CaO (s) + 2 NH4Cl (s) → 2 NH3 (g) + H2O (g) + 1 CaCl2 (s)

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Stoichiometry

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CaO            Mass: g
NH4Cl          Mass: g
NH3            Mass: g  or Gas Volume: L
H2O            Mass: g  or Gas Volume: L
CaCl2          Mass: g

Enthalpy of Reaction

[2ΔHf(NH3 (g)) + 1ΔHf(H2O (g)) + 1ΔHf(CaCl2 (s))] - [1ΔHf(CaO (s)) + 2ΔHf(NH4Cl (s))]
[2(-46.11) + 1(-241.82) + 1(-795.8)] - [1(-635.13) + 2(-314.43)] = 134.15 kJ
134.15 kJ     (endothermic)

Entropy Change

[2ΔSf(NH3 (g)) + 1ΔSf(H2O (g)) + 1ΔSf(CaCl2 (s))] - [1ΔSf(CaO (s)) + 2ΔSf(NH4Cl (s))]
[2(192.34) + 1(188.72) + 1(104.6)] - [1(38.2) + 2(94.56)] = 450.68 J/K
450.68 J/K     (increase in entropy)

Free Energy of Reaction (at 298.15 K)

From ΔGf° values:
[2ΔGf(NH3 (g)) + 1ΔGf(H2O (g)) + 1ΔGf(CaCl2 (s))] - [1ΔGf(CaO (s)) + 2ΔGf(NH4Cl (s))]
[2(-16.48) + 1(-228.59) + 1(-748.1)] - [1(-603.54) + 2(-202.97)] = -0.170000000000073 kJ
-0.17 kJ     (close to or at equilibrium)

From ΔG = ΔH - TΔS:
-0.22 kJ     (close to or at equilibrium)

Equilibrium Constant, K (at 298.15 K)

1.0709874178
This process is close to or at equilibrium at 25°C.

Reference(s):

Kotz, John C., Treichel, Paul, and Weaver, Gabriela. Chemistry & Chemical Reactivity 6th ed.; Thomson Brooks/Cole: Belmont, CA, 2006; pp 167-8.

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