CuCN (s) → Cu+1 (aq) + CN-1 (aq)

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Reaction Type:

Dissociation of an ionic compound in water

Enthalpy of Reaction

[1ΔHf(Cu+1 (aq)) + 1ΔHf(CN-1 (aq))] - [1ΔHf(CuCN (s))]
[1(71.67) + 1(150.62)] - [1(94.98)] = 127.31 kJ
127.31 kJ     (endothermic)

Entropy Change

[1ΔSf(Cu+1 (aq)) + 1ΔSf(CN-1 (aq))] - [1ΔSf(CuCN (s))]
[1(40.58) + 1(94.14)] - [1(90)] = 44.72 J/K
44.72 J/K     (increase in entropy)

Free Energy of Reaction (at 298.15 K)

From ΔGf° values:
[1ΔGf(Cu+1 (aq)) + 1ΔGf(CN-1 (aq))] - [1ΔGf(CuCN (s))]
[1(50) + 1(172.38)] - [1(108.37)] = 114.01 kJ
114.01 kJ     (nonspontaneous)

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

Equilibrium Constant, K (at 298.15 K)

1.0597434895e-020
This process is not favorable at 25°C.

Enter an initial concentration for the ionic compound. Upon hitting submit, Ksp (1.0597434895e-020) will be used to calculate the equilibrium concentration for all species.

CuCN Cu+1 CN-1
Initial M   0 0
Change -x +x +x
Equilibrium