Question

Why do solutions of a strong acid, and a strong base, which contain equimolar \[{H_3}{O^ + }\] and \[O{H^ - }\] , when mixed give rise to a solution that is pH neutral?

Answer 1

Hint: Strong acid is an acid that can easily or completely dissociate into ions to release \[{H^ + }\] ions. Strong base is a base that can easily give hydroxide ion or abstraction of protons. pH is defined as the negative logarithm of the hydrogen ion concentration. Equimolar concentrations of \[{H_3}{O^ + }\] and \[O{H^ - }\]gives a neutral solution.

Complete answer:
pH is defined as the negative logarithm of the hydrogen ion \[\left[ {{H^ + }} \right]\] concentration the equation can be written as \[pH = - \log \left[ {{H^ + }} \right]\]
Given that a solution of a strong acid, and a strong base are taken with equimolar concentrations of \[{H_3}{O^ + }\] and \[O{H^ - }\] .
Strong acid and strong base with equimolar concentrations of \[{H_3}{O^ + }\] and \[O{H^ - }\] means the concentrations of strong base and strong acid are equal.
\[{H_3}{O^ + }\] known as hydronium ions that can be formed by reacting \[{H^ + }\] with \[{H_2}O\] . The term \[{H_3}{O^ + }\] means it is an acidic compound. Hydroxide ion \[\left( {O{H^ - }} \right)\] is released from basic compounds.
When a solution with equimolar concentrations of \[{H_3}{O^ + }\] and \[O{H^ - }\] are taken it results in the formation of two water molecules. The chemical reaction will be as follows:
\[{H_3}{O^ + } + O{H^ - } \to 2{H_2}O\]
Thus, the solution will be a neutral pH solution as water is formed.

Note:
The negative part in the strong acid and the positive part in the strong base reacts to give a corresponding salt. Whereas the hydronium ion and hydroxide ion react to give two molecules of water which has a pH value of \[7\] and can be a neutral solution.