Question

The calorific value of a fuel whose 1.5 kg of mass produces 67,500 kJ of heat on burning completely will be
1. 45,000 kJ/kg
2. 30,000 kJ/kg
3. 1,01,250 kJ/kg
4. 1,01,250 kg/J

Answer 1

Correct Answer - Option 1 : 45,000 kJ/kg

Explanation:

Fuel:  The sources of energy for domestic and industrial purposes are mainly wood, charcoal, petrol, kerosene, etc. These substances are called fuels.

• A good fuel is one which is readily available, cheap, burns easily in the air at a moderate rate, and produces a large amount of heat.
• The efficiency of the fuel is measured by its calorific value
• Calorific Value: The amount of heat energy produced on complete combustion of 1 kg of a fuel is called its calorific value. The calorific value of a fuel is expressed in a unit called kilojoule per kg (kJ/kg).

Calculation:

Total mass of fuel = 5 kg
Heat produced by burning the given mass of fuel = 67,500 kJ
We know that calorific value of fuel =Heat Produced /Mass Burnt =67,500 kJ / 1.5 Kg.
Hence, the calorific value of the given fuel = 45,000 kJ/kg

• Given the table shows the calorific value of some fuels:

Fuel	Calorific Value (kJ/kg)
Cow dung cake	6000 - 8000
Wood	17,000 - 22,000
Coal	25,000 - 33,000
Petrol	45,000
Kerosene	45,000
Deisel	45,000
Methane	50,000
CNG	50,000
LPG	55,000
Biogas	35,000 - 40,000
Hydrogen	1,50,000