1. The General Gas Equation Combined Gas Law
P1V1
n1T1 =
P2V2
n2T2

2. Ideal Gas Equation

3. Combining the Gas Laws: The Ideal Gas Equation is derived using the Ideal Gas ConstantP
Boyle’s law V  1/P
Charles’s law V  T
Avogadro’s law V  n nT
Any gas whose behavior conforms to the ideal gas equation is called an ideal or perfect gas.
R is the gas constant. Substitute and calculate.
V = R P
PV = nRT

4. The Gas Constant PV = nRT PV R = nT = 0.08206 L atm/mol K
= L psi / mol K
= Pa m3 / mol K
= J/mol K
= L Torr/ mol K

5. The General Gas Equation
P1V1
n1T1 =
P2V2
n2T2
R =

6. Example
A 5.0 L cylinder contains oxygen gas at 20.0°C and 735 mm Hg. How many grams of oxygen are in the cylinder?
Catalog Variables
P = 735 mmHg
V = 5.0 L
n = # moles O2
R = L atm / mol K
T = 20 °C

7. Example P = 735 mmHg 1 atm = 0.967 atm 760 mmHg Convert Units
V = 5.0 L
n = # moles O2
R = L atm / mol K
T = 20 °C = 293 K
0.201 mol O2
32.0 g O2
= g O2
1 mol O2
Solve Equation
= mol O2

8. Molar Mass Determination
and
n = m MM
PV = nRT
PV = m MM RT m RT m RT
MM =
MM = PV PV
P MM
dRT
d =
MM = RT P