Question

Give an example of the following
A carbon compound which burns with a sooty flame.

Answer 1

Hint:The Unsaturated carbon compounds actually burn with a sooty flame. Such flame has yellow color and is polluting also.Unsaturated hydrocarbons are hydrocarbons that have double or triple covalent bonds between adjacent carbon atoms. The term "unsaturated" means more hydrogen atoms may be added to the hydrocarbon to make it saturated (i.e. consisting of all single bonds).

Complete step by step answer:
Unsaturated hydrocarbons are generally those that consist of double or triple bonds between the adjacent carbon atoms.
Now, as unsaturated carbon compounds contain double or triple bonds these bonds are far more stronger than the single bonds due to which these bonds don’t break easily and tend to produce a yellow or sooty flame.
Sooty flame is the flame that contains carbon content due to incomplete combustion of the compound. It is of yellow color & due to the presence of carbon content in it, it is polluting also.
Unsaturated compounds like ethyne, acetylene and many more compound burns to give yellow sooty flame.
One reason can be that the carbon content in these compounds is more than alkanes so that’s why they don’t get completely oxidized in air.

Additional information:
For Example, when the air holes of the burner are completely open, LPG that is a mixture of Propane and Butane burns with a Blue-non sooty flame. But what if we close the air holes, now it will burn with a yellow, sooty flame. This is because of incomplete combustion due to partial presence of oxygen. Same happens in the case of unsaturated carbon compounds.


Note:
Unsaturated carbon compounds do not burn completely and give a flame with unburnt or partially burnt carbon particles. Such a flame has yellow color and is polluting. It is called sooty flame. While saturated carbon compounds usually burn completely and give a clear blue flame. This is called non sooty flame.The Sooty Flame is the result of incomplete combustion of the carbon compounds. This is in the case of unsaturated carbon compounds.