# How can Entropy increase/decrease?

I think there are 2 ways but i'm not quite sure

Posted Sun 29th May, 2011 @ 21:11 by Chris

The second law of thermodynamics states that the entropy of an isolated system always increases or remains constant. It can never decrease if it isolated (a contained environment) e.g. vacuum

Answered Tue 31st May, 2011 @ 14:19 by Amritpal Mundra
Edited by Amritpal Mundra on Thu 2nd June, 2011 @ 14:33

The second law of thermodynamics also states that the entropy of a system that is not isolated may decrease. In a room for example.

Answered Tue 31st May, 2011 @ 14:22 by Amritpal Mundra
Edited by Amritpal Mundra on Tue 31st May, 2011 @ 14:23

Chris wrote:

I think there are 2 ways but i'm not quite sure

I changed it read again. decreases if un-isolated! otherwise it can't decrease when in an isolated environment!

Answered Tue 31st May, 2011 @ 16:54 by Amritpal Mundra

Via Change of state

Increase liquid to gas becauses there is more disorder e.g particles are free to move about where as  liquid disorder is smaller because particles are fixed in one place.

Hope this is better

Answered Wed 1st June, 2011 @ 19:44 by sara

Entropy is a measure of the disorder in a system. Solids are more ordered, because, well, they're pretty much fixed, whereas liquids are more disordered because molecules move over each other, and gases are even more disordered because they're all over the place. So, gases have the highest entropy, and solids have the lowest entropy, although the entropy value will vary from compound to compound.

Generally: if there are more gaseous molecules in the products of a reaction than there are in the reactants, entropy has increased, and if there are less, then it has decreased.

If a solid melts into a liquid, or dissolves in a liquid, then there has also been an increase in entropy.

Hope that helps :)

Answered Thu 2nd June, 2011 @ 16:30 by Fool

Amritpal Mundra  -  "The second law of thermodynamics states that the entropy of an isolated system always increases or remains constant. It can never decrease!

The second law of thermodynamics also states that the entropy of a system that is not isolated may decrease. In a room for example."

You just said it can never decrease, but it may decrease.. WHAT. Please explain, i don't understand.

Answered Tue 31st May, 2011 @ 16:40 by Chris

Yes - the more gaseous molecules in a system, the more disorder there is. therefore entropy increases if a solid/liquid changes into a gas.

Answered Thu 2nd June, 2011 @ 12:43 by Chris