## 15.39a

$aR \to bP, Rate = -\frac{1}{a} \frac{d[R]}{dt} = \frac{1}{b}\frac{d[P]}{dt}$

JamesAntonios 1E
Posts: 70
Joined: Fri Sep 29, 2017 7:04 am

### 15.39a

For a, because the reaction is 2A-->B + C, why isn't there a 2 in the reaction. If we are solving the differential rate law -1/2 d[A]/dt=k[A]^2, we get -1/2 d[A]/[A]^2= kdt. If we multiply the 2 to the other side, we are left with -d[A]/[A]^2=2kdt. If we integrate both sides, we get 1/[A]=2kt + 1/[A]o. However, the answer key does not use this equation. Why not, please?

Alyssa Parry Disc 1H
Posts: 53
Joined: Sat Jul 22, 2017 3:01 am

### Re: 15.39a

I'm not quite sure why they don't use that specifically but I am pretty sure that coefficients don't really affect anything

rkusampudi
Posts: 58
Joined: Fri Sep 29, 2017 7:04 am

### Re: 15.39a

Perhaps because it is looking at the concentration and not the number of moles.

miznaakbar
Posts: 55
Joined: Thu Jul 13, 2017 3:00 am
Been upvoted: 4 times

### Re: 15.39a

In lecture when we derived the differential rate law for second order reactions, we assumed a=1. For our purposes, it seems like they want us to assume that the coefficients do not affect the reaction (like the solutions manual shows), though I'm not really sure why they would not want us to take coefficients into account.