Molten
Summary: The liquid state of a substance that is normally solid at room temperature, formed by heating it above its melting point. Tags: igcse chemistry keyword Created: 2026-08-06
A substance is described as molten when it is in the liquid state but is normally solid at room temperature — it has been heated above its melting point. For example, sodium chloride is a white solid at room temperature but becomes molten sodium chloride when heated to about 800 °C. In equations, molten compounds are given the state symbol (l).
The key IGCSE exam point is that molten ionic compounds conduct electricity. In the solid state the ions are held in fixed positions in the giant ionic lattice and cannot move, so the solid does not conduct. When heated to melting, the lattice breaks down and the ions become free to move — the mobile ions then carry charge through the liquid. This is why electrolysis of ionic compounds is always carried out on the molten compound (or an aqueous solution of it), never the solid.
Sources
- Cambridge IGCSE Chemistry 0620 Syllabus (2023-2025), Cambridge Assessment International Education
Common Misconceptions
| Misconception | Reality |
|---|---|
| Molten and aqueous mean the same thing | Molten means melted by heating (no water involved); aqueous means dissolved in water |
| Molten means the substance is a gas | Molten is the liquid state formed by heating above the melting point |
| Ionic compounds conduct electricity in all states | They conduct only when molten or dissolved in water, when ions are free to move; the solid does not conduct |