Question

A compound X on heating with excess conc. sulphuric acid at 443K gives an unsaturated compound Y. X also reacts with sodium metal to evolve a colourless gas Z. Identify X,Y and Z. Write the equation of the chemical reaction of formation of Y and also write the role of sulphuric acid in the reaction.

Answer 1

X →443 Kconc. H2SO4 Y ( unsaturated compound)
Z is hydrogen (Colourless gas) 

X, Y and Z are alcohol, alkene and hydrogen respectively.

Suppose X is ethanol,it gives alkene on reacting with conc. H2SO4

 C2H5OH (X) →443 Kconc. H2SO4  C2H4 (Y)

2C2H5OH →Na2C2H5O-Na+ + H2 (Z)

Role of sulphuric acid: It is used as a dehydrating agent in the above reaction.

Answer 2

X - Ethanol
Y - Ethene
Z - Hydrogen gas

C₂H₅OH ----in presence of hot.concentrated H₂SO₄ and heating at 443 K  ----------→ CH₂ = CH₂ + H₂O

Here, sulphuric acid behaves as a dehydrating agent which removes the water from ethanol to form ethene.