# Salts

Show/Hide Sub-topics (Acids, Bases & Salts | O Level)

A salt is an ionic compound formed when the hydrogen atom in an acid is replaced by a metal ion or ammonium ion.

• Note: Please do not restrict your thinking/interpretation of “salt” to the normal “table salt” in your kitchen.
• Neutralization is one common reaction whereby a salt is produced.

An acid reacts with a base (neutralization reaction) to produce a salt and water.

• The salt consists of two parts – one part is from the acid, while the other is from the base.
• E.g. $\text{KOH} + \text{HCl} \rightarrow \text{KCl} + \text{H}_{2}\text{O}$
• The potassium part of the salt (potassium chloride – $\text{KCl}$) is from the base and the chloride part is from the acid.

The table below shows the solubility of the different types of salts in water. (IMPORTANT!)

Type of salt Soluble In Water Exceptions
Ammonium Salts Yes
Nitrate Salts Yes
Ethanoate Salts Yes
Alkali metal (Group I) Salts Yes
Chloride Salts Yes

(With some exceptions)

Silver chloride

Mercury chloride

Sulphate Salts Yes

(With some exceptions)

Calcium sulphate

Barium sulphate

Carbonate Salts No

(With some exceptions)

Alkali metal carbonates (e.g. sodium carbonate)

Ammonium carbonate

(With some exceptions)

### Preparation of Salts

The most efficient way of preparing salts is the way whereby the salt can be easily extracted without loss of yield.

The table below shows the overview of the different preparation methods. We will go into the details in the next post.

Salt Prepared Preparation Method Extraction Method Examples
Soluble Solution + excess solid Filter any excess solid

Evaporate the filtrate

Acid + metal

Acid + carbonate(s)

Acid + base(s)

Soluble Solution + solution

(via titration)

Evaporate Acid + alkali(aq)

Acid + carbonate(aq)

Insoluble Solution + solution Filter out precipitate Solution + solution