## Negative Rates

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

Emily Warda 2L
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### Negative Rates

Is it possible to have negative rates in chemical kinetics? What would this indicate?

I notice that a negative sign is used in the average rate of consumption of R formula to ensure that the rate is positive— is ensuring a positive rate always a necessary precaution to take in kinetics?

Ozhen Atoyan 1F
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### Re: Negative Rates

You sound like you have the correct idea, I would also like to know if it is possible to have a negative rate. I know we can't have negative time or energy, but I am not sure if the same idea applies to rates as well.

Sean Monji 2B
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### Re: Negative Rates

If the rate is negative for the reactant after doing the math, that means it is increasing over time. I think in that case you would switch the chemical equation around, as the reactants become the product and the product become the reactants.
I hope that makes sense

mayasinha1B
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### Re: Negative Rates

A negative rate would mean the reaction is occurring in the backwards direction.

Andrea ORiordan 1L
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### Re: Negative Rates

An overall rate of reaction is not negative-- that would just be referring to the reverse reaction. A reactant's concentration is decreasing, so we use a negative sign to denote that. However, the product increases in concentration, and so we say that the overall rate of the reaction is positive. As mentioned in class today, k can never be negative, so the overall rate of a reaction will always be positive (unless you are referring to the rate of the reverse reaction, in which case, that would be mentioned).