Dynamic Equilibrium

What does rate of condensation equal to

Rate of evaporation

means system reached eq.

What remains constant at eq

concentrations

• eq. reached

Why is it dynamic - chemical

Forwards and backwards reactions still occuring

Left to right

• reactant to product

• forward reaction

Right to left

• Product to reactant

• backwards reaction

Lies to left

more reactant

Lies to right

more product

Equilibrium constant expression

High value of K

more products than reactants

• right

• goes near completion

Low value of K

More reactants than products

• left

• barely taken place

reverse reaction

Backwards reaction

K’ or K-1

Le Châteliers principle

A system at equilibrium when subjected to a change will respond in such a way to minimise the effect of change

Changes in pressure

• increase in P, favours side with smaller number of molecules

• different eq. position, K stays the same

Changes in temperature

• will change K, K depends on temp

• Exothermic - releases energy (H negative)

• endothermic - absorbs energy (h positive)

• Increasing temp - increase K for endothermic

• increasing temp - decrease K for exothermic

Adding catalyst

• Lowers activation energy

  • speeds up achieving eq.

• No effect on eq. position or K value

• Used in industry

Summary - factors

Production of ammonia

N2 + 3H2 = 2NH3