1. Topic: Gay-Lussac’s Law
Do Now:

2. Gay-Lussac (1778-1850) was a balloonist 1802: climbed to 23,000 feet
record stood for 50 years
investigated composition of atmosphere as function of altitude

3. Gay-Lussac
Examined relationship between P & T at constant V and # moles
As T :
gas molecules move faster, collide with walls more frequently & more energetically
Pressure results from collisions between gas molecules & walls of container
So, if T , expect P

4. Based on the last slide, explain in your own words why a balloon expands when the temperature is increase

5. Which temperature scale has a direct relationship to molecular velocity?
Kelvin

6. (K) Typical data from a Gay-Lussac type experiment
What kind of relationship is illustrated in this graph?
(K)

8. Gay-Lussac’s Law Relationship between P & T
at constant volume & # moles
P = kT or P/T = k
It’s direct relationship
Straight line with y-intercept of zero

9. Gay-Lussac’s Law: words
pressure exerted by confined gas is directly related to Kelvin temperature at constant volume & # moles

10. REMEMBER ALL TEMPERATURE MUST BE CONVERTED TO KELVIN
Gay-Lussac’s Law
P1 = P2
T T2
REMEMBER ALL TEMPERATURE MUST BE CONVERTED TO KELVIN

11. When temperature decreases, the pressure of a gas _____________
(decreases, increases, stays the same)
When temperature increases, the pressure of a gas ___________
Decreases
Increases