Intensive and Extensive Properties of Matter

Intensive and Extensive Properties

Intensive Properties

Intensive properties are physical properties of matter that do not depend on the amount of substance present. These properties are useful for identifying substances because they remain constant regardless of sample size.

• Definition: Properties that are independent of the size or amount of substance present.

• Examples:

  • Color

  • Density

  • Hardness

  • Melting Point

  • Luster

  • Temperature

• Application: Intensive properties are used to characterize and identify materials.

Example: Melting point and luster are intensive properties, while mass and volume are not.

Extensive Properties

Extensive properties are physical properties that depend on the amount of substance present. These properties change when the size of the sample changes.

• Definition: Properties that are dependent on the size or amount of substance present.

• Examples:

  • Mass

  • Length

  • Volume

  • All forms of energy (e.g., chemical energy, Gibbs free energy)

• Application: Extensive properties are useful for measuring the quantity of material present.

Example: Chemical energy is an extensive property, while electrical conductivity, luster, and freezing point are not.

Comparison Table: Intensive vs. Extensive Properties

Intensive Properties	Extensive Properties
Color	Mass
Density	Length
Hardness	Volume
Melting Point	All forms of energy
Luster	Chemical energy

Key Points

• Physical properties can be classified as either intensive or extensive.

• Intensive properties are useful for identifying substances, while extensive properties are useful for measuring quantities.

Practice Questions

• Which of the following is not an example of an intensive property?

  • Elemental magnesium (Correct answer: This is a substance, not a property)

  • Density

  • Temperature

  • Melting point

  • Freezing point

• Which of the following is an extensive property?

  • Mass

  • Gibbs free energy

  • Volume

  • All forms of energy

Additional info: Intensive and extensive properties are foundational concepts in chemistry, helping students distinguish between characteristics that are inherent to a material and those that depend on sample size. This distinction is crucial for laboratory measurements and chemical identification.