1. The Combined Gas Law and the Ideal Gas Law
Sections 2
The Combined Gas Law and the Ideal Gas Law

2. Objectives
State the relationship among temperature, volume, and pressure as the combined gas law.
Apply the combined gas law to problems involving the pressure, temperature, and volume of a gas
Relate the amount of gas present to its pressure, temperature, and volume by using ideal gas law
Apply the ideal gas law to problem solving

3. Key Terms
Combined gas law
Ideal gas constant, R
Ideal gas law
Avogadro’s principle
Molar volume

4. The Combined Gas Law
P1V1 = P2V2
T T2

5. Practice Problem
A balloon has a volume of 2.1 L at atm and 36 ºC. Upon being released, the pressure drops to atm and 28 ºC. What is the new volume?

6. Avogadro’s Principle
Moles are proportionate to V, at constant T and P.

7. Ideal Gas Law:
Combines Boyle, Charles, Gay-Lussac, Avogadro
PV = nRT

8. PV=nRT
P  atm
V  L
n  mols
R  L-atm/mol-K
T  Kelvin

9. Practice Problem
If the pressure exerted by a gas at 25 °C in volume of L is 1950 torr, how many moles of gas are there?

10. When given grams…
Convert grams to mols
Use the mol value for n

11. When solving for grams
Solve for n (mols)
Convert mol to grams

12. Practice Problem
Calculate the grams of nitrogen present in a L sample at 1.00 atm and 22.0 ºC.

13. Homework
Combined and Ideal Gas Law Worksheet