Ca(OH)2 (aq) + 2 NH4I (s) → CaI2 (aq) + 2 H2O (ℓ) + 2 NH3 (g)

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Reaction Type:

Double Displacement/Decomposition of Ammonium Hydroxide

Stoichiometry

Enter a mass or volume in one of the boxes below. Upon hitting submit, the stoichiometric equivalents will be calculated for the remaining reactants and products. All gases are assumed to be at STP.

Ca(OH)2        Mass: g  or Solution Volume: mL of Concentration: mol/L
NH4I           Mass: g
CaI2           Mass: g  or Solution Volume: mL of Concentration: mol/L
H2O            Mass: g
NH3            Mass: g  or Gas Volume: L

Enthalpy of Reaction

[1ΔHf(CaI2 (aq)) + 2ΔHf(H2O (ℓ)) + 2ΔHf(NH3 (g))] - [1ΔHf(Ca(OH)2 (aq)) + 2ΔHf(NH4I (s))]
[1(-653.21) + 2(-285.83) + 2(-46.11)] - [1(-1002.81) + 2(-201.42)] = 88.5600000000002 kJ
88.56 kJ     (endothermic)

Entropy Change

[1ΔSf(CaI2 (aq)) + 2ΔSf(H2O (ℓ)) + 2ΔSf(NH3 (g))] - [1ΔSf(Ca(OH)2 (aq)) + 2ΔSf(NH4I (s))]
[1(169.44) + 2(69.91) + 2(192.34)] - [1(-74.64) + 2(117.15)] = 534.28 J/K
534.28 J/K     (increase in entropy)

Free Energy of Reaction (at 298.15 K)

From ΔGf° values:
[1ΔGf(CaI2 (aq)) + 2ΔGf(H2O (ℓ)) + 2ΔGf(NH3 (g))] - [1ΔGf(Ca(OH)2 (aq)) + 2ΔGf(NH4I (s))]
[1(-656.72) + 2(-237.18) + 2(-16.48)] - [1(-868.1) + 2(-112.55)] = -70.8400000000001 kJ
-70.84 kJ     (spontaneous)

From ΔG = ΔH - TΔS:
-70.74 kJ     (spontaneous)

Equilibrium Constant, K (at 298.15 K)

2578229801634.39
This process is favorable at 25°C.