Methanol, ethanol, propanol, and butanol are all members of the alcohol homologous series. Explain what is meant by a homologous series and describe how the physical and chemical properties of alcohols change as the carbon chain length increases.

A homologous series is a family of compounds that share the same general formula and the same functional group. Each successive member differs by a CH₂ unit (one carbon and two hydrogen atoms). For alcohols the general formula is CₙH₂ₙO and the functional group is –OH.

As the carbon chain length increases:
1. The boiling point rises because the larger molecules have greater London dispersion forces.
2. The solubility in water falls because the increasing non‑polar hydrocarbon chain outweighs the polar –OH group.
3. The chemical behaviour remains essentially the same – all alcohols undergo the same reactions (e.g. oxidation, substitution, esterification) and they all combust to CO₂ and H₂O.

Thus, the series shows systematic changes in physical properties while maintaining similar chemical reactivity.