## Units [ENDORSED]

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

Ryan Neis 2L
Posts: 53
Joined: Fri Sep 29, 2017 7:04 am

### Units

What are the units for zero, first, and second-order reactions?

Andy Nguyen 1A
Posts: 56
Joined: Thu Jul 27, 2017 3:00 am

### Re: Units

The unit for k in a 0 order reaction is mol/(L*s). In a first order reaction, k is in 1/s. In a second order reaction, k is L/(mol*s).

Katie Lam 1B
Posts: 52
Joined: Fri Sep 29, 2017 7:06 am

### Re: Units

The units for the rate constant changes depending on the order of reaction, but the rate itself is always in mol/(L*s).

Justin Folk 3I
Posts: 43
Joined: Wed Sep 21, 2016 2:56 pm

### Re: Units

What about units for a 1.5 order?

Seth_Evasco1L
Posts: 54
Joined: Thu Jul 27, 2017 3:00 am

### Re: Units

Units of k for a reaction order of 1.5 would most likely have units of L0.5*mol-0.5*s-1.

Liz White 1K
Posts: 35
Joined: Thu Jul 13, 2017 3:00 am

### Re: Units  [ENDORSED]

As a general formula to calculate the units of the rate constant for any reaction order n, you can use the equation:

units of k = (L/mol)n-1 / s