Calculate the molar mass of this unknown liquid?

Question

In the Dumas-bulb technique for determining the molar mass of an unknown liquid, you vaporize the sample of a liquid that boils below 100°C in a boiling-water bath and determine the mass of vapor required to fill the bulb. From the following data, calculate the molar mass of the unknown liquid: mass of unknown vapor, 1.413 g; volume of bulb, 481 cm3; pressure, 742 torr; temperature, 99°C.

Answer 1

Rearrange the Ideal Gas Law:

PV = (g/MM)RT
MM = gRT/PV

Convert temperature to Kelvin (C + 273), pressure to atmospheres (torr/760), volume to liters (cm3/1000) and use R = 0.08206.