What is the molar mass of the gas?

Question

A 40.80 gram sample of a gas in a rigid container is at 777.7 torr and 223.1 K. What is the molar mass of the gas?

Answer 1

PV = nRT

since n = m/M, moles = mass / molar mass

then

PV = mRT / M

Solve for M

M = mRT / PV = 40.80g x 62.4 Ltorr/molK x 223.1K / 777.7 torr / V

As soon as you get the volume, you can finish the calculation.

Answer 2

I don't think you can get the answer unless you have the volume of the rigid container.

PV = nRT

you have the Temp, and Pressure so you could calculate the moles/Volume but without the volume I don't think you can calculate the molar mass.