2 NH4Br (aq) + 1 Mg(OH)2 (s) → MgBr2 (aq) + 2 H2O (ℓ) + 2 NH3 (g)

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Reaction Type:

Double Displacement/Decomposition of Ammonium Hydroxide

Stoichiometry

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Heat Added: kJ
NH4Br          Mass: g  or Solution Volume: mL of Concentration: mol/L
Mg(OH)2        Mass: g
MgBr2          Mass: g
H2O            Mass: g
NH3            Mass: g  or Gas Volume: L

Enthalpy of Reaction

[1ΔHf(MgBr2 (aq)) + 2ΔHf(H2O (ℓ)) + 2ΔHf(NH3 (g))] - [2ΔHf(NH4Br (aq)) + 1ΔHf(Mg(OH)2 (s))]
[1(-709.95) + 2(-285.83) + 2(-46.11)] - [2(-254.06) + 1(-924.66)] = 58.9499999999998 kJ
58.95 kJ     (endothermic)

Entropy Change

[1ΔSf(MgBr2 (aq)) + 2ΔSf(H2O (ℓ)) + 2ΔSf(NH3 (g))] - [2ΔSf(NH4Br (aq)) + 1ΔSf(Mg(OH)2 (s))]
[1(26.77) + 2(69.91) + 2(192.34)] - [2(195.81) + 1(63.18)] = 96.47 J/K
96.47 J/K     (increase in entropy)

Free Energy of Reaction (at 298.15 K)

From ΔGf° values:
[1ΔGf(MgBr2 (aq)) + 2ΔGf(H2O (ℓ)) + 2ΔGf(NH3 (g))] - [2ΔGf(NH4Br (aq)) + 1ΔGf(Mg(OH)2 (s))]
[1(-662.74) + 2(-237.18) + 2(-16.48)] - [2(-183.34) + 1(-833.87)] = 30.49 kJ
30.49 kJ     (nonspontaneous)

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

Equilibrium Constant, K (at 298.15 K)

4.5507804027e-006
This process is not favorable at 25°C.