid.

This is because is dissociates (splits up) in two stages in water. In the first equilibrium reaction, one hydrated ${H}^{+}$ ion is produced leaving the hydrogen sulphate ion, $H S {O}_{4}^{-}$ - this reaction goes pretty much to completion. There is however a second equilibrium reaction, where the $H S {O}_{4}^{-}$ ion dissociates further to produce another ${H}^{+}$ ion and the sulphate ion, $S {O}_{4}^{2 -}$. This second equilibrium does not go to completion. Thus more than one mole of ${H}^{+}$ ions per mole of acid.

Sulphuric acid is so strong that it is able to force nitric acid to act as a base. This reaction is used in organic chemistry to nitrate especially aromatic compounds.

Sulphuric acid is extremely useful industrially and is made by the Contact process where sulphur is first burned in air to produce sulphur dioxide which is then further reacted with oxygen in the presence of a vanadium pentoxide catalyst to produce sulphur trioxide. This is then dissolved in concentrated sulphuric acid to make a thick oily substance called oleum (${H}_{2} {S}_{2} {O}_{7}$) which is finally added carefully to water (not the other way round) to make a greater volume of concentrated sulphuric acid.