Question 2:
A mixture of oxygen and ethyne is burnt for welding. Can you tell why a mixture of
ethyne and air is not used?
Answer:
2HC ≡ CH + 5O2 → 4CO2 + 2H2O + Heat
When ethyne is burnt in air, it gives a sooty flame. This is due to incomplete
combustion caused by limited supply of air. However, if ethyne is burnt with oxygen,
it gives a clean flame with temperature 3000°C because of complete combustion.
This oxy-acetylene flame is used for welding. It is not possible to attain such a high
temperature without mixing oxygen. This is the reason why a mixture of ethyne and
air is not used.
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