1. Forward and Reverse Reaction Rates:
At equilibrium, the forward reaction rate (products forming) becomes equal to the reverse reaction rate (reactants forming). This means that the concentrations of reactants and products are not changing over time. Mathematically, this can be expressed as:
Forward reaction rate = Reverse reaction rate
2. Equilibrium Constant (Kc or Kp):
The equilibrium constant (Kc for concentration-based reactions and Kp for pressure-based reactions) is a constant value that reflects the extent to which a reaction proceeds in either direction. At equilibrium, the equilibrium constant remains constant and its value can be calculated using the concentrations of reactants and products.
For a general reaction:
aA + bB ⇌ cC + dD
The equilibrium constant expression is:
Kc = [C]^c [D]^d / [A]^a [B]^b
where [A], [B], [C], and [D] represent the equilibrium concentrations of the respective species.
Note that for gaseous reactions, the equilibrium constant is expressed in terms of partial pressures instead of concentrations.
By maintaining these equal factors, a reversible chemical reaction reaches a state of dynamic equilibrium, where the interconversion between reactants and products continues, but the overall composition of the system remains unchanged.
