Gas Laws

Boyle's Law — At constant temperature, pressure and volume are inversely related.

Boyle's Law

Set the temperature first, then move the piston. Temperature stays constant while you compress or expand the gas.

Controlled variable: Temperature K

The gas's temperature is kept constant by contact with a large external heat reservoir.

Manipulated variable: Volume L

See how pressure (the dependent variable) changes as volume (the manipulated variable) changes.

Number of particles

Gas compression experiment

Formulated by Robert Boyle in 1662.

Gas in pistonP = 1.05 atm
Pressure-volume graph

The orange point is the current state. Moving the piston shifts it along the curve.

Charles's Law

Set the pressure first, then change the temperature. Pressure stays constant while the volume responds.

Controlled variable: Pressure atm

The gas's pressure is kept constant by a fixed weight resting on the piston.

Manipulated variable: Temperature K

See how volume (the dependent variable) changes as temperature (the manipulated variable) changes.

Number of particles

Gas expansion experiment

Discovered by Jacques Charles around 1787.

Gas in pistonV = 3.50 L
Volume-temperature graph

The orange point is the current state. Moving the temperature shifts it along the line.

Gay-Lussac's Law

Set the volume first, then change the temperature. Volume stays constant while the pressure responds.

Controlled variable: Volume L

The gas's volume is kept constant by pins that fix the piston in place.

Manipulated variable: Temperature K

See how pressure (the dependent variable) changes as temperature (the manipulated variable) changes.

Number of particles

Gas heating experiment

Discovered by Guillaume Amontons around 1702.

Gas in pistonP = 1.05 atm
Pressure-temperature graph

The orange point is the current state. Moving the temperature shifts it along the line.