## writing rate law

$aR \to bP, Rate = -\frac{1}{a} \frac{d[R]}{dt} = \frac{1}{b}\frac{d[P]}{dt}$

Emily Kennedy 4L
Posts: 57
Joined: Fri Sep 28, 2018 12:25 am
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### writing rate law

why do we only look at the reactants when writing a rate law from a mechanism?

gwynlu1L
Posts: 62
Joined: Fri Sep 28, 2018 12:19 am

### Re: writing rate law

I believe it is because you are trying to observe the instantaneous rate at the beginning of the rxn, before the product starts to go back to reactants (reverse rxn). If we tried to include products in the rate law, as in looking at the rates at a later time in the reaction, it would overcomplicate it. Therefore, the only concentrations that matter at the beginning of a rxn are the concentrations of the reactants.

Rachel Yoo 1F
Posts: 65
Joined: Fri Sep 28, 2018 12:24 am

### Re: writing rate law

I believe it is because the rate law is in terms of the products so reactants are the ones affecting the production rate