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
Lead(II) chloride Mercury chloride |
| Sulphate Salts | Yes
(With some exceptions) |
Calcium sulphate
Lead(II) sulphate Barium sulphate |
| Carbonate Salts | No
(With some exceptions) |
Alkali metal carbonates (e.g. sodium carbonate)
Ammonium carbonate |
| Lead Salts | No
(With some exceptions) |
Lead(II) nitrate
Lead(II) ethanoate |
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 |
