Learn the Gas Laws
The gas laws describe how pressure, volume, temperature and amount of gas are related. Each law isolates a subset of these variables. Master the individual laws and the Ideal Gas Law ties them together.
Ideal Gas Law
The master equation. Relates pressure, volume, moles and temperature through the gas constant R. Derives from the kinetic molecular theory.
Combined Gas Law
Unifies Boyle's, Charles's and Gay-Lussac's laws. Use when all three variables can change.
Boyle's Law
At constant temperature, pressure and volume are inversely proportional. Compress a gas, pressure rises. Robert Boyle, 1662.
Charles's Law
At constant pressure, volume is directly proportional to absolute temperature. Jacques Charles, 1787.
Gay-Lussac's Law
At constant volume, pressure is directly proportional to absolute temperature. Explains why aerosol cans warn against heat.
Avogadro's Law
Equal volumes of gases at the same T and P contain equal numbers of molecules. One mole = 22.414 L at STP.
Dalton's Law
Total pressure of a gas mixture equals the sum of partial pressures. Air is 78% N₂, 21% O₂, 1% Ar.
van der Waals Equation
Corrects the Ideal Gas Law for real gas behavior. Accounts for molecular size (b) and attraction (a).