1. Point and Path functions

2. Objectives To understand Point functions and Path functions
Try to relate the examples
To understand difference between point function and path function

3. Path functions
A Path function is a function whose value depends on the path followed by the thermodynamic process irrespective of the initial and final states of the process.

4. Examples of Path function
Heat and work both are examples of path function

6. Point Functions
A Point function (also known as state function) is a function whose value depends on the final and initial states of the thermodynamic process, irrespective of the path followed by the process.

7. Examples of Point Function
Density, enthalpy, internal energy, entropy are the examples of Point function

8. In the P-V diagram given before we can easily see that for the same initial and final states of the system, work done in all the three process is different.
For process A work done is b2A1a
For process B work done is b2B1a
For process C work done is b2C1a

9. Differences between Point function and Path function

10. Point Function Path Function
Its values are based on the state of the system (i.e. pressure, volume, temperature etc.)
Its values are based on how that particular thermodynamic state is achieved.
No matter by which process the state is obtained, its values will always remain the same.
Different processes to obtain a particular state will give us different values.
Only initial and final states of the process are sufficient
We need to know exact path followed by the process
Its values are independent of the path followed
Its values are dependent on the path followed
It is an exact or perfect differential
It is an inexact or imperfect differential.
Its cyclic integral is always zero
Its cyclic integral may or may not be zero
It is property of the system
It is not the property of the system
Its examples are density, enthalpy, internal energy, entropy etc.
Its examples are Heat, work etc.

11. Thank You