A very simple reaction A + B → C + D, where A and B are the reactants and C and D are the products, we can find the order of reaction by using the rate equation: rate = k [A]ᵐ [B]ⁿ Note that (m and n) are not coefficients of the equation, they are the reaction order of each reactant.

Calculate ( dfrac {Delta y} {Delta x}) for the first and second points. The concentration is the (y) value, while time is the (x) value. Do the same for the second and third point. If the reaction is zero order with regard to the reactant, the numbers will be the same.

Consider a general reaction: aA+bB Rightarrow cC+dD. aA+bB ⇒ cC +dD. Suppose the rate expression for this reaction is: -r_a=kA^xB^y. −ra = kAxBy. Here, x x and y y indicate how sensitive the rate is to the change in concentration of A and B. Hence, the order of this reaction is x + y x+y.