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
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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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Our tutors have indicated that to solve this problem you will need to apply the The Ideal Gas Law: Molar Mass concept. You can view video lessons to learn The Ideal Gas Law: Molar Mass Or if you need more The Ideal Gas Law: Molar Mass practice, you can also practice The Ideal Gas Law: Molar Mass practice problems .

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