Determination of the order of a reaction:
The simplest means of determining the order of a reaction is to measure the rate v at different concentrations a of the reactants. A plot of ln v against ln a is then a straight line with slope equal to the order. As well as the overall order it is useful to know the order with respect to each reactant, which can be found by altering the concentration of each reactant separately, keeping the other concentrations constant. The slope of the line is then equal to the order with respect to the variable reactant. For example, if the reaction is second-order in A and first-order in B,