The rate law is an equation that expresses how the rate of a chemical reaction depends on the concentrations of reactants.
Key points:
- General form: For a reaction aA + bB → products, the rate law is:
- Rate = k [A]^m [B]^n
- k = rate constant (depends on temperature)
- m, n = reaction orders with respect to A and B (determined experimentally)
- Reaction order:
- m and n tell how sensitively the rate depends on each reactant’s concentration.
- Overall order = m + n
- Significance:
- Shows the relationship between concentration and reaction rate.
- Helps determine the mechanism of the reaction.
- Important notes:
- The exponents (m, n) are not necessarily equal to stoichiometric coefficients.
- k changes with temperature but not with concentration.
In short: The rate law tells us how fast a reaction occurs and how the reactant concentrations affect that speed.