## 9.85

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

Jessica Lutz 2E
Posts: 56
Joined: Fri Sep 29, 2017 7:04 am

### 9.85

The question states:
Potassium nitrate dissolves readily in water, and its enthalpy of solution is 34.9 kJ mol 1. (a) Does the enthalpy of solution favor the dissolving process? (b) Is the entropy change of the system likely to be positive or negative when the salt dissolves? (c) Is the entropy change of the system primarily a result of changes in positional disorder or thermal disorder? (d) Is the entropy change of the surroundings primarily a result of changes in positional disorder or thermal disorder? (e) What is the driving force for the dissolution of KNO3?
I don't understand the explanation in the solutions manual for part a and I don't understand how we are supposed to know the answer to part e. Any help for this question in general would be great!

Rana YT 2L
Posts: 49
Joined: Thu Jul 27, 2017 3:01 am

### Re: 9.85

a) a positive enthalpy would result in the dissolving to be unfavorable because a positive enthalpy would result in a positive ∆G value and a negative enthalpy would result in the dissolving to be favorable because a negative enthalpy would result in negative ∆G.

RyanS2J
Posts: 32
Joined: Thu Jul 27, 2017 3:00 am

### Re: 9.85

b) The entropy generally increases for a reaction wherein a salt (a highly stable and structured compound) is dissolved into its component ions. Thus, for the dissolving of potassium nitrate in aqueous solution, the entropy increases, yielding a positive deltaS.