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Difference Between State Function and Path Function for JEE Main 2024

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Last updated date: 23rd May 2024
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What is State Function and Path Function: Introduction

To differentiate between state function and path function: State functions and path functions are important concepts used to describe the behavior of systems. A state function is a property that depends only on the current state of the system, such as temperature, pressure, volume, or internal energy. It does not rely on the path taken to reach that state. On the other hand, a path function depends on the specific path or process taken to reach a particular state, and it includes quantities like work and heat. Path functions are not solely determined by the initial and final states but are influenced by the specific conditions and steps followed during the process. Read further for more. 


Category:

JEE Main Difference Between

Content-Type:

Text, Images, Videos and PDF

Exam:

JEE Main

Topic Name:

Difference Between State Function and Path Function

Academic Session:

2024

Medium:

English Medium

Subject:

Physics

Available Material:

Chapter-wise Difference Between Topics


Defining State Function 

A state function is a property that depends solely on the current state of a system and is independent of the path taken to reach that state. State functions include properties such as temperature, pressure, volume, internal energy, enthalpy, entropy, and Gibbs free energy. The value of a state function is determined only by the current state of the system, regardless of the specific processes or intermediates involved in reaching that state. State functions provide a convenient way to describe and analyze the equilibrium and thermodynamic properties of chemical systems, allowing for the prediction and comparison of different states under varying conditions. The features of state function are: 


  • Path Independence: The value of a state function depends solely on the current state of the system and is independent of the path taken to reach that state. It means that the history of how the system arrived at its current state does not matter; only the final state matters.

  • System Property: State functions describe the properties of the system itself rather than the process or pathway by which the system reached that state. They provide information about the current state of the system.

  • Fixed Value at Equilibrium: State functions have well-defined and fixed values at equilibrium. Equilibrium is a state where there is no net change occurring in the system, and the system's state functions reach a stable, unchanging value.

  • Can Be Altered by External Factors: State functions can be changed by altering the conditions of the system, such as temperature, pressure, or composition. However, the change in the state function value depends only on the initial and final states and not on the specific path taken.


Defining Path Function

A path function refers to a property or quantity that depends on the specific path or process taken to reach a particular state of a system. Unlike state functions, which are independent of the path, path functions, such as work and heat, rely on the specific conditions and steps followed during a process. Work is the transfer of energy caused by a force acting through a distance, while heat is the transfer of energy due to a temperature difference. The value of a path function is influenced by the details of the process and is not solely determined by the initial and final states of the system. The features of path function are: 


  • Path Dependence: Unlike state functions, path functions are dependent on the specific path or process taken to reach a particular state of a system. The value of a path function is influenced by the details of the process and is not solely determined by the initial and final states of the system.

  • Transfer of Energy or Work: Path functions often involve the transfer of energy or work. Work is the transfer of energy caused by a force acting through a distance, while heat is the transfer of energy due to a temperature difference.

  • Process Description: Path functions describe the details of the process, including the specific conditions, steps, and intermediates involved in reaching a particular state. They provide information about how the system changes during a process.

  • Not Conserved: Unlike state functions that are conserved and have fixed values at equilibrium, path functions are not conserved and can vary throughout the process.


Differentiate Between State Function and Path Function 

S.No

Category 

State Function 

Path Function

1

Basis

Depends solely on the current state of the system

Depends on the specific path or process taken to reach a particular state

2

Path Independence

Independent of the path taken to reach the state

Dependent on the specific conditions and steps followed during the process

3

System Property

Describes the properties of the system itself

Describes the details of the process or pathway taken to reach the state

4

Equilibrium Value

Well-defined and fixed value at equilibrium

Not conserved and can vary throughout the process

5

Examples

Temperature (T), pressure (P), volume (V), internal energy (U), entropy (S)

Work (W), heat (q)

Symbol Representation

Usually denoted by capital letters (e.g., T, P, V, U, S)

Usually denoted by capital letters (e.g., T, P, V, U, S)


Understanding the distinctions between state functions and path functions is crucial in thermodynamics and the study of chemical systems. State functions describe the current state of a system, while path functions describe the process and energy transfer involved in reaching that state.


Summary 

State functions are properties that depend only on the current state of a system and are independent of how the system reached that state. These functions describe the characteristics or properties of the system at a particular moment and are not affected by the process or path taken to reach that state. Whereas, Path functions, also known as process functions, are properties that depend on the path or process taken to reach a particular state. These functions describe the change or transfer of energy or work that occurs during a process. Some common state functions include temperature (T), pressure (P), volume (V), internal energy (U), enthalpy (H), entropy (S), and Gibbs free energy (G). And some common examples of path functions include work (W) and heat (q).

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FAQs on Difference Between State Function and Path Function for JEE Main 2024

1. What is the significance of state functions in thermodynamics?

State functions are of great significance in thermodynamics as they provide a comprehensive description of a system's equilibrium and thermodynamic properties. These functions, including temperature, pressure, and energy, allow for the calculation and prediction of changes in a system. State functions help establish relationships between various thermodynamic variables and enable the formulation of fundamental laws and principles in thermodynamics. 

2. Why are path functions important in analyzing chemical processes?

Path functions are important in analyzing chemical processes because they provide valuable information about energy transfer, work done, and heat exchange during a process. They describe the specific conditions and steps followed, allowing for a detailed understanding of the process dynamics. Path functions, such as work and heat, enable the calculation and quantification of energy changes, aiding in the determination of system efficiency, heat flow, and mechanical work. By considering the pathway taken, path functions provide a comprehensive picture of the energy transformations occurring in chemical reactions and processes.

3. Can path functions be calculated directly?

Path functions, such as work and heat, cannot be directly calculated solely based on the initial and final states of a system. Unlike state functions, which depend only on the current state, path functions rely on the specific path or process taken. To calculate path functions, additional information about the details of the process is required, such as the forces, displacements, or temperature differences involved. 

4. Is the value of a state function dependent on the process?

No, the value of a state function is not dependent on the process by which the system reached its current state. State functions, such as temperature, pressure, volume, and energy, only depend on the current state of the system and are independent of the pathway taken. Whether the system underwent a direct or indirect route, reversible or irreversible process, the value of a state function remains the same as long as the initial and final states are identical. 

5. Are state functions related to the equilibrium state of a system?

Yes, state functions are directly related to the equilibrium state of a system. They provide information about the current state of the system at equilibrium and can be used to determine equilibrium conditions, as well as calculate changes in energy and other properties. State functions are independent of the pathway taken to reach equilibrium and are solely determined by the current state of the system.