ZnS (s sphalerite) + 2 HCl (aq) → ZnCl2 (aq) + H2S (g)

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Stoichiometry

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Heat Added: kJ
ZnS            Mass: g
HCl            Mass: g  or Solution Volume: mL of Concentration: mol/L
ZnCl2          Mass: g
H2S            Mass: g  or Gas Volume: L

Enthalpy of Reaction

[1ΔHf(ZnCl2 (aq)) + 1ΔHf(H2S (g))] - [1ΔHf(ZnS (s sphalerite)) + 2ΔHf(HCl (aq))]
[1(-488.2) + 1(-20.17)] - [1(-205.98) + 2(-167.15)] = 31.9099999999999 kJ
31.91 kJ     (endothermic)

Entropy Change

[1ΔSf(ZnCl2 (aq)) + 1ΔSf(H2S (g))] - [1ΔSf(ZnS (s sphalerite)) + 2ΔSf(HCl (aq))]
[1(0.859999999999999) + 1(205.77)] - [1(57.74) + 2(56.48)] = 35.93 J/K
35.93 J/K     (increase in entropy)

Free Energy of Reaction (at 298.15 K)

From ΔGf° values:
[1ΔGf(ZnCl2 (aq)) + 1ΔGf(H2S (g))] - [1ΔGf(ZnS (s sphalerite)) + 2ΔGf(HCl (aq))]
[1(-409.6) + 1(-33.05)] - [1(-201.29) + 2(-131.25)] = 21.1399999999999 kJ
21.14 kJ     (nonspontaneous)

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

Equilibrium Constant, K (at 298.15 K)

0.00019779994006
This process is not favorable at 25°C.

Reference(s):

Ebbing, Darrell D. General Chemistry 3rd ed.; Houghton Mifflin Company: Boston, MA, 1990; p 185.

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