NH4Br (s) → NH4+1 (aq) + Br-1 (aq)

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Reaction Type:

Dissociation of an ionic compound in water

Enthalpy of Reaction

[1ΔHf(NH4+1 (aq)) + 1ΔHf(Br-1 (aq))] - [1ΔHf(NH4Br (s))]
[1(-132.51) + 1(-121.55)] - [1(-270.83)] = 16.77 kJ
16.77 kJ     (endothermic)

Entropy Change

[1ΔSf(NH4+1 (aq)) + 1ΔSf(Br-1 (aq))] - [1ΔSf(NH4Br (s))]
[1(113.39) + 1(82.42)] - [1(112.97)] = 82.84 J/K
82.84 J/K     (increase in entropy)

Free Energy of Reaction (at 298.15 K)

From ΔGf° values:
[1ΔGf(NH4+1 (aq)) + 1ΔGf(Br-1 (aq))] - [1ΔGf(NH4Br (s))]
[1(-79.37) + 1(-103.97)] - [1(-175.31)] = -8.03 kJ
-8.03 kJ     (spontaneous)

From ΔG = ΔH - TΔS:
-7.93 kJ     (spontaneous)

Equilibrium Constant, K (at 298.15 K)

25.519573619
This process is favorable at 25°C.

Enter an initial concentration for the ionic compound. Upon hitting submit, Ksp (25.519573619) will be used to calculate the equilibrium concentration for all species.

NH4Br NH4+1 Br-1
Initial M   0 0
Change -x +x +x
Equilibrium