A buffer solution is prepared by mixing equimolar acetic acid and sodium acetate. If ' $\mathrm{K}_{\mathrm{a}}$ ' of acetic acid is $1.78 imes 10^{-5}$, find the $\mathrm{pH}$ of buffer solution.

Question

A buffer solution is prepared by mixing equimolar acetic acid and sodium acetate. If ' $\mathrm{K}_{\mathrm{a}}$ ' of acetic acid is $1.78 	imes 10^{-5}$, find the $\mathrm{pH}$ of buffer solution.

Aicharya · Accepted Answer

For acidic buffer, $\begin{aligned} \mathrm{pH} & =\mathrm{pK}_{\mathrm{a}}+\log _{10} \frac{[	ext { Salt }]}{[	ext { Acid }]}=\mathrm{pK}_{\mathrm{a}}+\log _{10} \frac{1}{1}=\mathrm{pK}_{\mathrm{a}} \ \mathrm{pK}_{\mathrm{a}} & =-\log _{10} \mathrm{~K}_{\mathrm{a}}=-\log _{10}\left(1.78 	imes 10^{-5}ight) \ & =-\left(\log _{10} 1.78+\log _{10} 10^{-5}ight) \ & =-(0.25-5)=4.75 \end{aligned}$ Therefore, $\mathrm{pH}$ of buffer solution $=4.75$

A buffer solution is prepared by mixing equimolar acetic acid and sodium acetate. If '…

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