CHEMICAL EQUILIBRIUM
Outline
1. Introduction
2. Reversible reactions
3. Equilibrium Constants
4. Homogeneous Equilibria
5. Heterogeneous Equilibria
6. Free Energy and Chemical Equilibrium
7. Factors that affect Chemical Equilibrium
a) Concentration. Pressure. Volume: Le Châtelier’s Principle
b) Variation of K with temperature: The Clausius-Clapeyron Equation
1. Introduction
The concentration of reactants and products remains constant with time. No macroscopic changes are observed.
Equilibrium – two opposing processes taking place at equal rates.
2. Reversible reactions
Forward: CO(g) + 2 H2(g) → CH3OH(g) R(fwrd) = k(1)[CO][H2]^2
Reverse: CH3OH(g) → CO(g) + 2 H2(g) R(rvrs) = k(-1)[CH3OH]
At Equilibrium:
Rfwrd = Rrvrs CO(g) + 2 H2(g) ↔ CH3OH(g)
k1[CO][H2]^2 = k-1[CH3OH]
3. Equilibrium constants
aA +bB ⇔ cC+dD
When K >> 1 Products are favoured
When K << 1 Reactants are favoured