Carboxylic acids

Question 1

Name some things that have carboxylic acid.

Answer 1

• The sting of ants contains methanoic acid.
• Vinegar contains ethanoic acid.
• The smell of goats is caused by hexanoic acid.

Question 2

Discuss the solubility of carboxylic acids.

Answer 2

• Carboxylic acids with between one and four carbon atoms are very soluble in water. The highly polar C=O and O-H bonds allow carboxylic acid molecules to form hydrogen bonds with water molecules. As the number of carbon atoms in the carboxylic acids increases, the solubility decreases. This is the results of the longer non-polar hydrocarbon chain in the molecule, which does not interact with water molecules.

Question 3

Are carboxylic acids strong/weak acids?

Answer 3

Carboxylic acids are weak acids when compared with nitric, sulfuric and hydrochloric acids.

Carboxylic acids take part in the typical acid reactions - reacting with metals, carbonates and bases to form salts.

Question 4

What are carboxylates?

Answer 4

Salts formed from carboxylic acids are known as carboxylates.

A carboxylate ion is like a carboxylic acid with the H on OH group missing, hence leaving a negatively charged O, oxygen.

Question 5

What do carboxylic acids form when:

• reacting with metals
• reacting with bases
• reacting with carbonates

Answer 5

• A carboxylic acid reacts with reactive metals to form a salt and hydrogen gas.
• Carboxylic acids react with aqueous bases, such as metal hydroxides, to form a salt and water.
• An aqueous solution of a carboxylic acid reacts with carbonates to form a salt, carbon dioxide and water.