### Units

Posted:

**Thu Mar 12, 2020 9:21 am**Are units for all rate constants M/s? And what does it mean if the s has a -1 attached in the denominator?

Created by Dr. Laurence Lavelle

https://lavelle.chem.ucla.edu/forum/

https://lavelle.chem.ucla.edu/forum/viewtopic.php?f=145&t=62134

Page **1** of **1**

Posted: **Thu Mar 12, 2020 9:21 am**

Are units for all rate constants M/s? And what does it mean if the s has a -1 attached in the denominator?

Posted: **Thu Mar 12, 2020 9:33 am**

the units for k are 1/M^(n-1)*s. n being the order of the reaction. Thus, if the reaction is first order the units are 1/s and second order 1/Ms and so on.

x-1 is just 1/x

x-1 is just 1/x

Posted: **Thu Mar 12, 2020 9:34 am**

The unit for the rate constant will depend on the overall reaction order. The rate will always be in units of M/s and each concentration will be in M. So the rate constant will always be in units so that when multiplied with the concentrations, the result will be in M/s.

Posted: **Thu Mar 12, 2020 11:12 am**

Zeroth order: M * s^-1

First order: s^-1

Second Order: M^-1 * s^-1

etc.

First order: s^-1

Second Order: M^-1 * s^-1

etc.

Posted: **Thu Mar 12, 2020 11:16 am**

rate constant units are determined by order of reaction