PbBr2 (s) → Pb+2 (aq) + 2 Br-1 (aq)

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Reaction Type:

Dissociation of an ionic compound in water

Enthalpy of Reaction

[1ΔHf(Pb+2 (aq)) + 2ΔHf(Br-1 (aq))] - [1ΔHf(PbBr2 (s))]
[1(-1.7) + 2(-121.55)] - [1(-277.4)] = 32.6 kJ
32.60 kJ     (endothermic)

Entropy Change

[1ΔSf(Pb+2 (aq)) + 2ΔSf(Br-1 (aq))] - [1ΔSf(PbBr2 (s))]
[1(10.5) + 2(82.42)] - [1(161.13)] = 14.21 J/K
14.21 J/K     (increase in entropy)

Free Energy of Reaction (at 298.15 K)

From ΔGf° values:
[1ΔGf(Pb+2 (aq)) + 2ΔGf(Br-1 (aq))] - [1ΔGf(PbBr2 (s))]
[1(-24.4) + 2(-103.97)] - [1(-260.75)] = 28.41 kJ
28.41 kJ     (nonspontaneous)

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

Equilibrium Constant, K (at 298.15 K)

1.05318918286504E-05
This process is not favorable at 25°C.

Enter an initial concentration for the ionic compound. Upon hitting submit, Ksp (1.05318918286504E-05) will be used to calculate the equilibrium concentration for all species.

PbBr2 Pb+2 Br-1
Initial M   0 0
Change -x +x +2x
Equilibrium