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Topic: Half life  (Read 2894 times)

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Offline UG

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Half life
« on: May 28, 2010, 06:16:16 AM »
Hi, how does one find the half life of a reaction such as
d[Cl2]/dt = k[Cl2]1.5 ?
Does it involve integrating? If so, how :-\ ?
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Offline sjb

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Re: Half life
« Reply #1 on: May 28, 2010, 07:48:01 AM »
How would you do it, working from first principles, if it were first order?
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Offline UG

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Re: Half life
« Reply #2 on: May 28, 2010, 08:37:36 AM »
Integrate it
d[Cl2]/[Cl2] = k dt which becomes c - ln[Cl2] = kt
At t = 0 [Cl2] = [Cl2]0 and so c = [Cl2]0
Or ln([Cl2]0 / [Cl2]) = kt
After one half life [Cl2] = [Cl2]0/2
Or ln([Cl2]0 / ([Cl2]0/2)) = kt1/2
Giving ln(2) = kt1/2
and t1/2 = ln 2 /k
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Offline sjb

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Re: Half life
« Reply #3 on: May 31, 2010, 01:26:50 PM »
So follow a similar approach to the reaction order you have.
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