Edexcel A Level Chemistry:复习笔记7.3.1 Physical Properties of Carboxylic Acids

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