Define pH of a solution.

Explanation

It can be shown that pH of different kinds of salts can be given by the following expressions:
For salts of weak acids - strong bases : pH = `7+1/2[pK_(a)+logc]`
For salts of strong acids - weak bases : pH = `7-1/2[pK_(a)+logc]`
For salts of weak acids - weak bases : pH = `7-1/2[pK_(a)+pK_(b)]`
where the terms `pK_(a)andpK_(b)` have the usual meanings, and c is the concentration of the salt solution.
Hydrolysis of weak acid - strong base salt is shown by
`A^(-)+H_(2)OhArrHA+OH^(-)`
Example : `CH_(3)COONa+H_(2)OhArrCH_(3)COOH+NaOH^(-)`
Hydrolysis constant `K_(b)` can be shown to be equal to `K_(w)/K_(a)`, and the degree of hydorlysis x = `sqrt(K_(b)/c)`.
Similar derivations can be done for the other types of salts also. The outocomes of such derivations are summerised below.