Gay-Lussac's Law states that pressure and temperature are directly related for a gas at constant volume: if temperature increases, pressure increases; if temperature decreases, pressure decreases. This is because temperature affects the kinetic energy of gas particles - higher temperature means more kinetic energy and more frequent and energetic particle collisions, resulting in higher pressure. The law can be expressed as P1/T1 = P2/T2, allowing calculations of pressure changes with temperature changes when volume is held constant and temperatures are in Kelvin.

1. Gay-Lussac’s Law
Temperature-Pressure
relationships

2. Pressure and temperature are directly related
 If temperature increases, pressure increases
 If temperature decreases, pressure decreases.
 Why?
 Temperature affects kinetic energy
 More kinetic energy= more collisions = more
pressure
 Animation

3. P1/T1 = P2/T2
 Volume must be held constant
 Temp. must be in Kelvin
 A balloon at 293 K and 1 atm is heated to 324K.
What is the pressure inside the balloon?
 A can has a pressure of 2.5 atm at 36oC. If we cooled
the can to 100 C what would be the new pressure?