Question

What happens when ethanol is heated with excess concentrated sulphuric acid at 443 K? Write chemical equation involved. What is the role of concentrated sulphuric acid in this reaction?

Hint:

Conc. H$_2$SO$_4$ at 443 K → Dehydration of ethanol to ethene.

Answer 1

Reaction of Ethanol with Excess Concentrated Sulphuric Acid at 443 K:

When ethanol (C₂H₅OH) is heated with excess concentrated sulphuric acid (H₂SO₄) at 443 K, it undergoes a dehydration reaction and forms ethene (C₂H₄).

In this reaction, a molecule of water is removed from ethanol, resulting in the formation of an unsaturated hydrocarbon (alkene).

Chemical Equation:
C₂H₅OH     → (conc. H₂SO₄, 443 K) C₂H₄ + H₂O

Observation:
A colorless gas (ethene) is produced. Ethene burns with a luminous flame due to the presence of double bonds.

Role of Concentrated Sulphuric Acid:

1. Dehydrating Agent:
Concentrated H₂SO₄ removes water (H₂O) from ethanol.

2. Catalyst:
It speeds up the reaction without being consumed in the process.

Conclusion:
When ethanol is heated with excess concentrated sulphuric acid at 443 K, it forms ethene and water through a dehydration reaction. In this reaction, concentrated sulphuric acid acts as a dehydrating agent and catalyst.