Arrange the following halocompounds in increasing order of their boiling points.
(A) Chloromethane
(B) Bromomethane
(C) Bromoform
(D) Dibromomethane
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → (A), (B), (D), (C)
Boiling point of haloalkanes increases with increasing molecular mass and polarizability (stronger van der Waals forces).
Given compounds:
- Chloromethane (CH₃Cl) → lowest molar mass → weakest intermolecular forces → lowest b.p.
- Bromomethane (CH₃Br) --Higher mass than CH₃Cl → stronger forces → higher b.p.
- Dibromomethane (CH₂Br₂) --- More Br atoms → higher mass → stronger dispersion forces
- Bromoform (CHBr₃) → Maximum Br atoms → highest mass → strongest forces → highest b.p
So, the increasing order of boiling points is:
Chloromethane < Bromomethane < Dibromomethane < Bromoform