In the thermodynamics it is very important to know about the terms we use . As we are familiar with some of the terms we discussed earlier in
Some of the terms are discussed below :
Macroscopic and Microscopic Approach :
To study any system it is very necessary to know about the approach of study i.e., on what parameters we are studying the system .
(a)
The average study of the system is known as Macroscopic Approach .
In Classical thermodynamics we use macroscopic approach , where we study about the system on average basis.
The molecular level study of system is known as Microscopic approach.
In statistical thermodynamics , we use Microscopic approach , where we study about the system in molecular basis .
Principal of continuum :
The principal of continnum is said to be satisfied by the system if the system has uniform mass distribution .
The macroscopic approach is valid only when the system satisfy the principal of continuum.
Point Function :
The Thermodynamic functions which depends only on end points of the process are Point functions .
All the thermodynamic properties are point functions because they depends only on end points .
The point functions are also called as State functions .
The point function is exact differential therefore we can write it in a form
dP =P’ – P and dT = T’ – T
And for any cycle ,
Initial point = final point
i.e., P’ = P
Therefore cyclic integral of point function will be zero .
Note :
If a function is a property then it will be point function , and exact differential , then it’s cyclic integral will be zero .
Here are some examples of point function :
Pressure, temperature , volume, entropy , enthalpy , internal energy , etc .
Path Function :
The thermodynamic functions which depends on the whole process are path functions.
As the heat and work are not properties , then these are the path functions.
The path function is inexact differential and it can not be written in following way :
dP = P’ – P ( we can’t write like this in case of path function)
Note :
If a thermodynamic function is not a property , then it will be a path function and inexact differential and therefore it cyclic integral will be zero.
For example :
Heat , work and entropy generation.
