MgBr2 (s) → Mg+2 (aq) + 2 Br-1 (aq)

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Reaction Type:

Dissociation of an ionic compound in water

Enthalpy of Reaction

[1ΔHf(Mg+2 (aq)) + 2ΔHf(Br-1 (aq))] - [1ΔHf(MgBr2 (s))]
[1(-466.85) + 2(-121.55)] - [1(-524.26)] = -185.69 kJ
-185.69 kJ     (exothermic)

Entropy Change

[1ΔSf(Mg+2 (aq)) + 2ΔSf(Br-1 (aq))] - [1ΔSf(MgBr2 (s))]
[1(-138.07) + 2(82.42)] - [1(117.15)] = -90.38 J/K
-90.38 J/K     (decrease in entropy)

Free Energy of Reaction (at 298.15 K)

From ΔGf° values:
[1ΔGf(Mg+2 (aq)) + 2ΔGf(Br-1 (aq))] - [1ΔGf(MgBr2 (s))]
[1(-454.8) + 2(-103.97)] - [1(-503.75)] = -158.99 kJ
-158.99 kJ     (spontaneous)

From ΔG = ΔH - TΔS:
-158.74 kJ     (spontaneous)

Equilibrium Constant, K (at 298.15 K)

7.1679140114e+027
This process is favorable at 25°C.

Enter an initial concentration for the ionic compound. Upon hitting submit, Ksp (7.1679140114e+027) will be used to calculate the equilibrium concentration for all species.

MgBr2 Mg+2 Br-1
Initial M   0 0
Change -x +x +2x
Equilibrium