Question

The calorific values of petrol and CNG are $45000\mathrm{kJ}{\mathrm{kg}}^{-1}$ and $50000\mathrm{kJ}{\mathrm{kg}}^{-1}$, respectively. If you have a vehicle which can run on petrol as well as CNG, which fuel will you prefer and why?

Answer 1

CNG would be preferable:-

• The calorific value of a fuel can be defined as the amount of heat produced during the complete combustion of a given amount of substance at STP.
• This calorific value is directly proportional to the efficiency of the fuel.
• That is more the calorific value is more will be the efficiency of the fuel.
• So from the above data, we can see that the calorific value of CNG is $50000\mathrm{kJ}{\mathrm{kg}}^{-1}$ which is more than the calorific value of petrol which is $45000\mathrm{kJ}{\mathrm{kg}}^{-1}$.
• Thus the efficiency of the CNG gas would be better than that of petrol.
• Also, the CNG would produce less pollution than petrol and is more economical as well.

Therefore, CNG would be preferable.