Acids in Solution continued...

The terms strong and concentrated should not be confused. Hydrochloric acid is a strong mineral acid and ethanoic acid is a weak organic acid. The terms concentrated and dilute refer to the amount of water present. So dilute hydrochloric acid is a strong acid and concentrated ethanoic acid is a weak acid.

The Chemical Reactions of Acids

Acids have characteristic reactions with metals, bases and carbonates. Watch each of the video sequences in turn to see these reactions occurring in the laboratory.

Video 1: The reaction between dilute hydrochloric acid and magnesium.

Acids react with metals to produce a salt and hydrogen gas.

For example:

hydrochloric acid + magnesium -> magnesium chloride + hydrogen

The rate of the reaction between metals and acids depends on the reactivity of the metal and the concentration of hydrogen ions in the acid solution. For example, magnesium is a reactive metal so it gives a rapid reaction with dilute hydrochloric acid. Copper, which is at the other end of the reactivity scale, is unreactive so it has no reaction with dilute hydrochloric acid.

Caption: A salt is formed when the hydrogen ion of an acid is replaced by a metal ion. Hydrochloric acid forms salts called chlorides. Sulphuric acid forms salts called sulphates. Nitric acid forms salts called nitrates.

Video 1

Video 2: The reaction between dilute sulphuric acid and copper oxide

Acids react with bases to produce a salt and water.

For example:

sulphuric acid + copper oxide -> copper sulphate + water

Caption: A base is any metal oxide or a metal hydroxide. A base that dissolves in water is called an alkali. The reaction between an acid and a base is called a neutralisation reaction.

Video 2

Video 3: The reaction between dilute nitric acid and calcium carbonate

Acids react with carbonates to produce a salt, carbon dioxide and water.

For example:

nitric acid + calcium carbonate -> calcium nitrate + carbon dioxide + water

This reaction can be used as a test for acids.

Video 3