Irreversible and Reversible Reactions

Irreversible Reactions: These reactions proceed in one direction only, converting reactants completely into products. Once the reaction is complete, no significant amount of reactants remains, and the reaction does not achieve a state of equilibrium.

Reversible Reactions: These reactions can proceed in both forward and reverse directions. As products are formed, they can react to reform the original reactants. Over time, the rates of the forward and reverse reactions become equal, leading to a dynamic equilibrium where the concentrations of reactants and products remain constant.

Characteristics of Chemical Equilibrium

Dynamic Equilibrium: At equilibrium, the forward and reverse reactions occur at the same rate. Although the reaction continues at the molecular level, there is no net change in the concentrations of reactants and products.

At equilibrium, the concentrations of reactants and products do not change over time, but they are not necessarily equal. Le Chatelier’s Principle: If a system at equilibrium is disturbed (e.g., by changing concentration, pressure, or temperature), the system will adjust to partially counteract the disturbance and re-establish equilibrium.

Equilibrium Constant Kc

Definition: Kc is the equilibrium constant for a reaction in solution, expressed in terms of the molar concentrations of reactants and products.

the equilibrium constant K is expressed as:Kc= $\frac{[C]^c [D]^d}{[A]^a [B]^b}$

Equilibrium Constant (Kp)

Kp is the equilibrium constant for reactions involving gases, expressed in terms of the partial pressures of the gaseous reactants and products.

aA(g) + bB(g) ⇌ aA(g) + bB(g)

the equilibrium constant K is expressed as ; $K_p = \frac{(P_C)^c (P_D)^d}{(P_A)^a (P_B)^b} $