PbI2 (s) → Pb+2 (aq) + 2 I-1 (aq)

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Reaction Type:

Dissociation of an ionic compound in water

Enthalpy of Reaction

[1ΔHf(Pb+2 (aq)) + 2ΔHf(I-1 (aq))] - [1ΔHf(PbI2 (s))]
[1(-1.7) + 2(-55.19)] - [1(-175.39)] = 63.31 kJ
63.31 kJ     (endothermic)

Entropy Change

[1ΔSf(Pb+2 (aq)) + 2ΔSf(I-1 (aq))] - [1ΔSf(PbI2 (s))]
[1(10.5) + 2(111.29)] - [1(174.85)] = 58.23 J/K
58.23 J/K     (increase in entropy)

Free Energy of Reaction (at 298.15 K)

From ΔGf° values:
[1ΔGf(Pb+2 (aq)) + 2ΔGf(I-1 (aq))] - [1ΔGf(PbI2 (s))]
[1(-24.4) + 2(-51.59)] - [1(-173.59)] = 46.01 kJ
46.01 kJ     (nonspontaneous)

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

Equilibrium Constant, K (at 298.15 K)

8.68856836e-009
This process is not favorable at 25°C.

Enter an initial concentration for the ionic compound. Upon hitting submit, Ksp (8.68856836e-009) will be used to calculate the equilibrium concentration for all species.

PbI2 Pb+2 I-1
Initial M   0 0
Change -x +x +2x
Equilibrium