Question

Ratio of Henry’s constant, $K_H$ of two inert gases A $\&$ B is 2 at a given temperature. A mixture containing 4 moles of gas A and 8 moles of gas B is bubbled through water covered from top and solution is allowed to attain equilibrium. Assuming the absence of any other gases, what will be the ratio of mole fractions of gases in the solution.

• A. 1:1
• B. 8:9
• C. 7:8
• D. 1:2

Answer 1

The correct option is B 8:9

Let ‘a’ and ‘b’ moles of gases dissolve in water while rest accumulates over the solution to create partial pressure.

From Henry’s Law –

$p=K_{H}X$

$\Rightarrow \frac{p_1}{P_2}=\frac{K_{H1}}{K_{H2}}\times \frac{X_1}{X_2}$

$\Rightarrow \frac{4-a}{8-b}=\frac{1}{2}\times \frac{a}{b}$

$\Rightarrow \frac{4-a/b}{8-1}=\frac{1}{2}\times \frac{a}{b}$

$\Rightarrow \frac{a}{b}=\frac{4\times 2}{9}=\frac{8}{9}$

Hence Answer is option (b)