Question

A polythene bag of $3$ litre capacity is filled by Helium gas (occupying $Li$ at $0.3atm$ and $300K$) at $300K$. Subsequently enough $Ne$ gas is filled to make total pressure $0.4atm$ at $300K$. Calculate ratio of moles of $Ne$ to $He$ in container.

Answer 1

$x_{He}=\frac{p_{He}}{p_{He}+p_{Ne}}=\frac{0.3}{0.3+0.1}=\frac{3}{4}$

$x_{Ne}=\frac{0.1}{0.1+0.3}=\frac{1}{4}$

now, $\frac{n_{Ne}}{n_{He}}=\frac{x_{Ne}}{x_{He}}=\frac{1}{3}$