Question #b7884

1 Answer
Jan 28, 2015

The relative molecular mass of the gas is 39.2 g/mol.

A very important thing happens at STP with ideal gases: 1 mole of any ideal gas occupies 22.4 L - the molar volume of a gas. Since density is defined as mass per unit volume, you can automatically find the mass of 1 mole of gas (notice that I've converted 1 L to 1 dm3)

ρ=mVm=ρVmolar=1.750 g/dm322.4 dm3

m=39.2 g

Therefore, the gas' molar mass is

molar mass=39.2 g1 mole=39.2 g/mol

This is pretty close to Ar's molar mass, so that could be the identity of the gas.