Question 1 what is a flame?
Question 2 What type of substances, on burning give a flame?
Question 3 Name few substances which produces flame?
Question 4 What happen when magnesium ribbon is burnt?
Question 5 Charcoal does not burn by producing a flame.Why?
Question 6 How luminous flame is produced?
Question 7 How non-luminous flame is produced?
Question 8 Why LPG stoves gives blue flame?
Question 9 what is the difference between burning of a candle and burning of fuel like coal?
A flame is a region where combustion or burning of gaseous substances take place.
All the gases which undergoes combustion produces flame.But only those solids and liquid fuels which vaporise on being heated,burn with the flame.
Some of the substances which burn by producing flames are LPG, CNG, biogas, wax, camphor, magnesium, kerosene oil, mustard oil.
If we heat magnesium ribbon over a burner,we find that the magnesium ribbon burns by producing a brilliant white flame.
Wax candle and kerosene oil lamp have wicks.Molten wax and kerosene oil rise through the wick,get vaporised during burning and form flames.
Charcoal is a solid fuel which does not vaporise on heating.So,charcoal does not burn by producing a flame.Coal is a solid fuel which does not vaporise on heating.So,coal also does not burn by producing a flame.Coal just glow red on combustion.
1)When the oxygen supply or air supply is insufficient,then the fuels burn incompletely producing mainly a yellow flame.The yellow flame is caused by the glow of hot unburnt carbon particles produced due to incomplete combustion of fuel.This yellow flame produces light,so it is said to be luminous flame.
When kerosene is burned in a lamp,it also burns with a yellow flame.
2)When the oxygen supply or air supply is sufficient,then the fuels burn completely producing mainly a blue flame. This blue flame does not produce much light,so it is said to be non-luminous flame.
In LPG stove,the LPG burns with a blue flame.The design of the burner of kitchen gas stove is such that it provides sufficient air for the complete combustion of LPG.