Calorific value of ethane, in kJ/g if for the reaction

$2{\text{C}}_2{\text{H}}_6+7{\text{O}}_2\to 4{\text{CO}}_2+6{\text{H}}_2\text{O};\text{ΔH}=-745.6\text{kcal}$

In the reaction, 2 moles of ethane yielded

– 745.6 kcal

i.e., 2 × molar mass of C₂H₆ = 60 g

$\therefore$60 g yields – 745.6 kcal

Hence, calorific value of ethane is – 52.2 kJ g^–1