The Ideal Gas Law: Molar Mass Video Lessons

Concept: Molar Mass

# Problem: An ideal gas mixture contains 35% helium, 20% methane, and 45% nitrogen (by volume) at 2.00 atm and 90°C. Calculate the average molecular weight of the gas mixture.

###### FREE Expert Solution

With the same pressure and temperature, mole fraction and volume fraction are the same.

We can then use the molar mass of each gas and the fractions to calculate the average molar mass:

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###### Problem Details

An ideal gas mixture contains 35% helium, 20% methane, and 45% nitrogen (by volume) at 2.00 atm and 90°C. Calculate the average molecular weight of the gas mixture.