Question

(a) What is a fuel? Give five examples of fuels.
(b) What are the characteristics of an ideal fuel (or good fuel)?
(c) The calorific value and ignition temperature of fuel A are 55 kJ/g and 80°C, respectively. These values for fuel B are 80 kJ/g and 10°C, respectively. On burning, the fuel A produces CO₂ and H₂O while the fuel B produces CO₂ , CO and SO₂. Give three points of relative advantages and disadvantages of these two fuels.

Answer 1

a) Materials that burn to produce heat energy are known as fuels.
Examples of fuels are wood, coal, petrol, diesel and liquefied petroleum gas (LPG).

b) The characteristics of a good fuel are the following.
1. It should have a high calorific value, i.e., it should give an adequate amount of heat per unit mass.
2. It should burn without giving out any harmful gases, so that it does not pollute the air.
3. It should have a proper ignition temperature, so that it burns easily. (Its ignition temperature should neither be too low nor too high.)
4. It should be cheap, easily available and easy to handle.
5. After burning, it should not leave much ash.

c) Advantages of fuel 'A'.
1.It has a moderate ignition temperature.
2. It does not produce any harmful gases.

Disadvantage:
1. It has a low calorific value and produces less heat per unit mass.

Advantage of fuel 'B':
1. It has a high calorific value and hence generates more heat.

Disadvantages:
1. It has a very low ignition temperature and hence is unsafe to use.
2. It produces harmful gases, such as CO and SO_2.