| Series | General Formula | Example (n=3) |
|---|---|---|
| Alkanes | CₙH₂ₙ₊₂ | Propane (C₃H₈) |
| Alkenes | CₙH₂ₙ | Propene (C₃H₆) |
| Alcohols | CₙH₂ₙ₊₁OH | Propan-1-ol (C₃H₇OH) |
| Carboxylic acids | CₙH₂ₙ₊₁COOH | Propanoic acid |
Properties of a Homologous Series
- Same general formula
- Same functional group → same chemical properties
- Differ by –CH₂– between consecutive members
- Gradual trend in physical properties (e.g. Boiling point increases with chain length due to stronger London dispersion forces)
🔑 Why BP Increases
More –CH₂– units → longer chain → more electrons → larger temporary dipoles → stronger LDFs → more energy needed to separate molecules → higher boiling point.