## Pseudo-First-Order Reaction

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

Meigan Wu 2E
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### Pseudo-First-Order Reaction

How do we know if a reaction can be treated as a pseudo-first-order reaction?

Layal Suboh 1I
Posts: 61
Joined: Fri Sep 28, 2018 12:23 am

### Re: Pseudo-First-Order Reaction

I think when are there are multiple reactants, we treat the reaction as a pseudo-reaction. It's difficult to study a reaction when the concentrations of multiple reactants are changing, so we let one reactant change and keep the others constant.

Celine Cheng 1H
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### Re: Pseudo-First-Order Reaction

Is this what we see when we use experimental data and change the concentrations of the reactants in separate trials?

Posts: 65
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### Re: Pseudo-First-Order Reaction

it certain sense it is since in that we are trying to isolate the reactants to figure out each of their pseudo reaction orders independent of the other reactants

Megan_Ervin_1F
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### Re: Pseudo-First-Order Reaction

I do not understand, what exactly is a psuedo reaction?

Brian Kwak 1D
Posts: 88
Joined: Fri Sep 28, 2018 12:17 am

### Re: Pseudo-First-Order Reaction

A reaction which is not first-order reaction naturally but made first order by increasing or decreasing the concentration of one or the other reactant is known as Pseudo first order reaction. In pseudo-first order reactions, we are basically isolating a reactant by increasing the concentration of the other reactants. When the other reactants are in excess, change in their concentrations does not affect the reaction much, Therefore, now the reaction only depends on the concentration of the isolated reactant. The concentrations of all the other reactants are taken as constant in the rate law. Thus, the order of reaction becomes one. Hope this clarifies it a bit.