Why does water have a leveling effect on acids and bases?

[brainyman89]

can somebody explain to me the reason of leveling effect of water in details and numbers? thanks in advance.

 

[symbolipoint]

Such bases as NaOH, or KOH, which are stronger bases than water, will give OH- ions in water. Also, water itself dissociates to give small amounts of H3O⁺ and OH^-. If a stronger base than H2O is dissolved in water, it will produce OH^- and a weak acid.

Assume MA is a very soluble salt, and that A- is a stronger base than H2O.
H₂O + M⁺ + A^- -------> M⁺ + OH^- + HA
The OH^- is the base now, and HA is a weak acid, having much less effect on pH. Also, the HA might not ordinarily be thought of as an acid; the A^- merely accepted a hydrogen ion as it formed a more neutral molecule.