CoCl2 (s) → Co+2 (aq) + 2 Cl-1 (aq)

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Reaction Type:

Dissociation of an ionic compound in water

Enthalpy of Reaction

[1ΔHf(Co+2 (aq)) + 2ΔHf(Cl-1 (aq))] - [1ΔHf(CoCl2 (s))]
[1(-58.16) + 2(-167.15)] - [1(-312.54)] = -79.92 kJ
-79.92 kJ     (exothermic)

Entropy Change

[1ΔSf(Co+2 (aq)) + 2ΔSf(Cl-1 (aq))] - [1ΔSf(CoCl2 (s))]
[1(-112.97) + 2(56.48)] - [1(109.16)] = -109.17 J/K
-109.17 J/K     (decrease in entropy)

Free Energy of Reaction (at 298.15 K)

From ΔGf° values:
[1ΔGf(Co+2 (aq)) + 2ΔGf(Cl-1 (aq))] - [1ΔGf(CoCl2 (s))]
[1(-54.39) + 2(-131.25)] - [1(-269.87)] = -47.02 kJ
-47.02 kJ     (spontaneous)

From ΔG = ΔH - TΔS:
-47.37 kJ     (spontaneous)

Equilibrium Constant, K (at 298.15 K)

172984012.97
This process is favorable at 25°C.

Enter an initial concentration for the ionic compound. Upon hitting submit, Ksp (172984012.97) will be used to calculate the equilibrium concentration for all species.

CoCl2 Co+2 Cl-1
Initial M   0 0
Change -x +x +2x
Equilibrium