Extensive Property of a Thermodynamics System

An extensive property of a thermodynamics system is a property that depends on the size or amount of the system. In other words, an extensive property increases or decreases in proportion to the size of the system. Examples of extensive properties include volume, mass, energy, and entropy.

Volume as an Extensive Property

Volume is an extensive property because it depends on the size of the system. For example, if we have two identical containers of water, one with a volume of 1 liter and the other with a volume of 2 liters, the larger container has twice the volume of the smaller one. Similarly, if we add more water to a container, the volume of the container increases proportionally.

The Extensive Property Equation

The extensive property equation is used to relate an extensive property to the size of the system. The equation is:

E = ne

where E is the extensive property, n is the amount of substance in the system, and e is the specific property (i.e. the property per unit amount of substance).

For example, the volume V of a gas is an extensive property, and its specific volume v is the volume per unit mass. Therefore, the extensive property equation for volume is:

V = nV

where n is the number of moles of the gas and V is the molar volume.

Conclusion

In conclusion, an extensive property of a thermodynamics system is a property that depends on the size or amount of the system. Volume is an example of an extensive property because it increases or decreases in proportion to the size of the system. The extensive property equation is used to relate an extensive property to the size of the system.