Chemical Equilibrium

Definition and Concept

• Chemical equilibrium: a state in which the rates of forward and reverse reactions are equal, and the concentrations of reactants and products remain constant.
• Equilibrium is a dynamic state, meaning that reactions are still occurring, but at equal rates.

Characteristics of Equilibrium

• Reversible reactions: equilibrium can only be achieved in reversible reactions, where the reaction can proceed in both forward and reverse directions.
• Constant concentrations: concentrations of reactants and products remain constant at equilibrium.
• No net change: there is no net change in the concentrations of reactants and products at equilibrium.

Equilibrium Constants

• Equilibrium constant (K): a constant that represents the ratio of product concentrations to reactant concentrations at equilibrium.
• Kc: equilibrium constant expressed in terms of concentrations (mol/L).
• Kp: equilibrium constant expressed in terms of partial pressures.
• Kc = Kp (RT)^Δn: relationship between Kc and Kp, where R is the gas constant, T is temperature in Kelvin, and Δn is the change in moles of gas.

Factors Affecting Equilibrium

• Concentration: increasing the concentration of reactants or products can shift the equilibrium to the right or left.
• Temperature: increasing the temperature can shift the equilibrium to the right or left, depending on the reaction.
• Pressure: increasing the pressure can shift the equilibrium to the right or left, depending on the reaction.
• Catalysts: catalysts do not affect the equilibrium position, but can increase the rate of reaching equilibrium.

Le Châtelier's Principle

• Le Châtelier's Principle: when a system in equilibrium is subjected to a change, it will respond in a way that tends to counteract the change.
• Examples:
  • Increasing the concentration of reactants: equilibrium shifts to the right.
  • Decreasing the concentration of products: equilibrium shifts to the right.
  • Increasing the temperature: equilibrium shifts to the right or left, depending on the reaction.

Chemical Equilibrium

• A state where forward and reverse reaction rates are equal, and reactant and product concentrations remain constant.
• Dynamic state, meaning reactions still occur, but at equal rates.

Reversible Reactions and Equilibrium

• Equilibrium can only be achieved in reversible reactions, where the reaction can proceed in both forward and reverse directions.
• Reversible reactions allow for the attainment of equilibrium.

Characteristics of Equilibrium

• Concentrations of reactants and products remain constant at equilibrium.
• No net change in reactant and product concentrations at equilibrium.

Equilibrium Constants

• Equilibrium constant (K) represents the ratio of product concentrations to reactant concentrations at equilibrium.
• Kc: equilibrium constant expressed in terms of concentrations (mol/L).
• Kp: equilibrium constant expressed in terms of partial pressures.
• Kc = Kp (RT)^Δn: relationship between Kc and Kp, where R is the gas constant, T is temperature in Kelvin, and Δn is the change in moles of gas.

Factors Affecting Equilibrium

• Increasing reactant concentration: shifts equilibrium to the right.
• Increasing product concentration: shifts equilibrium to the left.
• Increasing temperature: shifts equilibrium to the right or left, depending on the reaction.
• Increasing pressure: shifts equilibrium to the right or left, depending on the reaction.
• Catalysts: do not affect equilibrium position, but increase the rate of reaching equilibrium.

Le Châtelier's Principle

• When a system in equilibrium is subjected to a change, it responds to counteract the change.
• Examples:
  • Increasing reactant concentration: equilibrium shifts to the right.
  • Decreasing product concentration: equilibrium shifts to the right.
  • Increasing temperature: equilibrium shifts to the right or left, depending on the reaction.