# Important terms in Thermodynamics :

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.

(b)

#### 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.