Question

Which is longer, the carbon–oxygen single bond in a carboxylic acid or the carbon–oxygen bond in an alcohol? Why?

Short answer

The carbon-oxygen bond in alcohol is longer than the carbon-oxygen single bond in Carboxylic acid.

Step-by-step solution

Step-by-step Solution Step 1: Hybridization

Hybridization is defined as the process of mixing two atomic orbitals to give rise to new type of Hybridized orbitals.This orbital intermixing usually results in formation of hybrid orbitals with entirely different energies and shapes. For example, when 1s and 3p orbitals of the same element mix together, it gives hybrid orbital of sp³hybridization.

Delocalization

In a molecule, when an electric charge is spread over more than one atom, delocalization happens.In chemistry, delocalized electrons are electrons in a molecule or ion that are not associated with a single covalent bond.

Identify the longer C-O bond between alcohol and carboxylic acid

The carbon-oxygen single bond in the case of alcohol is longer than the carbon-oxygen single bond in Carboxylic acid. Higher the percentage of the s-character, shorter is the bond. This can be explained on the basis of hybridization and delocalization as shown below.

The carbon-oxygen single bond in an alcohol is longer because, as a result of electron delocalization, the carbon-oxygen single bond in a carboxylic acid develops some double bond character.