AS and A2 Chemistry notes and resources (WJEC specification) - UNIT CH5 Physical and inorganic chemistry

This unit develops ideas of redox, kinetics, energy changes and equilibria. The inorganic chemistry of some elements in various sections of the Periodic Table is studied.

20.1 - General Equilibria

Candidates should be able to:

(a) deduce expressions for the equilibrium constants, Kp and Kc in terms of partial pressures or of concentrations, as appropriate;

(b) appreciate that Kp or Kc are constant for a given system at any fixed temperature and understand the effect of temperature changes on Kp or Kc for exothermic and endothermic reactions;

(c) calculate values of Kp and Kc or of quantities present at equilibrium, given appropriate data (no manipulations of mole fraction or of degree of dissociation will be required);

(d) show ability to use given or calculated values of Kp and Kc to estimate qualitatively the location of the position of equilibrium for a system;

(e) recognise that for a reaction with G negative (see 19.2 (h)) Kp and Kc will have large values as the products predominate and that for a reaction with G positive Kp and Kc will have small values as the reactants predominate;

(f) appreciate the distinction between what may be deduced from equilibrium data and what may be deduced from kinetic data; (g) integrate and evaluate supplied kinetics, energetics and equilibria data for environmental and industrial chemical processes.