## Homework question

$\frac{d[R]}{dt}=-k; [R]=-kt + [R]_{0}; t_{\frac{1}{2}}=\frac{[R]_{0}}{2k}$

Megan Purl 1E
Posts: 49
Joined: Fri Sep 29, 2017 7:07 am

### Homework question

How would one express the units for rate constants when the concentrations are in moles per liter and time is in seconds for zero-order reactions?

RyanS2J
Posts: 32
Joined: Thu Jul 27, 2017 3:00 am

### Re: Homework question

For a zero order reaction, since rate = k, the units of k would simply be moles per liter per second, or mol•L^-1•s^-1.

Gevork 2E
Posts: 32
Joined: Fri Sep 29, 2017 7:05 am
Been upvoted: 1 time

### Re: Homework question

Hi,

I think it would also be better to know where the units are coming from with the use of the equation that we used in class.
rate = k[A]^n

Using this, let's see what happens when we are in a third order reaction (just an example, you can use this for anything):
k = rate/[A]^3
= mol x L^-1 x s^-1/ (mol x L^-1)^3
= L^2 x mol^-2 x s^-1