• ThermEvery system has certain characteristics by which its physical conditions may be described which depends upon its state but not upon how the state is reached for example volume, temperature, pressure, etc. Such characteristics are called Properties of the System. These are all macroscopic in nature. When all the properties of a system have definite values the system is said to exist at a definite state. Properties are the coordinates to describe the state of a system. They are state variables.

• There are some other properties of a system which can neither be observed or obtained by mathematical operations of other properties but only can be defined by means of laws of thermodynamics. Two such properties are:

1. Intensive property
2. Extensive property

Intensive Property

• These properties are independent of the mass in the system for example- pressure, temperature, etc.

Extensive Property

• These properties depend on the mass of the system for example- energy, volume, etc. If mass is increased the values of the extensive properties also increase. Extensive properties per unit mass are intensive properties and are called as specific extensive properties for example- specific volume, specific energy, etc.