Explain the concept of equilibrium constants Kc... - SS2 Chemistry Chemical Equilibrium Question

Equilibrium constants, represented as Kc (for concentrations) and Kp (for partial pressures), quantify the relative concentrations or partial pressures of reactants and products at chemical equilibrium. They express the ratio of the concentrations or partial pressures of products to reactants, each raised to their stoichiometric coefficients.

For a general chemical reaction:

aA + bB ⇌ cC + dD

The equilibrium constant expression (Kc) is:

Kc = [C]^c [D]^d / [A]^a [B]^b

In the case of gaseous reactions, the equilibrium constant expression (Kp) is expressed in terms of partial pressures instead of concentrations.

The equilibrium constants provide valuable information about the position and extent of a reaction at equilibrium.

●     Magnitude of Kc or Kp: A large equilibrium constant (Kc or Kp) indicates that the products are favoured at equilibrium, whereas a small equilibrium constant indicates that the reactants are favoured. The magnitude of Kc or Kp reflects the degree of completion of the reaction.

●     Predicting the direction of the reaction: If the reaction quotient (Q) is compared to the equilibrium constant (Kc or Kp), the direction of the reaction can be determined. If Q < K, the forward reaction is favoured and will proceed to reach equilibrium in the forward direction. If Q > K, the reverse reaction is favoured and will proceed to reach equilibrium in the reverse direction. If Q = K, the system is already at equilibrium.

●     Shifting the equilibrium position: By changing the conditions of temperature, pressure, or concentration, the equilibrium position can be shifted to favour the formation of more products or reactants. Le Chatelier's Principle can be applied to understand how changes in conditions affect the equilibrium position.