KNO3 (s) → K+1 (aq) + NO3-1 (aq)

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Reaction Type:

Dissociation of an ionic compound in water

Enthalpy of Reaction

[1ΔHf(K+1 (aq)) + 1ΔHf(NO3-1 (aq))] - [1ΔHf(KNO3 (s))]
[1(-252.4) + 1(-207.36)] - [1(-492.71)] = 32.95 kJ
32.95 kJ     (endothermic)

Entropy Change

[1ΔSf(K+1 (aq)) + 1ΔSf(NO3-1 (aq))] - [1ΔSf(KNO3 (s))]
[1(102.5) + 1(146.44)] - [1(132.93)] = 116.01 J/K
116.01 J/K     (increase in entropy)

Free Energy of Reaction (at 298.15 K)

From ΔGf° values:
[1ΔGf(K+1 (aq)) + 1ΔGf(NO3-1 (aq))] - [1ΔGf(KNO3 (s))]
[1(-283.3) + 1(-111.34)] - [1(-393.13)] = -1.50999999999999 kJ
-1.51 kJ     (spontaneous)

From ΔG = ΔH - TΔS:
-1.64 kJ     (spontaneous)

Equilibrium Constant, K (at 298.15 K)

1.8388879824
This process is close to or at equilibrium at 25°C.

Enter an initial concentration for the ionic compound. Upon hitting submit, Ksp (1.8388879824) will be used to calculate the equilibrium concentration for all species.

KNO3 K+1 NO3-1
Initial M   0 0
Change -x +x +x
Equilibrium

Reference(s):

Ebbing, Darrell D. General Chemistry 3rd ed.; Houghton Mifflin Company: Boston, MA, 1990; p 226.

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