Multiple choice

Using the following data 2CH4 (g) + 3O2 (g) → 2CO (g) + 4H2O (g); ΔG° = -1088 kJ CH4 (g) + 2O2 (g) → CO2 (g) + 2H2O (g); ΔG° = -801 kJ Calculate ΔG° for the reaction 2 CO (g) + O2 (g) → 2CO2 (g)

  1. 1028 KJ

  2. -1028 KJ

  3. 514 KJ
    • 514 KJ

  5. -1889 KJ
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D Correct answer
Explanation

2CH4 (g) + 3O2 (g) → 2CO (g) + 4H2O (g) ΔG° = -1088 kJ  (Eq. 1) CH4 (g) + 2O2 (g) → CO2 (g) + 2H2O (g); ΔG° = -801 kJ     (Eq. 2)

Reversed Eq. 1 2CO (g) + 4H2O (g) →2CH4 (g) + 3O2 (g); ΔG° = -(-1088 kJ) (Eq. 3) 2 x Eq. 2 2CH4 (g) + 4O2 (g) → 2CO2 (g) + 4H2O (g); ΔG° = 2 x (-801 kJ) (Eq. 4) On adding eq. 3 and eq. 4, we get 2CO (g) + O2 (g) → 2CO2 (g); ΔG° = -(-1088 kJ) - 2 x (-801 kJ) = -514 KJ

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