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Quiz 2 Preparation

Posted: Thu Feb 23, 2017 12:21 am
by Elnaz Guivatchian 3L
Can someone please explain number 10 from the practice quiz in the course reader
Thanks

Re: Quiz 2 Preparation

Posted: Thu Feb 23, 2017 12:25 am
by Geoffrey Zhang 3I
You have to use the integrated rate law for second order reactions. After plugging the values in, you will see that the time it takes are different. I used 1/[A]subscript t = 1/[A]0 + kt

Re: Quiz 2 Preparation

Posted: Thu Feb 23, 2017 12:34 am
by Alex Dib 4H
We know its a second order reaction because of the exponent given in the rate law; rate = k[A]2

Using the integrated rate law for second order reactions, we can rearrange the equation and solve for time. Knowing that k is the same constant at both initial concentrations, we can ignore it. This gives t=1/[A]-1/[A]0. When plugging in initial and final concentrations for both 1.0M-->0.50M and 0.50M-->0.25M, we get different times, showing us that half life depends on initial concentration for second order reactions.