Question

a mixture of ethane and pure oxygen is used for welding instead of using a mixture of ethyl and air​

Answer 1

When ethyne is burnt in air incomplete burning takes place and produce sooty flame due to limited supply oxygen present in the air. However, if ethyne is burnt in oxygen, it gives a clean flame with high temperature (3000°C ) due to complete combustion of ethyne. Hence, This oxy-acetylene flame is used for welding and it is not possible to attain such a high temperature with air. Due this reason a mixture of ethyne and air is not used for welding.

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