Question

A carbon compound 'P' on heating with conc. H2SO4 forms another carbon compound 'Q' which on addition of hydrogen in the presence of nickel catalyst forms a saturated carbon compound 'R' on combustion forms two molecules of carbon dioxide and three molecules of water. Identify P, Q and R and write chemical equation for the reactions involved.

Answer 1

As given the compound P forms compound Q on reaction with H2SO4. 

and Q is undergoes addition reaction when gets in touch with hydrogen in the presence of Nickel. This make Q a unsaturated compund. 

Also, compound R undergoes combustion and forms two molecules of CO₂ and 3 molecules of H₂O. This is the same thing that ethene do. 

So the reaction is: C₂H₆ + 2O₂ → 2CO₂ + 3H₂O So, this makes R an ethane. 

Ethane is formed on hydrogenation of ethene with one molecule of hydrogen in the presence of nickel.  C₂H₄ + H₂→C₂H₆ and finally Ethanol on dehydration with H₂SO₄ forms ethene