04-11-2018, 02:08 PM

I struck with a question , I know work and heat are path function overall . But what if We apply some constrain , their behavior will also change .

I reached to the conclusion , Yes they can be state function in following conditions .

Work

at constant pressure

ΔU = q + w

ΔU = ΔH + w

w = ΔU - ΔH

since we can express it in the form of sum of two state function it is a state function .

I visualized graphically it on PV diagram , if reversible process then there will be only one pathway to go from one state to another that is constant pressure path (horizontal line) .

Q.1 Can we visualize for irreversible change graphically ??

Adiabatic condition

ΔU = w

So w must be state function.

but what about at constant volume .

w = 0 , no matter which path you will take, you always end with zero work .

Q.2 so can we say null function is also a state function ??

I also thought that it's differential will also be exact because you will get everytime 0 .

same question is with heat in a adiabatic process ??

I reached to the conclusion , Yes they can be state function in following conditions .

Work

at constant pressure

ΔU = q + w

ΔU = ΔH + w

w = ΔU - ΔH

since we can express it in the form of sum of two state function it is a state function .

I visualized graphically it on PV diagram , if reversible process then there will be only one pathway to go from one state to another that is constant pressure path (horizontal line) .

Q.1 Can we visualize for irreversible change graphically ??

Adiabatic condition

ΔU = w

So w must be state function.

but what about at constant volume .

w = 0 , no matter which path you will take, you always end with zero work .

Q.2 so can we say null function is also a state function ??

I also thought that it's differential will also be exact because you will get everytime 0 .

same question is with heat in a adiabatic process ??