Equilibrium

Introduction:
- Equilibrium refers to a state of balance or stability in a system where the forward and reverse reactions occur at equal rates.
- It is a dynamic process where reactions continue to occur, but there is no net change in the concentrations of reactants and products.
- Equilibrium can be achieved in various chemical reactions, including acid-base reactions, precipitation reactions, and gas-phase reactions.

The Law of Mass Action:
- The Law of Mass Action states that the rate of a chemical reaction is directly proportional to the product of the concentrations of the reactants.
- For a general reaction: aA + bB ⇌ cC + dD, the rate expression can be given as:
rate = k[A]^a[B]^b, where [A] and [B] are the concentrations of reactants A and B, respectively, and k is the rate constant.
- The equilibrium constant, Kc, is defined as the ratio of the product of the equilibrium concentrations of the products to the product of the equilibrium concentrations of the reactants.
- For the reaction: aA + bB ⇌ cC + dD, the equilibrium constant expression is given as:
Kc = ([C]^c[D]^d) / ([A]^a[B]^b)

Types of Equilibrium:
1. Homogeneous Equilibrium:
- Homogeneous equilibrium refers to a system where all the reactants and products are present in the same phase.
- Example: N2(g) + 3H2(g) ⇌ 2NH3(g)
- In this case, the concentrations of N2, H2, and NH3 are considered when writing the equilibrium constant expression.

2. Heterogeneous Equilibrium:
- Heterogeneous equilibrium refers to a system where the reactants and products are present in different phases.
- Example: CaCO3(s) ⇌ CaO(s) + CO2(g)
- In this case, the concentration of CO2(g) is considered, while the concentration of CaCO3(s) and CaO(s) remain constant and are not included in the equilibrium constant expression.

Factors Affecting Equilibrium:
1. Concentration:
- According to Le Chatelier's principle, if the concentration of a reactant or product is increased, the equilibrium will shift in the direction that consumes or reduces that species.
- If the concentration of a reactant or product is decreased, the equilibrium will shift in the direction that produces or increases that species.

2. Pressure (for gas-phase reactions):
- For reactions involving gases, changes in pressure can affect the equilibrium position.
- According to Le Chatelier's principle, an increase in pressure will cause the equilibrium to shift in the direction that reduces the total number of moles of gas.
- A decrease in pressure will cause the equilibrium to shift in the direction that increases the total number of moles of gas.

3. Temperature:
- Changes in temperature can also affect the equilibrium position.
- If the reaction is exothermic (heat is released), an increase in temperature will shift the equilibrium in the direction that consumes or reduces heat.
- If the reaction is endothermic (heat is absorbed), an increase in temperature will shift the equilibrium in the direction that produces or increases heat.

Equilibrium Constants:
- The equilibrium constant, Kc, is a numerical value that represents the ratio of the concentrations of products to reactants at equilibrium.
- It is a characteristic

Https://edurev.page.link/ctPWoNe1zdFegu658