Pseudo rate laws

[Ashley Kenney 1E]

Can someone explain what a pseudo rate law is, and in what context we would use a pseudo rate law? Also, practically speaking, why is it important for us to use and understand pseudo rate laws? Thank you in advance!

[eden tefera 2B]

When you have a reaction that is not first order and you want to determine one of the reactant's concentration, you can use a pseudo-first-order reaction in which one of the reactants is in great excess, essentially remaining constant as the reaction progresses. This allows you to determine concentration using a first order reaction.

[Nathan Tran 4K]

Essentially, because the concentration of one reactant is so high, we can neglect the excess reactant to make the rate law easier to work with. So for a second order reaction involving two concentrations, if one of the concentrations is high, we can ignore it, and say the reaction is a pseudo first order reaction where the reaction only depends on one reactant.