Very Short Question and Answers - Homologous Series

A homologous series is a group of organic compounds having the same functional group, similar chemical properties, and each successive member differs by a –CH₂– (methylene) group.

The functional group present in alcohols is the –OH (hydroxyl) group.

The general molecular formula for alkanes is CₙH₂ₙ₊₂.

Consecutive members of a homologous series differ by a –CH₂– (methylene) group.

Boiling point and melting point are two physical properties that show a regular gradation in a homologous series.

Butene comes after propene in the alkene series. Its molecular formula is C₄H₈.

The general formula for carboxylic acids is CₙH₂ₙ₊₁COOH.

The first three members are methanol (CH₃OH), ethanol (C₂H₅OH), and propanol (C₃H₇OH).

Because they all have the same functional group, which determines their chemical reactivity.

The functional group present in alkynes is the triple bond (C≡C) between two carbon atoms.

The first member is methane (CH₄).

As we move from methane (CH₄) to butane (C₄H₁₀) in alkanes, the boiling point increases due to larger molecular size.

The second member is ethanoic acid (CH₃COOH).

Homologous series simplifies the study of organic compounds as their properties and preparation methods are predictable.

All members have similar chemical properties since they share the same functional group.

It refers to systematic naming of compounds in a homologous series, usually by IUPAC rules, that makes identifying compounds easier.

Alkenes have the general formula CₙH₂ₙ.

Methanol (CH₃OH) and ethanol (C₂H₅OH) are consecutive members; they differ by a –CH₂– group.

The molecular formula of propyne is C₃H₄.

The functional group determines the chemical reactivity and similar chemical properties of all members in a homologous series.