## Problem 9.85

$\Delta G^{\circ}= \Delta H^{\circ} - T \Delta S^{\circ}$

$\Delta G^{\circ}= -RT\ln K$

$\Delta G^{\circ}= \sum \Delta G_{f}^{\circ}(products) - \sum \Delta G_{f}^{\circ}(reactants)$

charlottesmith3f
Posts: 22
Joined: Fri Sep 25, 2015 3:00 am

### Problem 9.85

This question asks "potassium nitrate dissolves readily in water and its enthalpy of solution is +34.9kj/mol. Does the enthalpy of solution favor the dissolving process?" The answer says the enthalpy does not favor the dissolution process, but how would we know that? Don't we have to know enthalpy, entropy and temperature to calculate if a process is spontaneous?

Chem_Mod
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### Re: Problem 9.85

Positive enthalpy and negative entropy are "unfavorable" qualities that cause a reaction to TEND more towards being non-spontaneous. The fact that this dissolution is endothermic but still yet is spontaneous just means that it has a compensating high entropy increase.