DGorxn for NH4NO3(s) ? NH4NO3(aq)

From tables of thermodynamic data we find

DHorxn = +25.7 kJ

DSorxn = +108.7 J/K or +0.1087 kJ/K

DGorxn = +25.7 kJ - (298 K)(+0.1087 kJ/K)

= -6.7 kJ

Reaction is product-favored

. . . in spite of positive DHorxn.

Reaction is “entropy driven”

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