Melting point

Definition

The melting point is the temperature at which a solid turns into a liquid under standard atmospheric pressure. It is a specific physical property characteristic of each substance.

5 Must Know Facts For Your Next Test

1. The melting point of a pure substance is a fixed temperature, while that of an impure substance can vary.
2. Melting points are used to identify substances and assess their purity in laboratory settings.
3. At the melting point, the solid and liquid phases coexist in equilibrium.
4. Impurities typically lower the melting point of a substance and broaden its melting range.
5. The melting process requires energy input, known as the heat of fusion.

Review Questions

• What happens to the physical state of a substance at its melting point?
• How do impurities affect the melting point of a substance?
• Why is the melting point important for identifying substances?

Related terms

Heat of Fusion: The amount of energy required to change one mole of a solid into a liquid at its melting point.

Boiling Point:

The temperature at which a liquid turns into vapor under standard atmospheric pressure.

Phase Transition:

A change in the state of matter (solid, liquid, gas) due to changes in temperature or pressure.