3 CuS (s) + 8 HNO3 (aq) → 8 NO (g) + 3 CuSO4 (aq) + 4 H2O (ℓ)

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Stoichiometry

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 CuS            Mass: g HNO3           Mass: g or Solution Volume: mL of Concentration: mol/L NO             Mass: g or Gas Volume: L CuSO4          Mass: g H2O            Mass: g Heat Released: kJ

Enthalpy of Reaction

[8ΔHf(NO (g)) + 3ΔHf(CuSO4 (aq)) + 4ΔHf(H2O (ℓ))] - [3ΔHf(CuS (s)) + 8ΔHf(HNO3 (aq))]
[8(90.25) + 3(-844.5) + 4(-285.83)] - [3(-53.14) + 8(-207.36)] = -1136.52 kJ
-1,136.52 kJ     (exothermic)

Entropy Change

[8ΔSf(NO (g)) + 3ΔSf(CuSO4 (aq)) + 4ΔSf(H2O (ℓ))] - [3ΔSf(CuS (s)) + 8ΔSf(HNO3 (aq))]
[8(210.65) + 3(-79.5) + 4(69.91)] - [3(66.53) + 8(146.44)] = 355.23 J/K
355.23 J/K     (increase in entropy)

Free Energy of Reaction (at 298.15 K)

From ΔGf° values:
[8ΔGf(NO (g)) + 3ΔGf(CuSO4 (aq)) + 4ΔGf(H2O (ℓ))] - [3ΔGf(CuS (s)) + 8ΔGf(HNO3 (aq))]
[8(86.57) + 3(-679.11) + 4(-237.18)] - [3(-53.56) + 8(-111.34)] = -1242.09 kJ
-1,242.09 kJ     (spontaneous)

From ΔG = ΔH - TΔS:
-1242.43 kJ     (spontaneous)

Equilibrium Constant, K (at 298.15 K)

4.138677676e+217
This process is favorable at 25°C.