Units of entropy [ENDORSED]

$\Delta S = \frac{q_{rev}}{T}$

Cowasjee_Sanaea_3E
Posts: 27
Joined: Fri Jul 22, 2016 3:00 am

Units of entropy

I had always thought that the units for entropy was: joules/moles x kelvin
But is it possible for it to be just:
joules/kelvin?

Nerissa_Low_2F
Posts: 23
Joined: Fri Jul 15, 2016 3:00 am

Re: Units of entropy

Yes it is possible. Entropy can be equal to q/T, and the units for q is Joules and Kelvin for T, so the units of your answer can be Joules/Kelvin.

Rochelle Ellison 2H
Posts: 29
Joined: Wed Sep 21, 2016 3:00 pm

Re: Units of entropy

The same rules of units apply as when we were calculating enthalpy. If the moles cancel out, then your final answer should not be J/(K * mol) unless the problem is asking for your answer per mole in which case you would divide your answer by the number of moles given in the problem or the chemical equation. If you follow your units throughout the problem you should end up with the right units in your answer.

Aiden_Hsu_1M
Posts: 9
Joined: Wed Sep 21, 2016 2:55 pm

Re: Units of entropy  [ENDORSED]

If the problem asks for entropy per unit of a substance, it would be J/(K*mol) or J/(K*mol) if it's per unit mass. Otherwise you can probably assume they just want the answer in J/K.