AS Chemistry: Reversible reaction & Dynamic Equilibrium

• Definition of Reversible reaction

  A reaction that can move in a forward direction and backward direction. Products change back into reactants.

  
• Reversible reaction with water

  Water ⇌ Ice
• Reversible reaction - Haber Process

  N₂(g) + 3H₂(g) ⇌ 2NH₃(g
• Reversible reaction - hydration and dehydration process of copper(II) sulfate

  CuSO₄·5H₂O (blue) ⇌ CuSO₄ (white) + 5H₂O
• What is Dynamic equilibrium

  Where forward and backward reaction occur at same time, with same rate, resulting in no net change in concentration of reactants or products.
• What is required for Dynamic Equilibrium?

  Closed system, substances cant enter or leave.
• What type of reaction can reach Dynamic equilibrium?


  Reversible reaction
• How can you speed up Dynamic Equilibrium?

  Catalyst, lowers activation energy.
• How does Dynamic Equilibrium ensure Equilibrium?

  Rate of reactions are same.

  Net concentrations of components of reactions mixture remain constant. Not equal.
• Dynamic Equilibrium in saturated solution of Copper (II) Sulfate

  When saturated solution of Copper (II) Sulfate is in equilibrium with undissolved solid Copper (II) Sulfate crystals. Dissolution and recrystallization occur at same rate, keeping concentration of solution constant.
• How can radioactive tracers be used to demonstrate dynamic equilibrium?


  Adding radioactive Copper (II) Sulfate crystals to saturated solution, radioactivity becomes evenly distributed between dissolved ions and undissolved crystals over time, proving exchange.
• Definition of Equilibrium mixture

  Balance of reactants and products at equilibium
• How can Dynamic Equilibrium mixture develop during chemical changes.

  If its mostly products, and hardly any reactants, its reached completion (E.g Magnesium in air)

  If its more reactants and less products, reaction cannot happen (E.g Water vapour at room temperature, difficult to detect any hydrogen or oxygen)
• What happens to concentration of reactants and product at equilibrium?

  Concentration reach steady value, forward and reverse reactions occur at same rate.
• What are macroscopic properties

  At equilibrium there's no observable change, properties that we can see or measure (concentration of reactants and products) remain constant
• Concentration-time graph for a reaction reaching dynamic equilibrium

  As concentration of reactants decrease, concentration of products increases until both reach steady values.