The Kinetic Theory of Gases
Gases consist of particles in constant, random motion. The kinetic theory assumes: (1) gas particles have negligible volume compared to the container; (2) no intermolecular forces exist between particles; (3) collisions are perfectly elastic. These assumptions define an ideal gas. Real gases deviate under high pressure or low temperature.
Boyle's Law
Charles's Law
Ideal Gas Law
Summary of Gas Laws
The three classical gas laws and the combined ideal gas law.
| Law | Relationship | Constant | Equation |
|---|---|---|---|
| Boyle's | P ∝ 1/V | T, n | P₁V₁ = P₂V₂ |
| Charles's | V ∝ T | P, n | V₁/T₁ = V₂/T₂ |
| Gay-Lussac's | P ∝ T | V, n | P₁/T₁ = P₂/T₂ |
| Avogadro's | V ∝ n | T, P | V₁/n₁ = V₂/n₂ |
| Ideal Gas | PV = nRT | — | PV = nRT |
HSC Exam Focus
Always convert temperature to Kelvin (K = °C + 273.15) before substituting into any gas law. Common mistakes: using °C directly, forgetting to check which variables are held constant. At STP (0 °C, 1 atm), 1 mole of ideal gas occupies 22.4 L.
Biochemistry Bridge
Gas laws govern oxygen delivery in the blood. In high-altitude regions (low P), dissolved O₂ in plasma decreases (Henry's Law). The body responds by producing more red blood cells — a direct application of PV = nRT in physiology.
InstaTest
InstaTest: Gas Laws
Test your understanding of Boyle's, Charles's, and the ideal gas law.