MCQ
The $pH$ of a simple sodium acetate buffer is given by $pH = p{K_a} + \log \frac{{[Salt]}}{{[Acid]}}$ ${K_a}$ of acetic acid $ = 1.8 \times {10^{ - 5}}$ If [Salt] = [Acid] = $0.1 \,M$, the $pH$ of the solution would be about
  • A
    $7$
  • $4.7$
  • C
    $5.3$
  • D
    $1.4$

Answer

Correct option: B.
$4.7$
(b) [Salt]= $0.1 \,M$, [Acid]= $0.1\, M$

${K_a} = 1.8 \times {10^{ - 5}}$ ; $pH = - \log {K_a} + {\rm{log}}\frac{{{\rm{[Salt]}}}}{{{\rm{[Acid]}}}}$

$ = - {\rm{log}}\,1.8 \times {10^{ - 5}} + {\rm{log}}\frac{{0.1}}{{0.1}}$$ = - {\rm{log}}\,\,1.8 \times {10^{ - 5}}$

$pH = 4.7$.

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