Arrange the following sets of compounds in order of their increasing boiling points.
A. Pentan-1-ol
B. Butan-1-ol
C. Butan-2-ol
D. Ethanol
E. Propan-1-ol
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 4
The correct answer is option 4. D < E < C < B < A.
The compounds Pentan-l-ol, butan-1-ol, butan-2-ol, ethanol, propan-1-ol belong to the alcohol family. Let us write the structure of these alcohols as shown below:
With increase in the molecular weight, the boiling points of alcohols increase. Hence, butan-1-ol has higher boiling point than propan-1-ol. Similarly, pentan-1-ol has higher boiling point than butan-1-ol. And Propan-1-ol has higher boiling point than ethanol. Hence, the increasing order of the boiling points of alcohols is ethanol < propan-1-ol < butan-1-ol < pentan-1-ol.
With increase in the branching of alkyl groups, the boiling point of alcohols decreases. Thus, butan-2-ol has lower boiling point than butan-1-ol. The increasing order of the boiling points of given alcohols is
ethanol < propan-1-ol < butan-2-ol < butan-1-ol < pentan-1-ol.