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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: moun7 on October 07, 2014, 02:13:22 PM

Title: Question about rate constants and reaction rates with regards to ozone depletion
Post by: moun7 on October 07, 2014, 02:13:22 PM

Hello,

I have a question in which I am asked to calculate the loss rate of ozone with respect to the following reaction.

Cl + O₃ -> ClO + O₂, k(T) = 2.9x10^-11e^-260/T, where T is in Kelvins

If I am doing this correctly,

rate = k[Cl][O₃]

Now the next part asks me to calculate the rate loss of ozone with respect to the following two reactions. The concentrations and temperature are given.

Cl + O₃ -> ClO + O₂, k(T) = 2.9x10^-11e^-260/T

OH + O₃ -> HO₂ + O₂, k(T) = 2.0x10^-12e^-940/T

Do I determine the overall reaction? If so, how do I go about determining the overall rate constant? Or do I calculate the reaction rates individually and combine them? If so, how do I combine them?

Thanks a bunch.

Title: Re: Question about rate constants and reaction rates with regards to ozone depletion
Post by: mjc123 on October 07, 2014, 05:47:31 PM

Quote

If I am doing this correctly, rate = k[Cl][O3]

I assume that's correct, but k should have units that tell you the overall order of reaction.

Quote

Do I determine the overall reaction? If so, how do I go about determining the overall rate constant? Or do I calculate the reaction rates individually and combine them? If so, how do I combine them?

There isn't one "overall" reaction, there are 2 reactions going on in parallel. Calculate the rates of each reaction and add them together.

Title: Re: Question about rate constants and reaction rates with regards to ozone depletion
Post by: moun7 on October 07, 2014, 06:28:28 PM

Awesome. Thanks.

I kind of thought that was the case I just couldn't find anywhere that confirmed it.