$\mathrm{K}_{\mathrm{a}}$ for butyric acid $\left(\mathrm{C}_{3} \mathrm{H}_{7} \mathrm{COOH}\right)$ is $2 \times 10^{-5}$. The $\mathrm{pH}$ of $0.2 \,\mathrm{M}$ solution of butyric acid is __________ $\times 10^{-1}$. (Nearest integer)
[Given $\log 2=0.30$]
Answer (integer)
27
Solution
$\mathrm{K}_{\mathrm{a}}$ of Butyric acid $\Rightarrow 2 \times 10^{-5} \,\mathrm{PKa}=4.7$ <br/><br/>$\mathrm{pH}$ of $0.2 \mathrm{M}$ solution,<br/><br/>
$\mathrm{pH}=\frac{1}{2} \mathrm{pK}_{\mathrm{a}}-\frac{1}{2} \log \mathrm{C}$<br/><br/>
$$
\begin{aligned}
&=\frac{1}{2}(4 \cdot 7) - \frac{1}{2} \log (0.2) \\\\
&=2.35+0.35=2.7
\end{aligned}
$$<br/><br/>
$\mathrm{pH}=27 \times 10^{-1}$
About this question
Subject: Chemistry · Chapter: Equilibrium · Topic: Chemical Equilibrium and Kc, Kp
This question is part of PrepWiser's free JEE Main question bank. 67 more solved questions on Equilibrium are available — start with the harder ones if your accuracy is >70%.