Applications of the Ideal Gas Law
Density of a Gas
Example 1: Nitrogen gas is the most abundant gas in the atmosphere.
What is the density of nitrogen gas, in g/L at 12.5oC and
126.63kPa?
Solution:
T = 285.5K
P = 126.63kPa
V = 1 (We can assume the volume is 1 since amount is not given)
1. Solve for moles:
2. Solve for mass
3. Calculate density
PV = nRT
Example 2: Oxygen is the second most abundant gas in the
atmosphere. Calculate the density of oxygen at STP.
We could make assumptions and follow the procedure above or we
can use a little math help.
Density = mass
or
Volume
Proof:
Molar Volume
Molar Mass
g/mol
Molar volume
L/mol
g . = mol
mol
Solution:
D=?
MM =
MV =
Density = Molar Mass
L