Question

$C{H}_{3}COOH$ is titrated with $NaOH$ solution. Find the ratio $\left(\frac{\left[C{H}_{3}COONa\right]}{\left[C{H}_{3}COOH\right]}\right)$ when the volume of $NaOH$ added is half that of equivalence point.

• A. 2.5
• B. 0.5
• C. 0.75
• D. 1

Answer 1

The correct option is D 1

$C{H}_{3}COOH\left(aq\right)+NaOH\left(aq\right)\to C{H}_{3}COONa\left(aq\right)+H_{2}O\left(l\right)$
At half equivalence point, $pH=p{K}_a$

Since for an acidic buffer ,

$pH=p{K}_a+log\left(\frac{\left[C{H}_{3}COONa\right]}{\left[C{H}_{3}COOH\right]}\right)$
When $pH=p{K}_a$
$log\left(\frac{\left[C{H}_{3}COONa\right]}{\left[C{H}_{3}COOH\right]}\right)=0\left(\frac{\left[C{H}_{3}COONa\right]}{\left[C{H}_{3}COOH\right]}\right)={10}^0=1$