determining rate law

[sarahtang4B]

When given an experiment with 3 different reactants, once we find the order of one reactant, does it matter that it has to stay constant when you compare other reactions or does it not matter cause we already found the order?
On problem 7A17, I noticed the book compares experiment 2 and 3 but reactant a is not constant?....is this because we found A already?

[LorenzoDuvergne3I]

In that particular case I think it is because one of the reactants does not affect the rate law and so you only have to worry about keeping the other two constant.

[sophiebillings1E]

You should see which reactants affect the rate most of the time it will only be the slowest step, but it could also entail other steps.