Question

The heat of combustion of ${CH}_4$ and $C_4{H}_{10}$ are $-890.3kJ$ ${mol}^{-1}$ and $2878.7kJ$ ${mol}^{-1}$ respectively. Which of the two has greater efficiency as fuel per gram?

Answer 1

Molar mass of methane $=16$
Heat produced per gram of methane$=-\frac{890.3}{16}=-55.64kJ$
Molar mass of butane$=58$
Heat produced per gram of butane$=-\frac{2878.7}{58}=-49.63kJ$
Thus, methane has greater fuel efficiency than butane.