States of Matter 1 Question 27
27. Equal weights of ethane and hydrogen are mixed in an empty container at $25^{\circ} \mathrm{C}$. The fraction of the total pressure exerted by hydrogen is
$(1993,1 \mathrm{M})$
(a) $1: 2$
(b) $1: 1$
(c) $1: 16$
(d) $15: 16$
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Solution:
- Let $x \mathrm{~g}$ of each gas is mixed.
$$ \begin{aligned} \text { Mole of ethane } & =\frac{x}{30} \ \text { Mole of hydrogen } & =\frac{x}{2} \end{aligned} $$
Mole fraction of hydrogen $=\frac{\frac{x}{2}}{\frac{x}{2}+\frac{x}{30}}=\frac{15}{16}$
$$ \Rightarrow \quad \frac{\text { Partial pressure of } \mathrm{H}_{2}}{\text { Total pressure }}=\text { Mole fraction of hydrogen } $$
