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### Homework, 6th edition, 15.35

Posted: Mon Mar 11, 2019 10:32 pm
Hi, I was wondering how I would use the second-order reaction (after I found k by using the half-life equation)?

### Re: Homework, 6th edition, 15.35

Posted: Tue Mar 12, 2019 12:02 am
You are given the [A]0 and you have k, from solving the half-life equation. You are trying to find time and you actually are given [A] as well. For example, in part a) you want to find how long it takes to decrease to one-sixteenth of the original which is [A] and you can figure that out by multiplying 1/16 by the [A]0 to give you [A]. Now you plug everything in to solve for t.

### Re: Homework, 6th edition, 15.35

Posted: Tue Mar 12, 2019 12:04 am
Use the formula t1/2= [A]/2k to solve for k, then modify the formula for the other proportions.
eg.
t1/16= 15[A]/16k
t1/4= 3[A]/4k
etc

### Re: Homework, 6th edition, 15.35

Posted: Tue Mar 12, 2019 12:46 am
You know the half-life equation for a second-order reaction is: t1/2 = 1 / k [A]o

Therefore, after finding k, you can use the integrated rate law 1/[A] = kt + 1/[A]o for a second-order reaction to find t.