Chemical equilibrium is the state in a reversible chemical reaction where the rates of the forward and reverse reactions are equal, so the concentrations of reactants and products remain constant over time.
Key points:
- Reversible reaction: Only reactions that can go both forward and backward can reach equilibrium.
- No net change: Even though reactions continue to occur, there is no overall change in the amounts of reactants and products.
- Closed system: Equilibrium is generally established in a closed system, where no reactants or products are added or removed.
- Dynamic nature: Chemical equilibrium is dynamic, meaning molecules keep reacting, but the system appears stable.
- Equilibrium constant (K): The relative concentrations of reactants and products at equilibrium are related by K, which is fixed at a given temperature.
Example: The Haber process (nitrogen + hydrogen ⇌ ammonia) reaches chemical equilibrium when ammonia is being formed and decomposed at the same rate, keeping concentrations constant.
It’s basically the “balanced state” of a reversible reaction.