CaF2 (s) → Ca+2 (aq) + 2 F-1 (aq)

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Reaction Type:

Dissociation of an ionic compound in water

Enthalpy of Reaction

[1ΔHf(Ca+2 (aq)) + 2ΔHf(F-1 (aq))] - [1ΔHf(CaF2 (s))]
[1(-542.83) + 2(-332.6)] - [1(-1219.64)] = 11.6099999999999 kJ
11.61 kJ     (endothermic)

Entropy Change

[1ΔSf(Ca+2 (aq)) + 2ΔSf(F-1 (aq))] - [1ΔSf(CaF2 (s))]
[1(-53.14) + 2(-13.8)] - [1(68.87)] = -149.61 J/K
-149.61 J/K     (decrease in entropy)

Free Energy of Reaction (at 298.15 K)

From ΔGf° values:
[1ΔGf(Ca+2 (aq)) + 2ΔGf(F-1 (aq))] - [1ΔGf(CaF2 (s))]
[1(-553.54) + 2(-278.8)] - [1(-1167.34)] = 56.2 kJ
56.20 kJ     (nonspontaneous)

From ΔG = ΔH - TΔS:
56.22 kJ     (nonspontaneous)

Equilibrium Constant, K (at 298.15 K)

1.4244202015e-010
This process is not favorable at 25°C.

Enter an initial concentration for the ionic compound. Upon hitting submit, Ksp (1.4244202015e-010) will be used to calculate the equilibrium concentration for all species.

CaF2 Ca+2 F-1
Initial M   0 0
Change -x +x +2x
Equilibrium