# A mixture of oxygen and ethyne is burnt for welding.

Question.
A mixture of oxygen and ethyne is burnt for welding. Can you tell why a mixture of ethyne and air is not used?

solution:
Ethyne is an unsaturated hydrocarbon, therefore, combustion of ethane in air produces a yellow flame with black smoke due to the presence of unburnt carbon in it. Due to this incomplete combustion heat produced is also low and a high temperature usually needed for welding cannot be attained. That is why mixture of ethyne & oxygen is used :

$2 \mathrm{HC} \equiv \mathrm{CH}+5 \mathrm{O}_{2} \longrightarrow 4 \mathrm{CO}_{2}+2 \mathrm{H}_{2} \mathrm{O}+$ heat and Ethyne oxygen light