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Topic: Reaction rates & Rate constants  (Read 3887 times)

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Offline student8607

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Reaction rates & Rate constants
« on: February 01, 2009, 12:52:15 PM »
A certain first-order reaction has a rate constant of 1.0x10-3s-1 at 25 degrees C.

If the reaction rate doubles when the temperature is increased to 35 degrees C, what is the activation energy in kJ?

I am familiar with the equation to solve for Ea but how am I to determine my second rate constant just from knowing the reaction rate doubles?

Offline Yggdrasil

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Re: Reaction rates & Rate constants
« Reply #1 on: February 01, 2009, 12:56:20 PM »
You know that k35 / k25 = 2.  Can you write this ratio of rate constants in terms of activation energy?

Offline student8607

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Re: Reaction rates & Rate constants
« Reply #2 on: February 02, 2009, 07:20:14 PM »
If the rate doubles then the rate constant does as weel?

Ln(1.0x10-3 / 2.0x10-3) = -Ea/8.31 x (1/308 - 1/298)

?

Offline Yggdrasil

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Re: Reaction rates & Rate constants
« Reply #3 on: February 02, 2009, 10:45:41 PM »
I would assume that is what the problem means, although doubling the rate constant is not the only way to double the rate of reaction.

Offline student8607

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Re: Reaction rates & Rate constants
« Reply #4 on: February 03, 2009, 01:09:38 PM »
Ok, will go with that.
Thanks!

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