## 9.5

Jessica Nunez 1I
Posts: 58
Joined: Thu Jul 13, 2017 3:00 am

### 9.5

What is the total entropy change of a process in which 40.0 kJ of energy is transferred as heat from a large reservoir at 800. K to one at 200. K?

For 9.5, the student solutions manual uses a negative sign for (delta)S = -40000 J/800 K, and I do not know why.

Jared Smith 1E
Posts: 51
Joined: Fri Sep 29, 2017 7:04 am

### Re: 9.5

I think that the reason that it is negative is due to the fact that the first reservoir lost heat, and transferred that heat to the second reservoir, meaning that it gained heat. Losing heat is negative, gaining is positive.

Jenny Cheng 2K
Posts: 30
Joined: Fri Sep 29, 2017 7:05 am
Been upvoted: 1 time

### Re: 9.5

ΔS(total) = -q/T(1) + q/T(2)
The first reservoir loses heat, so the q should be negative. The second reservoir gains the heat that the first reservoir loses, so the q should be positive.

Kyung_Jin_Kim_1H
Posts: 53
Joined: Thu Jul 27, 2017 3:00 am

### Re: 9.5

It is a transfer of heat, so thinking back to our ice cube in water problems, one will be positive and the other negative.

Troy Tavangar 1I
Posts: 50
Joined: Fri Sep 29, 2017 7:04 am

### Re: 9.5

It is because the first reservoir is losing heat.

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