A physician wishes to prepare a buffer solution at $\mathrm{pH}=3.85$ that efficiently resists chang

Question

A physician wishes to prepare a buffer solution at $\mathrm{pH}=3.85$ 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?\

Professor PC Thomas Classes · Answer

(b) : pH of an acidic buffer solution is given by Henderson equation :\ $\mathrm{pH}=\mathrm{p} K_{a}+\log \frac{[	ext { Salt }]}{[	ext { Acid }]}$\ Its buffer capacity $=\mathrm{p} K_{a} \pm 1$\ Since a buffer solution is more effective in pH range $\mathrm{p} K_{a} \pm 1$ therefore, the weak acid having $\mathrm{p} K_{a}=3.58$ together with its sodium salt is chosen. Acetoacetic acid is, therefore, the suitable weak acid.