Chemical Equilibria
Chemical Equilibria — Edexcel International A-Level Chemistry (Unit 4). Quantitative Kc and Kp: equilibrium-constant expressions, ICE-table calculations, units, the effect of temperature on K (exo vs endo via ΔS_total = R ln K), invariance under concentration/pressure/catalyst, and using the magnitude of K to predict the extent of reaction.
The Equilibrium Constant KcSign up
Writing the Kc expression for any homogeneous equilibrium · Setting up ICE tables (Initial / Change / Equilibrium) to compute Kc from experimental data · Deriving the units of Kc from Δn and the invariance of Kc under concentration / pressure / catalyst changes
Kp for Gas-Phase EquilibriaSign up
Mole fractions and partial pressures: p_i = x_i × P_total · Building the Kp expression, calculating Kp from equilibrium moles + total pressure, and deriving the units (atm)^Δn
Factors Affecting K and Predicting ExtentSign up
K depends only on T: concentration, pressure, volume, and catalyst all leave K unchanged · Temperature effect on K for exothermic vs endothermic reactions, linked to ΔS_total = R ln K · Using the magnitude of K (K >> 1, K ≈ 1, K << 1) to predict the extent of reaction