When to use steady-state vs. pre-equilibrium

[Haesoo Kim 3O]

When we are deriving the overall rate law implied by a proposed mechanism, when do we use the steady-state approach and when do we use pre-equilibrium approach, and why? Thank you.

[Justin Le 2I]

Both techniques will get you the same answer but in this class, I think we are just going to use the pre-equilibrium approach that Dr. Lavelle went over in class.

[Sanmeet Atwal 1D]

Justin's right, for this class we use the pre-equilibrium approach to find the overall rate law!

[104607508]

when writing the rate laws for elementary reactions the textbook says "The reverse of step 2 is too slow to affect the rate and so is not included." (634) how are we supposed to know when a reaction is to slow to include?

[juliana alden 2D]

We only use the reverse reaction if the step is at equilibrium, because the step is too slow there is no bottleneck or build and therefore the step is not equilibrium and the reverse reaction is not taken into account. The problem should indicate if the step is slow or fast, where fast steps are usually considered to be at equilibrium and therefore have a forward and reverse reaction rate