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30/09/2021 3:17 pm
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The factor of ΔG values is important in metallurgy. The ΔG values for the following reactions at 800ºC are given as:
S2(s) + 2O2(g) → 2SO2(g); ΔG = -544 kJ
2Zn(s) + S2(g) → 2ZnS(s); ΔG = -293 kJ
2Zn(s) + O2(g) → 2ZnO(s); ΔG = -480 kJ
Then ΔG for the reaction :
2ZnS(s) + 3O2(g) → 2ZnO(s) + 2SO2(g)
will be:
(a) -357 kJ
(b) -731 kJ
(c) -773 kJ
(d) -229 kJ
1 Answer
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30/09/2021 3:24 pm
Correct answer: (b) -731 kJ
Explanation:
For the reaction
2ZnS(s) → 2Zn + S2(g); ΔG°1 = -293 kJ .....(i)
2Zn(s) + O2(g) → 2ZnO(s); ΔG°2 = -480 kJ .....(ii)
S2(s) + 2O2(g) → 2SO2(g); ΔG°3 = -544 kJ ......(iii)
ΔG° for the reaction
2ZnS + 3O2(g) → 2ZnO(s) + 2SO2
can be obtained by adding eqn. (i), (ii) and (iii)
⇒ ΔG° = 293 - 480 - 544
= - 731 kJ