Chapter 15: Equilibrium - Introduction to equilibrium and Keq

At chemical equilibrium, the concentrations of chemical species do not change. This occurs because at equilibrium, the rate of the forward and reverse chemical reactions are equal. The relationship between reactant and product concentrations are related through the equilibrium constant, or Keq. Keq can be determined by the overall stoichiometric equations. Solids and liquids are not included in Keq, but aqueous and gas phase substances are. If pressure is used, we write Keq as Kp. If only concentrations are used, we write Keq as Kc.