Problem: An experiment shows that a 248 -mL gas sample has a mass of 0.434 g at a pressure of 747 mm Hg and a temperature of 28 oC.What is the molar mass of the gas?

FREE Expert Solution

We’re being asked to determine the molecular weight of the unknown gas. 

Recall that molecular weight is in grams per 1 mole of a substance.

Molecular Weight (MW)=gmol


Step1: First, we have to calculate the amount of gas in moles using the ideal gas equation.

PV=nRT

P = pressure, atm
V = volume, L
n = moles, mol
R = gas constant = 0.08206 (L·atm)/(mol·K)
T = temperature, K


Isolate n (number of moles of gas): 

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Problem Details

An experiment shows that a 248 -mL gas sample has a mass of 0.434 g at a pressure of 747 mm Hg and a temperature of 28 oC.

What is the molar mass of the gas?

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What scientific concept do you need to know in order to solve this problem?

Our tutors have indicated that to solve this problem you will need to apply the Ideal Gas Law Molar Mass concept. If you need more Ideal Gas Law Molar Mass practice, you can also practice Ideal Gas Law Molar Mass practice problems.