Question

A container of volume V = 103 cm3 has a mass of 30.0042 g when evacuated. When the container is filed with an unknown gas of pressure p = 4.72 atm at temperature T = 20oC, the mass of the system increases to 30.9508 g. Assuming that the unknown gas behaves like an ideal gas, calculate from these data the average molar mass of the unknown gas.