KCl (s) → K+1 (aq) + Cl-1 (aq)

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Reaction Type:

Dissociation of an ionic compound in water

Enthalpy of Reaction

[1ΔHf(K+1 (aq)) + 1ΔHf(Cl-1 (aq))] - [1ΔHf(KCl (s))]
[1(-252.4) + 1(-167.15)] - [1(-435.89)] = 16.34 kJ
16.34 kJ     (endothermic)

Entropy Change

[1ΔSf(K+1 (aq)) + 1ΔSf(Cl-1 (aq))] - [1ΔSf(KCl (s))]
[1(102.5) + 1(56.48)] - [1(82.68)] = 76.3 J/K
76.30 J/K     (increase in entropy)

Free Energy of Reaction (at 298.15 K)

From ΔGf° values:
[1ΔGf(K+1 (aq)) + 1ΔGf(Cl-1 (aq))] - [1ΔGf(KCl (s))]
[1(-283.3) + 1(-131.25)] - [1(-408.32)] = -6.23000000000002 kJ
-6.23 kJ     (spontaneous)

From ΔG = ΔH - TΔS:
-6.41 kJ     (spontaneous)

Equilibrium Constant, K (at 298.15 K)

12.3455234977868
This process is favorable at 25°C.

Enter an initial concentration for the ionic compound. Upon hitting submit, Ksp (12.3455234977868) will be used to calculate the equilibrium concentration for all species.

KCl K+1 Cl-1
Initial M   0 0
Change -x +x +x
Equilibrium