1. Ideal Gas Law

2. Ideal Gas
Imaginary gas that conforms to all of the assumptions of the kinetic molecular theory (Day 1)

3. Real Gas
Can sometimes conform to all of the assumptions of the kinetic theory  it can behave ideally
Does not behave ideally at high pressures and/or low temperatures

4. P V = n R T Ideal Gas Law P = pressure V = Volume (L)
n = number of moles
R = ideal gas constant
T = temperature (K)

5. R: Ideal Gas Constant R = 0.0821 L atm K mol R = 62.4 L mmHg
Choose R so that the pressure units match the pressure units in the problem.

6. Example #1:
What is the pressure (in mm Hg) exerted by 85.5 g of CO2 at 27˚C if the gas is contained in a 15.0 L container?
P = ?
V = 15.0 L
n = ? (85.5 g)
R = L mm Hg
K mol
T = 27oC = 300 K

7. Example #1:
PV = nRT
P =
nRT V

8. Example #2:
What is the mass of 120 L of SO2 at a temperature of 40˚C and a pressure of 1.85 atm?
P = 1.85 atm
V = 120 L
n = ??? (but want grams)
R = L atm
K mol
T = 40oC = 313 K

9. Example #2:
PV = nRT PV RT
n =

10. We can also derive many formulas from PV=nRT to determine other values…
Molar Mass = DRT P
Molar Mass = # grams
# moles (n)
Density = P*Molar Mass RT

11. Example 3 What is the molar mass of a gas if 0
Example 3 What is the molar mass of a gas if 0.628g of the gas occupies a volume or 150 mL at 25˚C and 7456 mm Hg pressure?

12. Molar Mass = # g 0.628 g # mol Use PV=nRT to find the moles: n = PV RT