What is the molar mass of a gas if 5.0 g occupies 8.2 L at 0.500 atm and 27 ° C?

Name: What is the molar mass of a gas if 5.0 g occupies 8.2 L at 0.500 atm and 27 ° C?
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Question

Quizplus · Accepted Answer

Using the ideal gas law, we can find the number of moles of the gas:
n = PV/RT = (0.500 atm)(8.2 L)/(0.08206 L·atm/mol·K)(300 K) = 0.159 mol
Then we can use the definition of molar mass:
molar mass = mass / moles = 5.0 g / 0.159 mol = 31.4 g/mol (rounded to two decimal places)
The closest answer choice is B, which is 30 g/mol.

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