2-Variable Gas Laws

Kinetic-Molecular

Theory1. Gas particles do not attract or repel each other

2. Gas particles are much smaller than the distances between them

3. Gas particles are in constant, random motion

Kinetic-Molecular

Theory

5. All gases have the same average kinetic energy at a given temperature

4. No kinetic energy is lost when gas particles collide with each other or with the walls of their container

Boyle’s LawVolume and pressure are inversely related in gases at a constant temperature.

P1V1 = P2V2

Boyle’s Law PracticeA sample of helium gas in a

balloon is compressed from 4.0 L to 2.5 L at a constant temperature. If the pressure of the gas in the 4.0 L volume is 210 kPa, what will the pressure be at 2.5 L?

Temperature ConversionSince temperature relates

directly to the kinetic energy of a sample, we must use an absolute scale when doing gas law calculations.

Always convert to Kelvins before solving gas law calculations.

K = °C + 273

Charles’s LawVolume and temperature (K) of a gas are directly proportional at constant pressure.

V1 = V2

T1 T2

Charles’s Law PracticeA gas sample at 40.0℃ occupies a

volume of 2.32 L. If the temperature is raised to 75℃, what will the volume be, assuming the pressure remains constant?

Gay-Lussac’s LawPressure is directly

proportional to the temperature (K) of a gas when volume is constant

P1 = P2

T1 T2

Gay-Lussac’s Law PracticeThe pressure of a gas in a tank is

3.20 atm at 22.0 ℃. If the pressure falls to 1.55 atm, what will be the Celsius temperature of the gas in the tank?