If the overall reaction is the sum of the order of the reagents, and:
Zero order = changing concentration of the reactant does not affect the reaction rate.
First order = doubling the concentration of any reactant doubles the reaction rate
Second order = doubling the concentration of any reactant quadruples the reaction
Experiments show that, in the following reaction, doubling A doubled the reaction rate and the overall reaction order was 2. What is the reaction order?
1, 2, 3, 4 or 5
Note: there are very few, if any 3rd order reactions in any one reactant. Assume the temp is constant.
Rate = k*[A]^n * [B]^m
If you look at your reaction First Order definition, if we double A ...
This solution explains how to determine the overall reaction.