CaI2 (s) → Ca+2 (aq) + 2 I-1 (aq)

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Reaction Type:

Dissociation of an ionic compound in water

Enthalpy of Reaction

[1ΔHf(Ca+2 (aq)) + 2ΔHf(I-1 (aq))] - [1ΔHf(CaI2 (s))]
[1(-542.83) + 2(-55.19)] - [1(-536.81)] = -116.4 kJ
-116.40 kJ     (exothermic)

Entropy Change

[1ΔSf(Ca+2 (aq)) + 2ΔSf(I-1 (aq))] - [1ΔSf(CaI2 (s))]
[1(-53.14) + 2(111.29)] - [1(145.27)] = 24.17 J/K
24.17 J/K     (increase in entropy)

Free Energy of Reaction (at 298.15 K)

From ΔGf° values:
[1ΔGf(Ca+2 (aq)) + 2ΔGf(I-1 (aq))] - [1ΔGf(CaI2 (s))]
[1(-553.54) + 2(-51.59)] - [1(-533.13)] = -123.59 kJ
-123.59 kJ     (spontaneous)

From ΔG = ΔH - TΔS:
-123.61 kJ     (spontaneous)

Equilibrium Constant, K (at 298.15 K)

4.50024354956003E+21
This process is favorable at 25°C.

Enter an initial concentration for the ionic compound. Upon hitting submit, Ksp (4.50024354956003E+21) will be used to calculate the equilibrium concentration for all species.

CaI2 Ca+2 I-1
Initial M   0 0
Change -x +x +2x
Equilibrium