1. Ch. 13/14
Gas Laws

2. Key Vocabulary
Kinetic Energy: the energy that molecules have by being in motion
Kinetic Theory of Gases: Gas molecules' kinetic energy is random, constant, and perfectly elastic as they collide with each other and the walls of its container.

3. Example: Water molecules in 3 different states
Turn and Talk
- Do molecules of a substance ever stop moving, regardless of whether it is in a solid, liquid, or gaseous state? Why or why not?

4. Boyle's, Charles, and Gay-Lussacs Law
Review from the Web Quest: The effects of changing temp., pressure, and volume of a gas can be described as the following laws
Boyle's Law ---- P1V1 = P2V2
Charles' Law ---- V1/T1 = V2/T2
Gay-Lussac's Law ---- P1/T1 = P2/T2
***There is a very very easy way to remember all 3!
P1V P2V2
  T1          T2
The Combined Gas Law

5. Using the combined gas law
P1V P2V2
  T1          T2
The prefix iso means “same”
Isothermal = same temperature P1V1 = P2V2
Remove the T from the combined gas law
Isobaric = same pressure V1/T1 = V2/T2
Remove the P from the combined gas law
Isovolumetric = same volume P1/T1 = P2/T2
Remove the V from the combined gas law
If not isothermal, isobaric, or isometric, we can still use the combined gas law.

6. Learning check
P1V P2V2
  T1          T2
Given: an isothermal situation P1 = 2atm V1 = 35L
solve for V P2 = 5atm V2 = ?
2atm x 35L = 5atm x V V2 = 14 L
Given: P1 = 3 atm V1 = 8.5 L T1 = 95°C
P2 = 5atm V2 = 7L T2 = ?
(3atm x 8.5 L) / K = (5atm x 7L) / T2
T2 = K
NOTE: When using gas laws always use K for temperature.
K = °C