Kinetic Theory.

13 lessons100 min5 simulations10 practice questions

This chapter explains the behaviour of a gas from the motion of its molecules. It first fixes the scales (atoms about 1 Å, spacing in a gas tens of Å, mean free path thousands of Å) and the ideal-gas equation PV = μRT = k_BNT, with Boyle's, Charles' and Dalton's laws as special cases. Treating the molecules as tiny elastic balls hitting the walls gives P = ⅓nm⟨v²⟩; set beside the gas equation it says the average kinetic energy of a molecule is (3/2)k_BT, so temperature measures molecular motion and v_rms = √(3k_BT/m). Equipartition, ½k_BT for every squared term in the energy, then predicts the specific heats of monatomic, diatomic and polyatomic gases and 3R for solids. The chapter ends with the mean free path, which explains why gases mix slowly although their molecules are fast.

Also called: kinetic theory of gases · KTG · ideal gas