Question

An evacuated glass vessel weights $50.0g$ when empty, $148.0g$ when filled with a liquid of density $0.98g/m{L}^{-1}$$and$50.5\ g$whenfilledwithanidealgasat$760\ mm\ Hg$at$300\ K$. Determine the molecular weight of the gas.

Answer 1

Mass of liquid $=148-50=98g$
Volume of liquid $=\frac{mass}{density}=\frac{98}{0.98}=100mL$
Volume of vessel = Volume of liquid
Mass of gas $50.5-50=0.5g$
On applying ideal gas equation, we have,
$PV=\frac{w}{m}RT$
$\frac{760}{760}\times \frac{100}{1000}=\frac{0.5}{m}\times 0.0821\times 300$
$m=123$