Question

An evacuated glass vessel weighs $50.0$g when empty, $148.0$ gm when filled with a liquid of density $0.98$ g/mL and $50.5$ g when filled with an ideal gas at $760$ mm Hg at $300$k. Determine the molecular weight of the gas?

Answer 1

Weight of Liquid $=148-50=98g$

Volume of liquid $=\frac{98}{0.98}=100mL=$Volume of vessel

Thus a vessel of $100mL$ contains ideal gas at $760mm$of $Hg$ at $300K$

Weight of gas $=50.5-50=0.5g$

Using $PV=nRT$

$\frac{760}{760}\times \frac{100}{1000}=\frac{0.5}{m}\times 0.0821\times 300$

Since,

Molecular weight of gas $\left(m\right)=123$