Rate Determining Step

[Jiayi Wu 3J]

How do we know which one is the slow step/rate-determining step?

[shevanti_kumar_1E]

If you are given the overall rate law expression then the reactants in the expression should match the reactants in the slow step, unless its an intermediate.

[Catie Donohue 2K]

I agree, if the slow step is not explicitly given to you then I would assume we would be given the overall rate law. Then, you can just form the elementary rate laws until you find one that matches the overall rate law. This will probably involve using the pre-equilibrium method, and you can substitute out any intermediates in the elementary step's rate law to obtain your final answer.

[sophia kosturos 2B]

if you are given reaction rates and observe them, you should be able to tell which has the slowest rate, and this would be the rate-determining step because this step must be completed before the reaction can be complete.

[Taha 2D]

it is the one shown in the rate law

[Shrinidhy Srinivas 3L]

Usually, the problem will tell you which step is the slow step. If a step is designated to be the slow step, that automatically means that that step will be the rate-determining step. You can then find the rate law accordingly. Sometimes a problem will give you an overall rate law and ask you to determine the slow step. In this case, you would have to test out all of the steps to see which one would match the rate law and determine the slow step that way.