A dry gas measuring 280 ml at 305 K and 750 mm of Hg, weighs 0.344 g. Calculate the molecular weight of the gas.

Explanation

Accordint to ideal gas equation,
`PV=w/M RT`
P=Pressure `=(750)/(760)=0.987atm`
V=Volume `=(280)/(1000)=0.28L`
We know that `n=w/M=("mass of gas")/("Molecular mass")`
w=0.334 g
R=Gas constant =0.0821 L atm/K/mol
T=Absolute temperature =305K
Substitute :
`0.987 xx 0.28=(0.344)/(M) (0.0821 xx 305)`
`M=(1.246) (25.04)`
M=31.17