Question

A weak acid is titrated with a weak base. Consider the following statements regarding the $pH$ of the solution at the equivalence point :
(i) $pH$ depends on the concentration of acid and base.
(ii) $pH$ is independent of the concentration of acid and base
(iii) $pH$ depends on the $pK _{ a }$ of acid and $pK _{ b }$ of base.
(iv) $pH$ is independent of the $pK _{ a }$ of acid and $pK _{ b }$ of base.
The correct statements are :-

• A. only (i) and (iii)
• B. only (i) and (iv)
• C. only (ii) and (iii)
• D. only (ii) and (iv)

Answer 1

Answer: (C)

For salts of weak acid and weak base
$pH =7+\frac{1}{2}\left( pK _{ a }- p K _{ b }\right)$
$pH$ is independent of concentration of acid and base