Question

A $0.1\text{M}$ solution of a weak acid $HA$ is titrated by $NaOH$ slowly. The titration curve observed is given below. $k_a=4\times {10}^{-5}$ at $25{}^{\circ }\text{C}.$ The correct observation for the curve will be:

• A. Solution will make buffer before equivalence point
• B. pH of solution at equivalence point is $5.6$
• C. pH of solution at equivalence point is $7$
• D. Salt hydrolysis isn't suitable to predict the pH of equivalence point

Answer 1

The correct option is A Solution will make buffer before equivalence point

$HA+NaOH\leftrightharpoons NaA+H_{2}O$
Solution will make buffer before equivalence point since before equivalence point both $HA$ and $NaA$ are present.
The pH of solution at equivalence point is almost $10$.
In this process, water is released. So, pH can be predicted by salt hydrolysis.