Question

What is the molar mass of a gas that at `823*K` exerts a pressure of `31.89*kPa` in a volume of `56.0*mL`?

Answer 1

Approx.....`120*g*mol^-1`

Explanation:

We use the Ideal Gas equation, and solve for molar mass.....

`n=(PV)/(RT)=((31.89*kPa)/(101.3*kPa*atm^-1)xx56.0xx10^-3L)/(0.0821*(L*atm)/(K*mol)xx823*K)=2.61xx10^-4*mol`

And thus `"molar mass"="Mass of gas"/"Number of moles"`

`=(3.243xx10^-2*g)/(2.61xx10^-4*mol)=124.3*g*mol^-1`.

And note that this molar mass is consistent with a `P_4` molecule.....