## Pseudo orders

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

Jasmine Botello 2F
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### Pseudo orders

Are there any homework problems in the textbook that talk about this because I feel like I need practice on this or is it more of a conceptual thing??

Austin Ho 1E
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### Re: Pseudo orders

I'm pretty sure it's more of a conceptual thing. You just have to know how to identify a pseudo first order and the concepts about it, but there's not a whole lot of actual questions about them.

Jasmine Botello 2F
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Joined: Fri Sep 29, 2017 7:04 am

### Re: Pseudo orders

how would you identify them?

Chem_Mod
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### Re: Pseudo orders

Jasmine Botello 2F wrote:how would you identify them?

When one of your reactants are in excess compared to the other reactants. For instance, if you have 10 M of A and react with 0.001 M of B according to the following reaction A + B --> C, you can imagine that the concentration of A will vary very little and can thus be considered to be at constant concentration. As a result, even if the reaction may be a second order reaction (Rate = k[A][B]), with [A] being constant, the rate will seem like it is a first order reaction (Rate = k[A]o[B], with [A]o being the initial concentration of A, which is constant). This is known as a pseudo first order reaction.