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### Different Types of Entropies

Posted: **Tue Feb 11, 2020 5:53 pm**

by **Jason Wu 1E**

Through practice problems, I have come across various types of Entropies including S, Delta S, Delta S total, and Delta S surroundings. What do each one of them mean and how do they relate to each other? Thanks!

### Re: Different Types of Entropies

Posted: **Tue Feb 11, 2020 5:56 pm**

by **Megan Cao 1I**

S is just entropy itself

delta S is the change in entropy

delta S total is the total change in entropy within a universe ( S_{sys} + S_{surr})

delta S surroundings is the change in entropy within the surroundings

Hope this helps in some way!

### Re: Different Types of Entropies

Posted: **Sat Feb 15, 2020 8:34 pm**

by **Emma Popescu 1L**

Also when the reaction is reversible delta S total=0 so delta S system= - delta S surroundings

### Re: Different Types of Entropies

Posted: **Sun Feb 16, 2020 5:51 pm**

by **Helen Struble 2F**

Delta S and its variants (system, surroundings, total) represent a state function (change in entropy). We can find the value of this change through the equations given to us. However, because a delta valley represents a final value minus and initial value, we know that any system must have a set value for entropy at any given time, even if there is no change in the system. This is calculated using the Boltzmann equation.

### Re: Different Types of Entropies

Posted: **Sun Feb 16, 2020 7:56 pm**

by **Amy Kumar 1I**

The entropy of the system and surroundings added up equal the entropy of the surroundings. In cases where the entropy of the surroundings is 0, the entropy of the system equals -1*entropy of the surroundings.

### Re: Different Types of Entropies

Posted: **Wed Feb 19, 2020 12:15 pm**

by **RichBollini4G**

Megan Cao 1I wrote:S is just entropy itself

delta S is the change in entropy

delta S total is the total change in entropy within a universe ( S_{sys} + S_{surr})

delta S surroundings is the change in entropy within the surroundings

Hope this helps in some way!

thank you this was very helpful

### Re: Different Types of Entropies

Posted: **Thu Feb 20, 2020 2:50 pm**

by **Miriam Villarreal 1J**

The entropy of the surroundings will increase if energy (heat) is flowing into the surroundings from the system.If we are given the entropy changes of the system and surroundings, we can calculate total entropy change. The total entropy change is simply the sum of the system and the surroundings