An evacuated glass vessel weighs `50.0 g` when empty, `148.0 g` when filled with a liquid of density `0.98 g mL^(-1)`, and `50.5 g` when filled with an ideal gas at `760 mm Hg` at `300 K`. Determine the molar mass of the gas.

Explanation

Mass of ideal gas `=50.5-50=0.5 g`
Mass of liquid `=148-50=98 g`
`Volume=(Mass)/(Density)=(98)/(0.98)=100 mL` or `0.1 L`
For the gas,
`PV=(w)/(M)RT`
or `(760)/(760)xx0.1=(0.5)/(M)xx0.0821xx300`
or `M=123.15`