Question

Which of the following gases is formed on heating ethanol with concentrated \( \mathrm{H_2SO_4} \)?

• A. \( \mathrm{CH_4} \)
• B. \( \mathrm{C_2H_2} \)
• C. \( \mathrm{C_2H_6} \)
• D. \( \mathrm{C_2H_4} \)

Hint:

Heating alcohol with conc. \( \mathrm{H_2SO_4} \) → Dehydration reaction → Alkene formation. Ethanol gives ethene (\( \mathrm{C_2H_4} \)).

Answer 1

The Correct Option is D

Concept: Concentrated sulphuric acid acts as a strong dehydrating agent. When ethanol is heated with concentrated \( \mathrm{H_2SO_4} \), it removes a molecule of water (dehydration reaction).
Step 1: Dehydration of ethanol: \[ \mathrm{C_2H_5OH} \xrightarrow[\text{heat}]{\text{conc. } H_2SO_4} \mathrm{C_2H_4} + \mathrm{H_2O} \]
Step 2: Product formed:

Ethene (\( \mathrm{C_2H_4} \)) is an unsaturated hydrocarbon (alkene).
Thus, the gas formed is ethene.