Thermodynamic Properties

Thermodynamic Properties

The property that defines the thermodynamic system like pressure, temperature, etc. is called thermodynamic property. They are state variables ( do not depend on path ).

1. Intensive property :

These properties are the properties which are independent of mass. They are same throughout the given part of the system. For example : Pressure, temperature etc.

2. Extensive property :

These properties are the properties which are dependent on mass. They vary throughout the system.

For example :

Let us take a gas chamber ( with gas molecules obviously). Then, divide the chamber into two. Afterwards , we check the values for the thermodynamic properties of the chamber before and after division. In conclusion, if the properties of the system do not change on division of the chamber, it is intensive property else if the properties of the system change, it is called extensive. 

Note : The ratio of an extensive property to the mass is called specific value of that property. 

For example : If ‘E’ be the total energy , ‘m’ be the mass.

Specific energy = (E/m) 

TO CHECK WHETHER A THERMODYNAMIC PROPERTY OR NOT ?

1. A variable is thermodynamic property, if it has a unique value for each thermodynamic state.

2. A variable is thermodynamic property, if the change in its value is independent of path.

In short, we can say that state functions are thermodynamic property while path functions are not thermodynamic property.

Work is not a thermodynamic property because they are path dependent. 

NOTE : WORK IS NOT ALWAYS PATH VARIABLE

Explanation : The total amount of work done on or by a closed system in an adiabatic process, doesnot depend on process path. It depends only on the initial and final states. Similarly, heat is also not a path function in case of adiabatic process for a closed system.