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### Entropy

Posted: Sun Jan 29, 2017 8:27 pm
Is entropy always increasing?

### Re: Entropy

Posted: Sun Jan 29, 2017 8:45 pm
Not always, but an increase in entropy is favorable for systems as opposed to a decrease in entropy.

### Re: Entropy

Posted: Mon Jan 30, 2017 10:27 pm
Entropy is a state function that acts as a measurement of disorder. Thus, a positive entropy change correlates to greater disorder. Because the sum of the entropy change in the system and its surroundings must be positive for a reaction to be spontaneous, all spontaneous reactions occur through an increase in entropy. (Overall, the universe favors an increase in entropy.)

Change in entropy is negative when there is a decrease in temperature; therefore, a system's entropy decreases when it cools.

### Re: Entropy

Posted: Mon Jan 30, 2017 11:50 pm
Why is it that when looking at the formula for entropy, S=q/T, when T increases, S should decrease but in actuality when a substance is heated, the entropy increases because the atoms are moving at a faster rate and creating more chaos?

### Re: Entropy

Posted: Tue Jan 31, 2017 10:00 am
I think that might happen because when the temperature is increased, the system is given more heat too as heat increases the temperature. therefore as T increases, q actually also increases. And the increase in q is usually greater than that of T which is why in actuality when a system is heated entropy increases.

### Re: Entropy

Posted: Tue Jan 31, 2017 1:23 pm
Keep in mind it's CHANGE in entropy = q(rev)/T, so for entropy changes at higher temperatures, it's less significant than for entropy changes at lower temperatures. The same amount of heat could be transferred into the system, but for a lower temperature, that amount of heat is going to cause more entropy change than at a lower temperature. This makes sense conceptually because at low temperatures molecules are more rigid, but if at least one molecule starts to move around, it will excite and further transfer that disorder to other molecules within its vicinity. Hope this helps! :)