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Manipal MET2013ChemistryThermodynamics (C)

Following method of extracting Zn is based on thermodynamics A: 2 ZnS +3 O ₃ 2 ZnO +2 SO ₂B: ZnO + C Zn + CO If G_f^ (standard free energies of formation, in kJ mol ⁻¹ ) of ZnS =-205.4 , aligned & ZnO =-318.0, SO ₂=-300.4 & CO =-137.3 aligned Free energy changes of the above reaction A and B (respectively) will be

Options

  1. A-826.4 ~kJ ,+180.9 ~kJ
  2. B+826.4 ~kJ ,-180.9 ~kJ
  3. C-826.4 ~kJ ~J ₁-180.9 ~kJ
  4. D+826.4 ~kJ ,+180.9 ~kJ

Correct answer

A. -826.4 ~kJ ,+180.9 ~kJ

Step-by-step solution

For reaction A aligned G^ & =2 G_f^ ( ZnO )+2 G_f^ ( SO ₂ )-2 G_f^ ( ZnS ) & =2[-3182-300.4+205.4] & =-826.4 ~kJ ( G_f^ ( element )=0 ) aligned For reaction B aligned G^ & = G_f^ ( CO )- G_f^ ( ZnO ) & =-137.3+328.2 & =+180.9 ~kJ aligned

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