6.1.9

• carboxylic acids contain functional group -COOH
• Physical properties

  solubility

  small cabroxylic acids, like those in the table above, are very soluble in polar solvents like water

  → this is because hydrogen bonds can be formed between carboxylic acid group + water

  • as the hydrocarbon chain of a carboxylic acid increases in size, the solubility decreases

  → this is because only the polar carboxylic acid group can form hydrogen bonds with water

  therefore as more of the molecule becomes non-polar, the solubility decreases
• Chemical properties

  carboxylic acids are weak acids as they partially ionise in solution releasing H+ ion from the carboxylic acid group, forming a carboxylate ion

  undergoes typical acid reactions
• Reaction with metals

  carboxylic acids will react with metals above hydrogen in the reactivity series to make :

  • hydrogen + a metal salt ; name of salt is generated from acid
• Reaction with metal oxides

  metal oxides react with acids + therefore can be classified as bases

  carboxylic acid will react with metal oxides to make :

  • water + a metal salt
• Reaction with metal hydroxides

  Group 1 metal hydroxides are soluble bases that release OH- (aq)

  carboxylic acids will react with metal oxides to make :

  • water + a metal salt
• Reaction with metal carbonates

  metal carbonates are also bases

  carboxylic acids will react with metal carbonates to make :

  • water, carbon dioxide + a metal salt
  • group 1 metals can also form metal hydrocarbonates where carbonic acid (H2CO3) has had only one proton exchanged for a metal ion to form the metal hydrogencarbonate (MHCO3), forming same products