## Reaction Order

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

bonnie_schmitz_1F
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### Reaction Order

How do we know if a reaction is first/second order? and What does it mean for a reaction to be first/second order?

armintaheri
Posts: 68
Joined: Fri Sep 28, 2018 12:26 am

### Re: Reaction Order

It depends on the sum of all exponents in the rate law. The rate law can only be calculated experimentally.

Elizabeth Kim 4E
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Joined: Fri Sep 28, 2018 12:29 am

### Re: Reaction Order

It depends on the exponents

Ibrahim Malik 1H
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### Re: Reaction Order

A reaction would be first-order if the exponents on the elements in the rate law add up to 1. Likewise, the reaction would be second-order if the exponents on the elements in the rate law add up to 2.

Sarah Fatkin 4I
Posts: 71
Joined: Fri Sep 28, 2018 12:27 am

### Re: Reaction Order

We can determine if a reaction is first or second order using the equation rate = k[A]^n[B]^m. If n and m add up to one, it is a first order reaction. If n and m add to two, it is a second order reaction. Also, if a reaction is first order, then the graph of ln[A] vs t will have a slope of -k. If a reaction is second order, then the graph of 1/[A] vs t will have a slope of k. Hope this helps!

bonnie_schmitz_1F
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Thank you!