Know Which Order It Is [ENDORSED]

[JaeHoCho1B]

Hello! I was wandering how can we tell what kind of order the reaction is based off the rate? Thank you so much for your help!

[Chem_Mod]

One way is based off how the rate varies with concentration. If the concentration increases two-fold and the rate increases two-fold, you know that the reaction is first order. Similarly, if the concentration increases two-fold and the rate increases by a factor of 4, then you know the reaction is second order.

[Desiree Martin 2A]

As well as this, another thing to consider is the overall order of the reaction. Depending on the amount of reactants, aA+bB=cC+dD, you must find the order of each reactant, then add the sum of the orders to get the OVERALL order. For example, let's say rate law =k[A]^2 * [B]^2, then the overall order is 2+2=4. From here, they would usually ask to find k. If given the table of values for different concentrations of A and B as well as the rate, then you would simply focus on one line, and plug in k=(rate of reaction)/[A]^2*[B]^2. Then once k is found, you have found the rate law for that reaction by plugging in the value of k to the original equation of the rate law.