ZnBr2 (s) → Zn+2 (aq) + 2 Br-1 (aq)

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Reaction Type:

Dissociation of an ionic compound in water

Enthalpy of Reaction

[1ΔHf(Zn+2 (aq)) + 2ΔHf(Br-1 (aq))] - [1ΔHf(ZnBr2 (s))]
[1(-153.9) + 2(-121.55)] - [1(-328.65)] = -68.35 kJ
-68.35 kJ     (exothermic)

Entropy Change

[1ΔSf(Zn+2 (aq)) + 2ΔSf(Br-1 (aq))] - [1ΔSf(ZnBr2 (s))]
[1(-112.1) + 2(82.42)] - [1(138.49)] = -85.75 J/K
-85.75 J/K     (decrease in entropy)

Free Energy of Reaction (at 298.15 K)

From ΔGf° values:
[1ΔGf(Zn+2 (aq)) + 2ΔGf(Br-1 (aq))] - [1ΔGf(ZnBr2 (s))]
[1(-147.1) + 2(-103.97)] - [1(-312.13)] = -42.91 kJ
-42.91 kJ     (spontaneous)

From ΔG = ΔH - TΔS:
-42.78 kJ     (spontaneous)

Equilibrium Constant, K (at 298.15 K)

32955283.718
This process is favorable at 25°C.

Enter an initial concentration for the ionic compound. Upon hitting submit, Ksp (32955283.718) will be used to calculate the equilibrium concentration for all species.

ZnBr2 Zn+2 Br-1
Initial M   0 0
Change -x +x +2x
Equilibrium