Topic: Gay-Lussac’s Law Do Now:

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

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

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

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

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

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

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

REMEMBER ALL TEMPERATURE MUST BE CONVERTED TO KELVIN Gay-Lussac’s Law P1 = P2 T1 T2 REMEMBER ALL TEMPERATURE MUST BE CONVERTED TO KELVIN

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