Key Words for First Order Reactions Half Life Problems


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Silvino Jimenez 1A
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Joined: Fri Sep 29, 2017 7:04 am

Key Words for First Order Reactions Half Life Problems

Postby Silvino Jimenez 1A » Tue Mar 06, 2018 1:05 am

I am having a hard time identifying the order of a reaction given half life reaction time t1/2.


Are there key words or phrases that indicate a reaction is first order when determining half life reaction time?

lizzygaines1D
Posts: 52
Joined: Thu Jul 13, 2017 3:00 am

Re: Key Words for First Order Reactions Half Life Problems

Postby lizzygaines1D » Tue Mar 06, 2018 12:48 pm

Usually the question will give you the order, and if it doesn't it should give the units of k. If the units are inverse time units, you'll know its first order etc. etc.

Brigitte Phung 1F
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Re: Key Words for First Order Reactions Half Life Problems

Postby Brigitte Phung 1F » Tue Mar 06, 2018 9:06 pm

I also believe the problems should always tell you the order of the reaction as 23, 25, 27, and many others also do. But in the case they don't, you can always check the units of k!
For your reference:
- zero-order: k is in units of mol * L^-1 * s^-1
- first-order: k is in units of s^-1
- second-order: k is in units of L * mol^-1 * s^-1


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