Dynamic equilibrium, le Chatelier’s principle and Kc

dynamic equilibrium

exists in a closed system when the rate of forwards reaction is equal to the rate of the backwards reaction, concentrations of the products and reactants remain constant.

le Chatelier’s principle

if dynamic equilibrium is disrupted, equilibrium will shift to oppose the change. If pressure is increased(volume decreased), then equilibrium will shift to the side with less moles of gas and v.v. If temperature is increased, then equilibrium will shift to the endothermic side to produce more moles of the endothermic situation and v.v. If concentration of reactants is increased, equilibrium will shift to the product to produce more products and v.v. (for reactions in solution)

Catalyst…

increases the rate of forward and backwards reactions equally by providing an alternate pathway that requires less activation energy, without getting used up itself. Does not change the position of equilibrium.

haber process

synthesis of ammonia
N­₂ (g) + 3H₂ (g) ⇌ 2NH₃ (g)
400-450 ^oC
200 atm
iron catalyst

contact process

synthesis of sulphuric acid
2SO­₂ (g) + O₂ (g) ⇌ 2SO₃
1 atm- because Kp for this reaction is already very high so position of the equilibrium is already far over to the right.
450 ^oC
vanadium(V) oxide catalyst

homogeneous reaction

all reactants and products are the same states

when Kc is>1 then equilibrium shifts to

Kc<1

Kc=1

RHS

LHS

reaction @ equilibrium