Ag2S (s alpha orthorhombic) + 2 HCl (aq) → 2 AgCl (s) + H2S (g)

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Reaction Type:

Double Displacement

Stoichiometry

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Ag2S           Mass: g
HCl            Mass: g  or Solution Volume: mL of Concentration: mol/L
AgCl           Mass: g
H2S            Mass: g  or Gas Volume: L

Enthalpy of Reaction

[2ΔHf(AgCl (s)) + 1ΔHf(H2S (g))] - [1ΔHf(Ag2S (s alpha orthorhombic)) + 2ΔHf(HCl (aq))]
[2(-127) + 1(-20.17)] - [1(-32.59) + 2(-167.15)] = 92.72 kJ
92.72 kJ     (endothermic)

Entropy Change

[2ΔSf(AgCl (s)) + 1ΔSf(H2S (g))] - [1ΔSf(Ag2S (s alpha orthorhombic)) + 2ΔSf(HCl (aq))]
[2(96.3) + 1(205.77)] - [1(144.01) + 2(56.48)] = 141.4 J/K
141.40 J/K     (increase in entropy)

Free Energy of Reaction (at 298.15 K)

From ΔGf° values:
[2ΔGf(AgCl (s)) + 1ΔGf(H2S (g))] - [1ΔGf(Ag2S (s alpha orthorhombic)) + 2ΔGf(HCl (aq))]
[2(-109.8) + 1(-33.05)] - [1(-40.67) + 2(-131.25)] = 50.52 kJ
50.52 kJ     (nonspontaneous)

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

Equilibrium Constant, K (at 298.15 K)

1.40859597148993E-09
This process is not favorable at 25°C.

Reference(s):

Silberberg, Martin S. Chemistry: The Molecular Nature of Matter and Change 4th ed.; McGraw-Hill: Boston, MA, 2006; p 128.

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