IDEAL GAS LAW
IDEAL GAS
• Follows all gas laws under all conditions of
temperature and pressure
• Follows all conditions of the Kinetic Molecular Theory
(KMT)
• An ideal gas does not exist in real life
REAL GAS
• Follows some gas laws under some conditions of
temperature and pressure
• Does not conform to the Kinetic Molecular Theory.
Real gases have a volume and attractive and
repulsive forces
• A real gas differs from an ideal gas the most at low
temperature and high pressure
IDEAL GAS LAW EQUATION
PV = nRT
P= pressure (atm, torr, mmHg, kPa)
V= volume (L, mL)
n = # of moles (mol)
R = Ideal Gas Constant
T = temperature in Kelvin (K, ˚C +273)
IDEAL GAS CONSTANT
R = 0.0821L atm = 8.314 L kPa = 62.4 L mmHg = 62.4 L torr
mol K
mol K
mol K
mol K
* Use the same unit as your given pressure
EXAMPLE 1
Calculate the number of moles of gas contained in a
3.00L vessel at 298K with a pressure of 1.50 atm.
V = 3.00L
T = 298K
P = 1.50atm
n=?
R = 0.0821 L atm
mol K
PV=nRT
(1.50)(3.00) = n (0.0821) (298)
n= 0.184 mol
EXAMPLE 2
What will the pressure (in kPa) be when there are
0.400 mol of gas in a 5.00L container at 17.0˚C?
V = 5.00L
T = 17.0˚C = 290K
P = ? kPa
n = 0.400 mol
R = 8.314 L atm
mol K
PV=nRT
P(5.00) = (0.400)(8.314) (290)
P= 193 kPa