Preparation of Salts

Preparation of Soluble Salts

Any soluble salt can be made by reacting a suitable insoluble base (such as a metal oxide, metal hydroxide or metal carbonate) with an acid.
Alternatively, a salt can also be made by neutralising a solution of an acid by adding an alkali to it (such as a soluble hydroxide or carbonate).
A chemical reaction usually occurs, producing the salt and water.
The type of acid used will determine the non-metal part of the salt’s name, for example, sulfuric acid will produce a sulfate salt, hydrochloric acid a chloride salt and nitric acid a nitrate salt.

Preparation of Insoluble Salts

Insoluble salts are made by mixing two solutions to form a precipitate.
This is often done by mixing solutions of two soluble salts.
This process is known as precipitation.
The resulting mixture can then be filtered to obtain the precipitate.

Specific Salts

Copper sulfate: This blue salt can be made by reacting copper oxide or copper carbonate with sulfuric acid.
Sodium chloride: This common salt can be made by neutralising hydrochloric acid with sodium hydroxide solution.
Iron(III) oxide: This red-brown solid can be made by precipitating iron(III) sulfate solution with sodium hydroxide solution.
Barium sulfate: This white solid is made by precipitating barium chloride solution with sulfuric acid.

Note: Reacting solutions of barium chloride and sodium sulfate will also produce insoluble barium sulfate, and this is a good way to test for sulfate ions in a solution. If a white precipitate forms when barium chloride solution is added to a solution, the original solution likely contains sulfate ions.

Important Safety Considerations

Always wear protective eyewear and gloves when handling acids and alkalis.
Never add water to acid, always add—carefully—acid to water.
Dispose of acids, alkalis, and neutralisation products according to safe disposal procedures.