An organic compound A on heating with concentrated `H_(2)SO_(4)` forms a compound B which on addition of one mole of hydrogen in presence of Ni forms a compounds C. One mole od compound C on combustion form two moles of `CO_(2)` and three moles of `H_(2)O`. Identify the compounds A,B and C write the chemical equation of the reactions involved.

Explanation

(i) Since, compounds C on combustion froms two moles of `CO_(2)` and 3 moles of `H_(2)O`, therefore compound C must contain two carbon atoms and six hydrogen atoms. Thus, compounds C must be ethane `(C_(2)H_(6))`.
`underset("Ethane"(C))(C_(2)H_(6))+underset("Oxygen")(7//2O_(2))overset("Heat")tounderset("Carbon dioxide")(2CO_(2))+underset("Water")(3H_(2)O)`
Hence, A is ethanol `(CH_(3)CH_(2)OH)`.
B is ethene `(CH_(2)=CH_(2))`. , C is ethane `(CH_(3)-CH_(3))`.
(ii) Since, compound C is obtained by addition of 1 mole of `H_(2)` in presence of Ni to compound B, therefore,
B must be ethene `(C_(2)H_(4))`.
`underset("Ethene"(B))(CH_(2)=CH_(2))+H_(2)overset("Ni,heat")tounderset((C))underset("Ethane")(CH_(3))-CH_(3)`
(iii) Since, compounds B is formed by heating compound A with conc. `H_(2)SO_(4)`, therefore,
compound A must be ethanol `(C_(2)H_(5)OH)`.
`underset("Ethanol")(CH_(3)CH_(2)OH)underset(("dehydration"))overset("Conc."H_(2)SO_(4),443)tounderset((B))underset("Ethene")(CH_(2))=CH_(2)+H_(2)O`