Reaction Mechanism Intermediates

[Jonathon Jauregui]

When looking at a reaction mechanism I know that the slowest step is the rate-determining test and know how to solve when there is an intermediate in the rate reaction to replace it. I just want to understand the reasoning behind replacing the intermediate in the rate reaction with other concentrations and the rate constants from another step.

[Lan Wei 3I]

Hi,

I'm assuming you are talking about question #13 from this week's achieve. Intermediates are produced in one step and consumed in a later step, so they do not appear in the overall rate law, nor does it appear in the overall reaction. This is why we must substitute it with an alternative expression by using the reactants, which are present in the overall reaction.