Properties of carboxylic acids

What are carboxylic acids?

Organic acids which contain the carboxyl functional group - COOH

• A carboxyl group contains both a carbonyl group and a hydroxyl group

How is a carboxylic acid named?

Adding the suffix -oic acid to the stem of the longest carbon chain

Describe the solubility of carboxylic acids

The C=O and O-H bonds in carboxylic acids are polar, allowing carboxylic acids to form hydrogen bonds with water molecules

• Carboxylic acids with up to four carbon atoms are soluble in water

• As the number of carbon atoms increases, the solubility decreases as the non-polar carbon chain has a greater effect on the overall polarity of the molecule

Describe thee strength of carboxylic acids

Carboxylic acids are weak acids which partially dissociate / ionise

In which reactions do carboxylic acids form salts

• Redox reactions with metals

  • Neutralisation reactions with bases (alkalis, metal oxides, carbonates)

Describe the salts formed by carboxylic acids as well as how they are named

• Carboxylic acids form carboxylate salts

• The carboxylate ion in the salt is named by changing the ‘-ic acid’ to ‘ate’

Carboxylic acid + metal

Carboxylic acid + metal → salt + hydrogen

Write the symbol equation for the reaction of propanoic acid with magnesium?

Carboxylic acid + metal oxide

Carboxylic acid + metal oxide → salt + water

Carboxylic acid + alkali

Carboxylic acid + alkali → salt + water

Carboxylic acid + carbonates

Carboxylic acid + carbonates → carbon dioxide + salt + water

How are carboxylic acids distinguished from phenols?

Neutralisation of the carboxylic acid with carbonates - phenols are not acidic enough to react with carbonates