Question

An organic compound X on heating with conc. H2SO4 forms a compound Y which on addition of one molecule of hydrogen in the presence of nickel forms a compound Z. One molecule of compound Z on combustion forms two molecules of CO2 and three molecules ofH2O. Identity giving reasons the compounds X, Y, Z.W rite the chemical equations for all the chemical reactions involved.

Answer 1

As given the compound X forms compound Y on reaction with H2SO4.

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

Also, compound Z 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 Z 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

Answer 2

We are given that the compound B on addition of one mole of H2 in the presence of Ni forms another compound. This suggests that the compound B is unsaturated. Since the compound B is formed by dehydration of compound A by using H2SO4, it means that compound A is an alcohol. Compound C will be alkane (alkenes on hydrogenation give alkanes). As compound C gives two molecules of CO2 and three molecules of H2O, it means that it is an alkane containing two carbon atoms. Thus

Compound A = CH3CH2OH

Compound B = CH2=CH2

Compound C = CH3-CH3

Following are the chemical equations for the reactions