Water Removal
Hardchemistry
Azeotropic distillation uses an added component primarily to:
Select the correct option:
Solution
Incorrect! Answer:
Form a lower-boiling azeotrope to remove water
- Definition: An azeotrope is a liquid mixture that boils at a constant temperature and has the same composition in the liquid and vapor phases.
- The Problem: Ethanol and water form an azeotrope at 95.6% ethanol, meaning simple distillation cannot produce absolute (100%) ethanol.
- Azeotropic Distillation: An 'entrainer' (e.g., Benzene) is added.
- New Azeotrope: The entrainer forms a new ternary azeotrope (benzene-water-ethanol) with a lower boiling point.
- Function: This azeotrope distills off first, efficiently removing the water. The remaining benzene is then removed as a binary azeotrope, leaving behind absolute ethanol.
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About This Question
- Subject
- chemistry
- Chapter
- purification techniques
- Topic
- water removal
- Difficulty
- Hard
- Year
- 2025
Solution
Correct Answer:
Form a lower-boiling azeotrope to remove water
- Definition: An azeotrope is a liquid mixture that boils at a constant temperature and has the same composition in the liquid and vapor phases.
- The Problem: Ethanol and water form an azeotrope at 95.6% ethanol, meaning simple distillation cannot produce absolute (100%) ethanol.
- Azeotropic Distillation: An 'entrainer' (e.g., Benzene) is added.
- New Azeotrope: The entrainer forms a new ternary azeotrope (benzene-water-ethanol) with a lower boiling point.
- Function: This azeotrope distills off first, efficiently removing the water. The remaining benzene is then removed as a binary azeotrope, leaving behind absolute ethanol.
This hard difficulty chemistry question is from the chapter purification techniques, covering the topic of water removal. It appeared in the 2025 exam.
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