Question

The pH of buffer solution prepared by mixing 50 ml of 0.2 M $C{H}_{3}COOH$ and 25 ml of $C{H}_{3}COONa$ is 4.8 what is the concentration of $C{H}_{3}COONa$?$P_{ka}$ of $C{H}_{3}COOH$=4.8

• A. 0.2 M
• B. 0.4 M
• C. 0.5 M
• D. 0.3 M

Answer 1

The correct option is B 0.4 M

$pH=pKa$ when conc. of $\left[C{H}_{3}COOH\right]=pC{H}_{3}COONa]$
$\left[C{H}_{3}COOH\right]=\frac{(0.2\times 50)minute}{75mL}=0.133$
$\%\left[C{H}_{3}COONa\right]=\frac{x\times 25}{75}$
$\frac{0.133\times 75}{25}=x$
$x=0.399$
$x\approx 0.4M$