Study Notes
Reversible reactions are those where products can revert to reactants, indicated by the symbol ⇌. Equilibrium in a closed system occurs when the forward and reverse reaction rates are equal, and concentrations remain constant. The position of equilibrium can be influenced by changes in pressure, concentration, and temperature, as explained by Le Chatelier's Principle.
- Reversible Reaction — a chemical reaction where products can revert to reactants. Example: N2 (g) + 3H2 (g) ⇌ 2NH3 (g) in the Haber process.
- Equilibrium — a state in a closed system where the forward and reverse reaction rates are equal. Example: Concentrations of reactants and products remain constant.
- Le Chatelier's Principle — states that if a system at equilibrium is disturbed, it will adjust to minimize the disturbance. Example: Increasing pressure in the Haber process shifts equilibrium to produce more ammonia.
Exam Tips
Key Definitions to Remember
- Reversible Reaction: A reaction where products can revert to reactants
- Equilibrium: When the forward and reverse reaction rates are equal
- Le Chatelier's Principle: System adjusts to minimize changes at equilibrium
Common Confusions
- Confusing reversible reactions with irreversible ones
- Misunderstanding how changes in conditions affect equilibrium
Typical Exam Questions
- What happens to the equilibrium position if pressure is increased in the Haber process? It shifts to the right, increasing ammonia yield.
- How does increasing temperature affect an exothermic reversible reaction? It shifts the equilibrium position to the left.
- What is the role of a catalyst in a reversible reaction? It speeds up both forward and reverse reactions equally.
What Examiners Usually Test
- Understanding of reversible reactions and equilibrium
- Ability to predict changes in equilibrium position with changing conditions
- Knowledge of the Haber and Contact processes, including conditions and reactions