Carboxylic Acids - Physical Properties
Carboxylic acids
- Carboxylic acid is the name given to the family of compounds that contain the carboxyl functional group, -COOH
- The general formula of a carboxylic acid is CnH2n+1COOH which can be shortened to just RCOOH
- (In some countries, this family is also called alkanoic acid)
- The nomenclature of carboxylic acid follows the pattern alkan + oic acid, e.g. propanoic acid
- There is no need to use numbers in the name as the carboxyl group, COOH, is always on the number 1 carbon atom
Carboxylic Acids Examples Table
Physical properties of carboxylic acids
- Carboxylic acids contain two polarised groups
- C=O and O-H
- This means that the intermolecular forces that carboxylic acids experience are high and they will have relatively high melting points and boiling points
- The presence of the O-H bond means that they can exhibit hydrogen bonding
- Not only does this contribute to the high melting and boiling points, it also contributes to the solubility in water and other polar solvents of the shorter chained carboxylic acids
- However, solubility falls as the length of the hydrocarbon chain in the carboxylic acid increases
- The hydrocarbon chains are forcing their way between water molecules and so breaking hydrogen bonds between those water molecules
- Carboxylic acids with more than eight carbon atoms will be solids at room temperature and are very slightly soluble in cold water, but will be more soluble in hot water
