## Pseudo-First-Order Reaction

$\frac{d[R]}{dt}=-k[R]; \ln [R]=-kt + \ln [R]_{0}; t_{\frac{1}{2}}=\frac{0.693}{k}$

Abigail Urbina 1K
Posts: 102
Joined: Thu Jul 27, 2017 3:01 am

### Pseudo-First-Order Reaction

If we are working with a reaction that does not have an overall order of 1, what should we look for to know that we should turn it into a pseudo-first-order reaction?

Merzia Subhan 1L
Posts: 33
Joined: Thu Jul 13, 2017 3:00 am

### Re: Pseudo-First-Order Reaction

I believe the pseudo reactions are always going to be second order but one reactant's concentration is so high so when the one with the lesser concentration runs out, the big one barely changes so you can pretend that it didn't change and that its just a first order reaction with the reactant with the smaller concentration. When [B]o>>[A]o :
(1/[B])ln([A]o/[A])=kt
or
[A]=[A]o*e^(-[B]kt)

effective rate law: rate = k'[B]