91Ó°ÊÓ

The boiling point of compounds is dependent on the molecular weight, intermolecular attractive forces and family of a compound from which it belongs.With an increase in molar mass, the boiling point increases and the more the hydrogen bonding, the higher the boiling point.

• The given isomers are n-pentanol, ethyl acetate and valeric acid. These have different functional groups.
• The carboxylic acid group (-COOH) is present in valeric acid.
• In n-pentanol, the alcohol group (-OH) is present.
• In ethyl acetate, the ester group (-COO) is present.

The boiling point for ethyl acetate (ester-containing compound) is the lowest (77⁰C) because ester does not form hydrogen bonds. Then comes n-pentanol (alcohol-containing compound), which forms hydrogen bonds, so it has a higher boiling point (138⁰C) than ethyl acetate. At last, valeric acid (carboxylic acid-containing compound) forms two hydrogen bonds and boils in the form of a dimer. So, it has the highest boiling point among all (186⁰C)). Thus, the order of increasing boiling point is,

Order of increasing boiling point