2 ZnS (s sphalerite) + 3 O2 (g) → 2 ZnO (s) + 2 SO2 (g)

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Stoichiometry

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ZnS            Mass: g
O2             Mass: g  or Gas Volume: L
ZnO            Mass: g
SO2            Mass: g  or Gas Volume: L
Heat Released: kJ

Enthalpy of Reaction

[2ΔHf(ZnO (s)) + 2ΔHf(SO2 (g))] - [2ΔHf(ZnS (s sphalerite)) + 3ΔHf(O2 (g))]
[2(-348.28) + 2(-296.83)] - [2(-205.98) + 3(0)] = -878.26 kJ
-878.26 kJ     (exothermic)

Entropy Change

[2ΔSf(ZnO (s)) + 2ΔSf(SO2 (g))] - [2ΔSf(ZnS (s sphalerite)) + 3ΔSf(O2 (g))]
[2(43.64) + 2(248.11)] - [2(57.74) + 3(205.03)] = -147.07 J/K
-147.07 J/K     (decrease in entropy)

Free Energy of Reaction (at 298.15 K)

From ΔGf° values:
[2ΔGf(ZnO (s)) + 2ΔGf(SO2 (g))] - [2ΔGf(ZnS (s sphalerite)) + 3ΔGf(O2 (g))]
[2(-318.32) + 2(-300.19)] - [2(-201.29) + 3(0)] = -834.44 kJ
-834.44 kJ     (spontaneous)

From ΔG = ΔH - TΔS:
-834.41 kJ     (spontaneous)

Equilibrium Constant, K (at 298.15 K)

1.5692696375e+146
This process is favorable at 25°C.

Reference(s):

Swaddle, T.W. Inorganic Chemistry; Academic Press: San Diego, 1997; p 385.

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