What is the order of a reaction?

The order of a reaction tells us how the rate of a chemical reaction depends on the concentration of reactants.

Key points:

1. Definition:
   • For a reaction aA + bB → products, if the rate law is Rate = k [A]^m [B]^n,
     • m = order with respect to A
     • n = order with respect to B
     • Overall order = m + n
2. Interpretation:
   • m = 1: Rate is directly proportional to [A] (first order with respect to A).
   • m = 2: Rate is proportional to [A]² (second order with respect to A).
   • m = 0: Rate is independent of [A] (zero order).
3. Determination:
   • Reaction order is determined experimentally, not from the balanced equation.
4. Significance:
   • Helps understand reaction kinetics and predict how changing concentrations affects the rate.

In short: The order of a reaction is the exponent of reactant concentration in the rate law, indicating how strongly that reactant affects the reaction speed.