NaCl (s) → Na+1 (aq) + Cl-1 (aq)

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Reaction Type:

Dissociation of an ionic compound in water

Enthalpy of Reaction

[1ΔHf(Na+1 (aq)) + 1ΔHf(Cl-1 (aq))] - [1ΔHf(NaCl (s))]
[1(-240.1) + 1(-167.15)] - [1(-410.99)] = 3.74000000000001 kJ
3.74 kJ     (endothermic)

Entropy Change

[1ΔSf(Na+1 (aq)) + 1ΔSf(Cl-1 (aq))] - [1ΔSf(NaCl (s))]
[1(59) + 1(56.48)] - [1(72.38)] = 43.1 J/K
43.10 J/K     (increase in entropy)

Free Energy of Reaction (at 298.15 K)

From ΔGf° values:
[1ΔGf(Na+1 (aq)) + 1ΔGf(Cl-1 (aq))] - [1ΔGf(NaCl (s))]
[1(-261.9) + 1(-131.25)] - [1(-384.05)] = -9.09999999999997 kJ
-9.10 kJ     (spontaneous)

From ΔG = ΔH - TΔS:
-9.11 kJ     (spontaneous)

Equilibrium Constant, K (at 298.15 K)

39.295220881
This process is favorable at 25°C.

Enter an initial concentration for the ionic compound. Upon hitting submit, Ksp (39.295220881) will be used to calculate the equilibrium concentration for all species.

NaCl Na+1 Cl-1
Initial M   0 0
Change -x +x +x
Equilibrium

Reference(s):

Ebbing, Darrell D. General Chemistry 3rd ed.; Houghton Mifflin Company: Boston, MA, 1990; p 310.

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