MgI2 (s) → Mg+2 (aq) + 2 I-1 (aq)

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Reaction Type:

Dissociation of an ionic compound in water

Enthalpy of Reaction

[1ΔHf(Mg+2 (aq)) + 2ΔHf(I-1 (aq))] - [1ΔHf(MgI2 (s))]
[1(-466.85) + 2(-55.19)] - [1(-364.01)] = -213.22 kJ
-213.22 kJ     (exothermic)

Entropy Change

[1ΔSf(Mg+2 (aq)) + 2ΔSf(I-1 (aq))] - [1ΔSf(MgI2 (s))]
[1(-138.07) + 2(111.29)] - [1(129.7)] = -45.19 J/K
-45.19 J/K     (decrease in entropy)

Free Energy of Reaction (at 298.15 K)

From ΔGf° values:
[1ΔGf(Mg+2 (aq)) + 2ΔGf(I-1 (aq))] - [1ΔGf(MgI2 (s))]
[1(-454.8) + 2(-51.59)] - [1(-358.15)] = -199.83 kJ
-199.83 kJ     (spontaneous)

From ΔG = ΔH - TΔS:
-199.75 kJ     (spontaneous)

Equilibrium Constant, K (at 298.15 K)

1.02482415383546E+35
This process is favorable at 25°C.

Enter an initial concentration for the ionic compound. Upon hitting submit, Ksp (1.02482415383546E+35) will be used to calculate the equilibrium concentration for all species.

MgI2 Mg+2 I-1
Initial M   0 0
Change -x +x +2x
Equilibrium