Molar mass from gas density
A gas has a density of 1.25 g/L at STP, where one mole occupies 22.4 L. What is its molar mass?
Answer C: explanation for every choice
A
This divides density by 22.4 instead of multiplying.
B
This is half the correct value.
C
Correct. M = density × molar volume = 1.25 g/L × 22.4 L/mol = 28 g/mol, consistent with N2 or CO.
D
This is double the correct value.
TakeawayAt STP: molar mass = density × 22.4 L/mol.
Equation usedIdeal gas law
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