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Topic: Reaction Rates  (Read 5302 times)

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Offline 2clients

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Reaction Rates
« on: February 17, 2009, 03:26:40 PM »
Hello,

I honestly do not know where to start and I believe this homework question may be farther than where we are in class.  I think it involves the Arrenius expression, but I do not know for sure and if so what other information is needed.

The uncatalyzed decomposition of hydrogen peroxide (into water and oxygen gas) has an activation energy of 45.3 kJ mol-1.  How much faster will the rate of decomposition be at 30°C than 10°C?

Thank you!
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Offline Borek

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Re: Reaction Rates
« Reply #1 on: February 17, 2009, 03:42:48 PM »
Direct application of Arrhenius equation.
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Offline 2clients

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Re: Reaction Rates
« Reply #2 on: February 17, 2009, 03:53:02 PM »
Okay, thank you.  So, I know the expression is k= Ae^(-Ea/RT) , and I know constant R and T, but what is A? I'm also assuming Ea is 45300 J and e is the mathematical constant e?
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Offline 2clients

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Re: Reaction Rates
« Reply #3 on: February 17, 2009, 03:56:22 PM »
Actually, I guess A would not change the ratio, so I can plug in any number.  I got the ratio of k to be about 3.55, so about 3.55 times faster?
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Offline Borek

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Re: Reaction Rates
« Reply #4 on: February 17, 2009, 04:33:23 PM »
Looks OK to me. A is just a constant, so when comparing speeds at different temperatures it cancels out.
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Offline 2clients

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Re: Reaction Rates
« Reply #5 on: February 17, 2009, 04:53:32 PM »
I really appreciate the help, thank you.  I took General Chemistry I in NY and now I'm taking Gen Chem II in California.  It seems they covered some topics we didn't cover in NY, and vice-versa, so I feel a little behind already.
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Offline Borek

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Re: Reaction Rates
« Reply #6 on: February 17, 2009, 04:59:58 PM »
Well, be an optimist and feel a little bit ahead - finally there are things they don't know yet ;)
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