MgF2 (s) → Mg+2 (aq) + 2 F-1 (aq)

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Reaction Type:

Dissociation of an ionic compound in water

Enthalpy of Reaction

[1ΔHf(Mg+2 (aq)) + 2ΔHf(F-1 (aq))] - [1ΔHf(MgF2 (s))]
[1(-466.85) + 2(-332.6)] - [1(-1124.24)] = -7.81000000000017 kJ
-7.81 kJ     (exothermic)

Entropy Change

[1ΔSf(Mg+2 (aq)) + 2ΔSf(F-1 (aq))] - [1ΔSf(MgF2 (s))]
[1(-138.07) + 2(-13.8)] - [1(57.24)] = -222.91 J/K
-222.91 J/K     (decrease in entropy)

Free Energy of Reaction (at 298.15 K)

From ΔGf° values:
[1ΔGf(Mg+2 (aq)) + 2ΔGf(F-1 (aq))] - [1ΔGf(MgF2 (s))]
[1(-454.8) + 2(-278.8)] - [1(-1071.1)] = 58.6999999999998 kJ
58.70 kJ     (nonspontaneous)

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

Equilibrium Constant, K (at 298.15 K)

5.1955640464e-011
This process is not favorable at 25°C.

Enter an initial concentration for the ionic compound. Upon hitting submit, Ksp (5.1955640464e-011) will be used to calculate the equilibrium concentration for all species.

MgF2 Mg+2 F-1
Initial M   0 0
Change -x +x +2x
Equilibrium