Equilibrium (OCR GCSE Chemistry A, Combined (Gateway Science Suite)): Revision Notes
6.2.3 Equilibrium
Equilibrium is a state in a reversible chemical reaction where the rate of the forwards reaction equals the rate of the backwards reaction. This results in no net change in the concentrations of reactants and products over time.
Reversible and Irreversible Reactions
- Irreversible Reactions: These reactions proceed only in the forwards direction, converting reactants into products, and do not readily reverse under the same conditions.
- Reversible Reactions: These can proceed in both the forwards (from reactants to products) and backwards (from products to reactants) directions. When the rates of both reactions are equal, an equilibrium is established.
Equilibrium in Reversible Reactions:
When reversible reactions occur in a sealed container, none of the reactants or products can escape, allowing equilibrium to be established.
At equilibrium, the concentrations of reactants and products remain constant, although they are not necessarily equal. The relative amounts indicate the position of the equilibrium.
Position of Equilibrium:
The position of equilibrium can shift in response to changes in the conditions under which the reaction occurs. This shift alters the concentrations of reactants or products, depending on the nature of the changes.