What is the molar mass of a gas if a 40.0-gram sample of the gas occupies 11.2 liters of space at STP?

1 Answer
Mar 11, 2016

M=80.0gmol

Explanation:

For this solution one would use the variation of the Ideal Gas Law
PM=dRT
P=Pressure in atm
M=MolarMass in gmol
d=Density in gL
R=0.0821atmLmolK the gas law constant
T=Temperature K

The density can be found by dividing the mass by the volume.

d=massvolume=gL

mass=40.0g
volume=11.2L

d=40.0g11.2L
d=3.57gL

The STP values (standard temperature and pressure) are 1 atm and 273 K.

P=1atm
M=?
d=3.57gL
R=0.0821atmLmolK
T=273K

PM=dRT
(1atm)(M)=(3.57gL)(0.0821atmLmolK)(273K)
(M)=(3.57gL)(0.0821atmLmolK(273K))1atm
M=80.0gmol