A physician wishes to prepare a buffer solution at pH = 3.58 that… - Vidyadip

MCQ

A physician wishes to prepare a buffer solution at $pH = 3.58$ that efficiently resists changes in $pH$ yet contains only small concentration of the buffering agents. Which of the following weak acids together with its sodium salt would be best to use

A
$m - $chlorobenzoic acid $(p{K_a} = 3.98)$
B
$p - $chlorocinnamic acid $(p{K_a} = 4.41)$
✓
$2,\,\,5 - $dihydroxy benzoic acid $(p{K_a} = 2.97)$
D
Acetoacetic acid $(p{K_a} = 3.58)$

✓

Answer

Correct option: C.

$2,\,\,5 - $dihydroxy benzoic acid $(p{K_a} = 2.97)$

(c) $pH = p{K_a} + {\rm{log}}\frac{{{\rm{[Salt]}}}}{{{\rm{[Acid]}}}}$. For small concentration of buffering agent and for maximum buffer capacity $\frac{{{\rm{[Salt]}}}}{{{\rm{[Acid]}}}} \approx 1$.

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