A2 AQA CHEM4 3.4.2

3.4.2 Equilibria

Equilibrium constant K_c for homogenous systems

·         Dynamic equilibriumà the concentration of products and reactants remains constant and the forward rate of reaction is equal to the backward rate of reaction

·         Le Chatalierà if the conditions of a reaction at equilibrium are changed, the position of the equilibrium will shift to minimise/oppose the effect of the change

·         Increase in pressure= shift to side with fewer moles

·         Increase in temperature= shift to endothermic side

·         Increase in concentration on one side= shift to the other side

·         Catalysts= change the forward rate of reaction by the same amount as the backward rate of reaction so the position of the equilibrium doesn’t change

K_c

·         Quantitative description of the position of equilibrium at a constant temperature

·         aA + bB <-->  cC + dD

o   K_c= [C]^c[D]^d / [A]^a[B]^b

o   So remember the products go on the top

o   The units of K_c…