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Key Words for First Order Reactions Half Life Problems

Posted: Tue Mar 06, 2018 1:05 am
by Silvino Jimenez 1A
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?

Re: Key Words for First Order Reactions Half Life Problems

Posted: Tue Mar 06, 2018 12:48 pm
by lizzygaines1D
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.

Re: Key Words for First Order Reactions Half Life Problems

Posted: Tue Mar 06, 2018 9:06 pm
by Brigitte Phung 1F
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