Boiling point
Haloalkanes boil higher than their parent alkanes because they are heavier and polar. Three rules cover almost every question.
- For the same alkyl group: .
- For the same halogen: a longer chain boils higher.
- For isomers: more branching means less surface contact and a lower boiling point.
Density
| Compound | Density (g/mL) | Compound | Density (g/mL) |
|---|---|---|---|
| 0.89 | 1.336 | ||
| 1.335 | 1.489 | ||
| 1.747 | 1.595 |
Data: NCERT Class 12 Chemistry.
Solubility
Haloalkanes dissolve very little in water, even though they are polar. Dissolving would need energy to break hydrogen bonds in water, and the new attractions cannot pay it back. They mix well with organic solvents.
Melting points of dihalobenzenes
The three isomers have nearly the same boiling point, but the para isomer melts far higher because its symmetry lets it pack better in the crystal. This was asked in January 2023.