Identify the correct increasing order of boiling points of the given compounds:
Propan-1-ol, butan-1-ol, butan-2-ol, pentan-1-ol
Propan-1-ol, butan-1-ol, butan-2-ol, pentan-1-ol
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- Propan-1-ol < butan-1-ol < butan-2-ol < pentan-1-ol
- Pentan-1-ol < butan-1-ol < butan-2-ol < Propan-1-ol
- Propan-1-ol < butan-2-ol < butan-1-ol < pentan-1-ol
- Butan-1-ol < Butan-2-ol < Propan-1-ol < Pentan-1-ol
The Correct Option is C
Solution and Explanation
The boiling point of alcohols depends on two primary factors: the molar mass (length of the carbon chain) and the extent of molecular branching.
Step 2: Meaning
Boiling point increases with an increase in molar mass due to stronger van der Waals dispersion forces. For isomeric alcohols, branching decreases the boiling point by reducing the effective surface area available for intermolecular contact.
Step 3: Analysis
1. Molar Mass: Propan-1-ol (3 carbons) < Butanols (4 carbons) < Pentan-1-ol (5 carbons). This establishes the extremes.
2. Branching: Butan-1-ol is a straight chain, whereas butan-2-ol is branched. Therefore, butan-2-ol has a lower boiling point than butan-1-ol.
3. Assembling the order: Propan-1-ol < butan-2-ol < butan-1-ol < pentan-1-ol.
Step 4: Conclusion
This logical deduction matches the order provided in option (C).
Final Answer: (C)
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