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 "dm"^3)

rho = m/V => m = rho * V_("molar") = "1.750 g/dm"^3 * "22.4 dm"^3

m = "39.2 g"

Therefore, the gas' molar mass is

"molar mass" = ("39.2 g")/("1 mole") = "39.2 g/mol"

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