## When entropy=0 [ENDORSED]

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

James_Duffek_2B
Posts: 7
Joined: Wed Sep 21, 2016 2:55 pm

### When entropy=0

Is it possible for a system to have no entropy? What would such a system look like?

becky a 3D
Posts: 7
Joined: Sat Jul 09, 2016 3:00 am

### Re: When entropy=0

a system is said to have 0 entropy when there is only 1 microstate molecules can be in, meaning all molecules are in the same energy level. The equation S= k lnW shows that entropy equals 0 when w (which represents the total # of microstates for molecules) is equal to one, that is because ln(1)=0 . A system that has 0 entropy is found in diatomic molecules where the total number of possible positions is only 1 (e.g. O2) and at low temperatures (0 K) where there is no thermal disorder.

danae_blodgett_1H
Posts: 18
Joined: Sat Jul 23, 2016 3:00 am

### Re: When entropy=0

What type of question would be asked in the case that entropy is equal to zero?

Molika Soben_3J
Posts: 27
Joined: Wed Sep 21, 2016 3:00 pm

### Re: When entropy=0  [ENDORSED]

In the textbook, question 21 of chapter nine asks you to calculate the entropy of a solid nanostructure made of 64 molecules in which the molecules are aligned in the same direction. Since it is only arranged in one way, W would be 1^64 which would equal 1 and plug it into the equation for entropy and you will get 0 for the value of entropy compared to if the molecules lie in 4 directions which in that case W would be 4^64. Entropy will be equal to 0 if a system can only be prepared or arranged in one way.