Question

$pH$ of $0.1M$ monobasic acid is measured to be $2$. Its osmotic pressure at a given temperature $TK$ is:

• A. $0.1RT$
• B. $0.11RT$
• C. $1.1RT$
• D. $0.01RT$

Answer 1

The correct option is B $0.11RT$

Given, $pH=2$
$\therefore pH=-log\left[H^{+}\right]So,H^{+}={10}^{-2}\therefore C=\frac{H^{+}}{\alpha }\alpha =\frac{{10}^{-2}}{0.1}=0.1$
Now $\alpha =\frac{i-1}{0.1}=\frac{i-1}{2-1}\text{(For monobasic acid (n) = 2})$
$\Rightarrow 0.1=i-1\Rightarrow i=1.1\text{Osmotic pressure}\left(\pi \right)=i.CRT=1.1\times 0.1\times RT=0.11RT$
Therefore, the correct option is (B)