Question

A mixture of ethyne and oxygen is used for welding. can you justify why a mixture of ethyne and air is not-used?

Answer 1

When ethyne is burnt in oxygen, a large quantity of heat along with light is produced. The heat evolved can be used for gas welding which is usually carried to weld small broken pieces of articles made up of iron.

C2H2(g)+5/2O2(g). gives rise to 2CO2(g)+H2O(l)+ heat and light.

Air mainly contains a mixture of nitrogen 4 parts and oxygen 1 part. Aswer know, nitrogen gas does not support combustion. This means that in air , only oxygen will help in the combustion of ethyne. Therefore, it is always better to use oxygen for the combustion of ethyne to facilitate complete combustion

Hope this helps you

Answer 2

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Air contains nitrogen and other inactive gaseous contents and sufficient oxygen is not available for burning ethyne to give the required heat and incomplete combustion will take place whereas ethyne with oxygen gives enough heat that can be used for welding .