# Why is heat and work a path function?

## Why is heat and work a path function?

Heat and work are forms of energy that are in motion. They exist only when there is a change in the state of system and surroundings. In other words, they are non-existent before and after the change of state. Therefore, the work done is a path function.

How heat and work transfer are path functions explain?

Two important examples of a path function are heat and work. These two functions are dependent on how the thermodynamic system changes from the initial state to final state. These two functions are introduced by the equation ΔU which represents the change in the internal energy of a system.

### How do you prove work done is a path function?

A quantity is said to be state function only when its value depends on the initial and final state, regardless of the path it has followed. But work done is not such quantity. It does depend on the path taken from going state 1 to state 2. So, work done is a path function.

Why heat transfer and work transfer is called a path function?

Heat transfer is a process function (or path function), as opposed to functions of state; therefore, the amount of heat transferred in a thermodynamic process that changes the state of a system depends on how that process occurs, not only the net difference between the initial and final states of the process.

#### Why is work considered a path function?

Work done in a system depends on what path is chosen for performing task to go from state 1 to state 2. So, work is a path function as different routes give different quantities. It does not depend on that path taken as it is measured for a state and not a route. So, it is a state function.

Is work and heat consider as a path function or a point function?

Work (W), heat (Q) are path functions. Point Function: They depend on the state only, and not on how a system reaches that state. All properties are point functions.

## Why is internal energy a state function while both heat and work are path functions?

It does depend on the path taken from going state 1 to state 2. So, work done is a path function. Instead, internal energy is a state function as its value depends on only initial and final temperature i.e., initial and final state of system.

Is heat capacity a path function?

And so heat capacity is a path function not a state function. It’s heat, relative to change in temperature. At constant pressure, on the other hand, we will define a constant pressure heat capacity as, the change in enthalpy with respect to the change in temperature.

### What is difference between heat and work show that heat is a path function and not a property?

Heat transfer is the energy interaction due to temperature difference only while work is not. Heat is low-grade, while work is high-grade. Heat is thermal energy transfer, while work is mechanical energy transfer across the system boundary.

What is meant by point and path function and explain point and path function with a neat sketch?

Path function and Point function are introduced to identify the variables of thermodynamics. Path function: Their magnitudes depend on the path followed during a process as well as the end states. Point Function: They depend on the state only, and not on how a system reaches that state.

#### Why is work not a path function?

State functions depend only on the state of the system, not on the path used to get to that state. Heat and work are not state functions. Work can’t be a state function because it is proportional to the distance an object is moved, which depends on the path used to go from the initial to the final state.

Why is energy a path function yet heat and work are not?

## Why is heat and work called Path functions?

Heat and work are path functions because they depend on the actual path traversed to move from initial to final state of the system. For example, work done is different if a change in state of system is achieved via an isothermal process or an adiabatic process or an isochoric process or an isobaric…

Why is work a path function and point function?

It is because work is a path function. Path function means a quantity that only depends on the path but not on initial and final States. A point function is a quantity that only depends on initial and final States. If you know the end States.

### How do you find the state function of heat?

If you do it by heating the water without doing mechanical work then Δ U = Δ Q so now heat will be a state function as U. But if you do it in a weird way combining heating and doing mechanical work, the work done and the heat transfered in the process would differ from those in the previous examples.

What is the difference between heat and work?

Being path functions, heat and work are defined by the path the system takes from point 1 to point 2. Depending on how we take the system from state 1 to state 2, the heat and work interaction would change, but their difference would be the same, as their difference represents the internal energy .