Extensive quantity
In physics and chemistry, an extensive quantity (also referred to as an extensive variable) is a physical quantity whose value is proportional to the size of the system it describes. In general, this means that such a property can be expressed as the sum of the values for each of the subsystems that compose the entire system.
From the mathematical point of view, F is an extensive quantity if, for all <math>\alpha</math>,
- <math>F\left(\alpha V,\alpha N \right)=\alpha F\left(V,N\right),\,</math>
where V is volume and N is number of particles. Thus, extensive quantities are homogeneous functions (of degree 1) of volume and the number of particles.
Extensive quantities are to be contrasted with intensive quantities, which are intrinsic to particular subsystem and remain constant regardless of size. Dividing one extensive quantity by another will in general give an intensive quantity.
Examples
- Electric charge
- Energy
- Enthalpy
- Entropy
- Heat
- Mass
- Mechanical work
- Momentum
- number of particles
- Volumenl:Extensieve grootheid