Answer:
hydrolysis of the resulting salt
Explanation:
The pH at the equivalence point of a titration is not always 7.0 due to the hydrolysis of resulting salt.
The pH at the equivalence point of a titration involving a strong acid and a strong base will be 7 because the conjugate base of the salt formed will be too weak to react with water. For example, the titration of HCl and NaOH:
[tex]HCl + NaOH --> NaCl + H_2O[/tex]
In the case of strong acid and weak base, the pH at the equivalence point will be acidic because the salt formed would dissociate and react with water. For example, the titration of HCl with NH3:
[tex]NH_3+HCl-->NH_4Cl[/tex]
The resulting salt dissociates in water and releases proton to form an acidic endpoint.
[tex]NH_4^{+} + H_2O --> H_3O^+ + NH_3[/tex]
For weak acid and strong base, the pH at the equivalence point will be alkaline because the resulting salt dissociates in water to form an alkaline solution.
[tex]NaOH + CH_3COOH --> CH_3COONa + H_2O[/tex]
[tex]CH_3COO^- + H_2O --> CH_3COOH + OH^-[/tex]
