CHEMISTRY COMMUNITY

For 7A.15 a), how are we supposed to find the values of m and n when [C] is constantly changing?

When you find the ratio between Rate 1 and Rate 4, you will see that [C] will be in zeroth order. That means that now the differential rate law is k[A][B]. Now, when finding the orders of A and B, you don't need to take into account [C] because the reaction does not depend on the concentration of [C].

In figuring out the answer, you would see that the concentration of C would be changing, but you do not take it into account since it is a zero order. The differential rate law would instead be rate = k[A][B] instead, so this way, you are able to focus on the differences between each experiment from concentrations of A and B. This would make analysis much more straightforward in comparison so you're able to determine the orders for each.

How are you supposed to know something is Zeroth order? is there a specific rule to know that it is zeroth order?