Carboxylic Acids

Carboxylic acids

  • The carboxylic acids form a homologous series. Like all homologous series, the carboxylic acids:
    • have the same general formula
    • differ by CH2 in molecular formulae from neighbouring compounds
    • show a gradual variation in physical properties, such as their boiling points
    • have similar chemical properties

Functional group

  • The functional group in the carboxylic acids is the carboxyl group, –COOH

  • It is responsible for the typical reactions of carboxylic acids, which are weak acids.

    • Vinegar is a dilute solution of ethanoic acid.

General formula

  • The general formula for the carboxylic acids is CnH2n+1COOH (where n is the number of carbon atoms in the molecule, minus 1).
  • Remember that the O atoms are not joined to each other

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Acid properties

  • The carboxylic acids have the typical properties of acids. For example, they:

    • dissolve in water to form acidic solutions with pH values lower than 7
    • react with metals to form a salt and hydrogen
    • react with bases to form a salt and water
    • react with carbonates to form a salt, water and carbon dioxide
  • These properties are due to the –COOH functional group.

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