Final answer:
To determine the reaction order in a reactant, you must examine the exponents in the rate law equation, which describe how the rate depends on reactant concentrations. These exponents are obtained experimentally and are added together to find the overall reaction order.
Step-by-step explanation:
To determine the reaction order of a reactant, you must identify the exponent of each species in the rate law equation. The rate law equation typically has a form that indicates the reaction rate dependence on the concentrations of reactants, like 'rate = k[A]^m[B]^n', where k is the rate constant, [A] and [B] are the concentrations of reactants A and B, and m and n represent the reaction orders with respect to A and B, respectively.
The reaction order can be zero, first, second, or even a fraction and is determined experimentally by measuring changes in reactant concentrations over time. The sum of the exponents, m + n, gives the overall reaction order. These values are crucial because they describe the degree to which the reaction rate depends on the concentration of each reactant. Therefore, if the rate law is 'rate = k[A]^1[B]^2', the reaction is first order with respect to A and second order with respect to B, and third order overall due to the sum of the exponents being 1 + 2.