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Extensive Properties

The physical properties of an object or substance are measurable properties. These are the properties that have a value when measured. The change in the physical properties of a system can be termed as a change in the status of that particular object. Some examples of physical properties are- Temperature, Density, weight, mass, volume, etc.

An extensive property is a physical quantity whose value is proportional to the size of the system, or to the quantity of matter in the system. For example, the mass of a sample is an extensive quantity as it depends on the amount of substance. Some examples of Extensive properties are Volume, Enthalpy, Entropy, Mass, Energy, Number of moles etc.

An intensive property is a physical quantity whose value does not depend on the amount of the substance. For example, the temperature of a system in thermal equilibrium is the same as the temperature of any part of it. Some examples of Intensive properties are Molar volume, Pressure, Temperature, Boiling point, Freezing point, Density, Vapour pressure, Refractive index etc.

Types of Physical Property

There are two types of physical properties.

  1. Intensive Property
  2. Extensive Property

 Extensive properties

  • Property whose value depends on the quantity of matter in the system is called extensive property
  • Extensive property depends on the size of the system
  • Properties such as Mass, Volume, Area, Energy, Heat capacity etc., are extensive properties

Intensive Properties

  • A property whose value depends on the nature of the substance, and is independent of its amount in the system is called an intensive property
  • The intensive property does not depend on the size of the system
  • Properties such as Density, Temperature, Pressure, Concentration, Viscosity, Refractive index, Surface tension etc., are some intensive properties

Difference between Extensive and Intensive properties

Extensive properties:

  • Dependent on the amount of matter
  • Not observed easily
  • Non-identifiable
  • Helpful for describing samples
  • Change in the nature of substance

Intensive properties:

  • Amount independent
  • Observed easily
  • Identifiable
  • Helpful for identifying samples
  • Change in the physical behaviour of the substance

Extensive properties vary with the amount of matter, and intensive properties do not. Thus, extensive properties help us define how much matter we have. For example, mass, volume, and the number of moles are all extensive properties. 

Composite Property

The ratio of two extensive properties is an intensive property, and that is called the composite property. For example, mass and volume are two extensive properties. The ratio of mass and volume is the density which is an intensive property. The composite property is sometimes classified as intensive or extensive property.

Specific Property

Specific property is an intensive property obtained by dividing an extensive property by mass. For example, heat capacity is an extensive property. When heat capacity is divided by mass, we get a specific heat capacity which is an intensive property.

Conclusion

The mass of an object is a measure of the amount of matter that an object contains. A small sample of a certain type of matter will have a small mass, while a larger sample will have a greater mass. Another extensive property is volume. The volume of an object is a measure of the space that is occupied by that object.