Using the data below, decide which combustion reaction releases more energy per gram of oxygen consumed:

1) C(s) + O₂(g) → CO₂(g) ΔH_f°(CO₂) = -393.5 kJ mol⁻¹, C=O bond energy = 799 kJ mol⁻¹

2) S(s) + O₂(g) → SO₂(g) ΔH_f°(SO₂) = -296.8 kJ mol⁻¹, S=O bond energy = 523 kJ mol⁻¹

The O=O bond energy is 498 kJ mol⁻¹. State which element (C or S) gives the larger energy release per gram of O₂.

Question

Using the data below, decide which combustion reaction releases more energy per gram of oxygen consumed:

1) C(s) + O₂(g) → CO₂(g) ΔH_f°(CO₂) = -393.5 kJ mol⁻¹, C=O bond energy = 799 kJ mol⁻¹

2) S(s) + O₂(g) → SO₂(g) ΔH_f°(SO₂) = -296.8 kJ mol⁻¹, S=O bond energy = 523 kJ mol⁻¹

The O=O bond energy is 498 kJ mol⁻¹. State which element (C or S) gives the larger energy release per gram of O₂.

Accepted Answer

Carbon (C) releases more energy per gram of O₂

Waec Model Questions Vol1 2019 Chemistry Question 37