If 28.0 g of methane gas (CH_4) are introduced into an evacuated 2.00-L gas cylinder at a temperature of 35°C, what is the pressure inside the cylinder?

1 Answer
Feb 22, 2016

The pressure of the methane gas will be 22.2 atm.

Explanation:

Use the ideal gas law with the formula PV=nRT, where n is moles, R is the gas constant, and T is temperature in Kelvins.

Determine the mole of "CH"_4" by dividing the given mass by its molar mass, "16.04246 g/mol" https://pubchem.ncbi.nlm.nih.gov/compound/297

28.0cancel"g CH"_4xx(1"mol CH"_4)/(16.04246cancel"g CH"_4)="1.7454 mol CH"_4"

Ideal Gas Law

Given/Known
V="2.00 L"
n="1.7454 mol"
R="0.082057338 L atm K"^(-1) "mol"^(-1)
T="35"^@"C"+273.15="308 K"

Unknown
Pressure, P

Solution
Rearrange the formula to isolate P. Substitute the given values into the formula and solve.

PV=nRT

P=(nRT)/V

P=((1.7454"mol") xx (0.082057338"L atm K"^(-1) "mol"^(-1)) xx (308"K"))/(2.00"L")="22.2 atm" rounded to three significant figures