Salts: What is a salt?

4.0 Salts

4.1 What is a salt?

Salt is a familiar concept. Let us share what we know about salt.

Questions 4.1a

1. Common salt is an example of salts. What is the chemical name of common salt?
2. What are the two elements combined in common salt?

Study Table 4.1 which shows other examples of salt and common acids, and use it to answer Questions 3, 4 and 5.


Table 4.1: Some common examples of salts and acids.



3. What have you noticed as a main difference between salts and acids?
4. How can we obtain a salt from an acid?
5. Define a salt.

All acids have hydrogen ions (H⁺). That is what makes them acids. When some or all the hydrogen ions are replaced by a metal, we obtain a salt. A salt is a substance obtained when some or all hydrogen ions in an acid are replaced by metallic ions. Metallic ions include Na⁺, K⁺, Mg²⁺, Ca²⁺, Al³⁺, Zn²⁺, Cu²⁺, Pb²⁺, NH₄⁺, and so on. Any metal combined with non-metals, excluding oxides and hydroxides, is a salt.

Questions 4.1b

Identify salts from the following list of substances.
AgOH, Na₂S, Cu₂S, ZnI₂, CaO, PbBr₂, Na₂CO₃, Zn(OH)₂, AgNO₃, FeBr₃, LiCl, Na₃PO₄, CaHPO₄, (NH₄)₂HPO₄, MnO₂, Ca₃PO₄, Na₂SO₃, Na₂PO₃