Question

Arrange the following in increasing order of their boiling points:
1-chloropropane, 2-chloropropane, 1-chlorobutane 
(A) 2-chloropropane $<$ 1-chloropropane $<$ 1-chlorobutane

Hint:

Boiling point increases with molecular mass and decreases with branching.

Answer 1

Step 1: Boiling point depends on molecular weight, surface area, and branching.
Step 2: Among the three compounds:

• 2-chloropropane is more branched, hence has lower surface area and lower boiling point.
• 1-chloropropane is linear and less branched, so it has a higher boiling point than 2-chloropropane.
• 1-chlorobutane has a larger molecular size and greater surface area than both propyl compounds, hence the highest boiling point.

\[ \text{Order: } 2\text{-chloropropane}<1\text{-chloropropane}<1\text{-chlorobutane} \]