Q 4. Answer the following questions:.
1. Draw the diagram of candle flame and label it.
2. Compare LPG and Wood as fuels.
3. List conditions under which combustion takes place. Explain any one of them.
4. In an experiment 5Kg of fuel was completely burnt. The heat produced was measured to be 2,00,000 KJ. Calculate the calorific value of the fuel
Answers
Answer 2.
LPG :-
1. It has more calorific value about 55000 kJ/kg.
2. It does not cause any environmental problem.
3. It is smokeless fuel.
4. It is easy to store.
5. It can be easily transported.
6. Low Ignition temperature.
Wood :-
1. It has less calorific value about 17000 to 22000 kJ/kg.
2. On burning wood release unburnt carbon particles which causes asthma.
3. It gives out lot of smoke.
4. It needs a lot of space for storage.
5. It cannot be easily transported.
6. High Ignition temperature
Answer 3.
The conditions required for combustion to take place are:
1. Presence of a fuel
2. Air (or oxygen)
3. Ignition temperature (minimum temperature at which a substance catches fire).
Answer 4.
Total mass of fuel =5kg
Total heat produced=2,00,000KJ
Heat produced by burning 1kg of fuel = 2,00,000/5kg = 40,000 KJ/kg.
So, Calorific value of fuel= 40,000 KJ/kg.
4answer:
Calorific value = energy produced ÷mass of fuel
I.e.2,00,000 ÷ 5 = 40,000kj/kg
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