Entropy as Temperature Increases

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

Tamera Scott 1G
Posts: 65
Joined: Fri Sep 28, 2018 12:27 am

Entropy as Temperature Increases

As temperature increases, ∆S decreases, and I know this is because temperature is the denominator of the equation ∆S= -∆H/T, but what is the conceptual reason for this?

David Effio 1H
Posts: 38
Joined: Wed Feb 14, 2018 3:01 am

Re: Entropy as Temperature Increases

Let me try to set up a situation for you:

Entropy is essentially a measure of disorder. With that logic:

Say we transfer 1000 J of energy to a system. This system is currently sitting at 283.15 K (10 C). Here the entropy would be 3.53 J/K, a high entropy.
Then let's say we add 1000J of energy to a system at 573.15 K (300 C). Entropy is now 1.74 J/K, much lower.

If we were to see the atoms moving, you would see the atoms with higher changes in entropy going from standing almost completely still to moving all over the place - more change in the disorder of the molecules.
However, molecules already moving substantially fast in hotter systems, like those at 300 C, will not see such a large change in the disorder of their molecules because they are already moving pretty fast.

The book gives a great example as well:
Say you sneeze in a very quiet place, like a library. Here, the system goes from being completely silent (cool system) to very loud, hence higher change in entropy. However, if you sneeze in an already loud place (hot system), like the busy streets of Los Angeles, the change in entropy will be much lower, since everything around you is already pretty loud.

I hope that helps!

805087225
Posts: 30
Joined: Thu Jun 07, 2018 3:00 am

Re: Entropy as Temperature Increases

Here, we notice the average change. If the temperature is already very high, then the particles are already moving around a lot and fast, so the change in disorder would be minuscule.
But from a low temperature system, the change in the disorder is more visible, and hence the entropy change is highly calculable.