1. PV = nRT Ideal Gas Law Ideal Gases Avogadro’s Principle Ideal Gas Law
Calculations
PV = nRT
Print 1-3, 5, 7, 9, 11-16

2. Ideal Gases
Ideal gases are imaginary gases that perfectly fit all of the assumptions of the kinetic molecular theory.
Gases consist of tiny particles that are far apart
relative to their size.
Collisions between gas particles and between
particles and the walls of the container are
elastic collisions (no KE is lost)

3. Ideal Gases (continued)
Gas particles are in constant, rapid motion. They
therefore possess kinetic energy, the energy of
motion
There are no forces of attraction between gas
particles
The average kinetic energy of gas particles
depends on temperature, not on the identity
of the particle.

4. Real Gases Do Not Behave Ideally
Real gases DO experience inter-molecular attractions
Real gases DO have volume
Real gases DO NOT have elastic collisions

5. Deviations from Ideal Behavior
Likely to behave nearly ideally
Gases at high temperature and low pressure
Small non-polar gas molecules
Likely not to behave ideally
Gases at low temperature and high pressure
Large, polar gas molecules

6. Avogadro's Principle
Avogadro’s principle states that equal volumes of gases at the same temperature and pressure contain equal numbers of particles.

7. Avogadro's Principle
Avogadro’s principle states that equal volumes of gases at the same temperature and pressure contain equal numbers of particles.
V1 = V2
n n2

8. Avogadro's Principle (cont.)
The molar volume of a gas is the volume 1 mol occupies at 0.00°C and 1.00 atm of pressure (STP).
At STP, 1 mol of gas occupies 22.4 L.

9. A. Ideal Gas Law Combined gas law to ideal gas law
Since n is proportional to V and P, it can be incorporated into the combined gas law.
Ideal gas constant
R = L-atm/mol-K

10. PV = nRT A. Ideal Gas Law Ideal Gas Law V = (L) n = (mol)
P = (atm)
V = (L)
n = (mol)
R = gas constant
T = (K)
( L-atm/mol-K)

11. B. Calculations
PV = nRT
A 5.00 L balloon of gas is at atm and 25oC.
How many moles of gas are in the balloon?
A balloon shrinks when submerged in cold water

12. B. Calculations
PV = nRT
A 5.00 L balloon of gas is at atm and 25oC.
How many moles of gas are in the balloon?
(0.855 atm)(5.00 L)
A balloon shrinks when submerged in cold water =
n (0.0821)(298 K)
(0.855 atm)(5.00 L)
(0.0821)(298 K) = n =
0.175 mol

13. Molar mass and The Ideal Gas Law

14. Molar mass and The Ideal Gas Law
1. A 2.00 L flask is filled with propane gas (C3H8) at a pressure of 1.00 atm and a temperature of -15.0C. What is the mass of propane in the flask?
M = mRT PV
44.11 =
m(0.0821)(258)
(1.00)(2.00)
(44.11)(1.00)(2.00)
= m =
4.16 g
(0.0821)(258)

15. Molar mass and The Ideal Gas Law
2. Determine the molar mass of an unknown gas that has a volume of mL at a temperature of 100C, a pressure of atm, and a mass of g.
M = mRT PV
= (0.424g)(0.0821)(373 K)
= g/mol
(0.980 atm)( L)

16. Quick Quiz!
1) Find the volume of a gas if 2.95 mol has a pressure of atm at a temperature of 52.0°C.
A) L
B) L
C) 104 L
D) L 16