Chemical Thermodynamics 3.4 - Reversible Processes

Short physical chemistry lecture on the reversible expansion and compression of ideal gases.
When the external pressure of a system's surroundings is equal to the pressure of the gas for every step of a process, the process is said to be reversible. The reversible work is equal to the minimum compression work and maximum expansion work of a process.
Notes Slide: i.imgur.com/cHhhSnd.png
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[@jnevski123]

You're a saint

[@TMPChem]

Excellent. I'll inform the Pope.

[@michelm.6704]

Nice video ! But I don't really understand one thing when you are saying that if Pext=Pgaz and we want to perform a compression to our system , we perform the MINIMUM compression work . It suggest that it is possible to do a strictly higher magnitude compression work than the magnitude of the reversible work , but since work=( distance)*( OPPOSITE force) , when we compress our gas , the opposite force can ONLY correspond to Pgas since Pgas represents to the force we are facing with . So i would replace the ">=" by " = " between compression work and reversible work in the inequality. Am i wrong ?

[@theblackherald]

What is the difference then, between an isothermal process and an a general reversible process? The work equations seem the same

[@chocolatecake9355]

For a reversible process, the exact amount of energy transferred to the surroundings by the expansion of the gas can be transferred back to the gas since all the energy exchanged between the system and surroundings was in the form of work?

[@TMPChem]

Not exactly. The reason the process is "reversible" is because when we perform an expansion and the corresponding compression to reverse it (or vice versa) there is no net work done during the process which starts and ends in the same state. This is equivalent to saying that no entropy is created during the process, which is required by the second law of thermodynamics in order for a process to be reversible. Much more on reversibility is discussed in the next chapter. It doesn't matter whether or not heat is involved in the process. Isothermal expansions include heat. Adiabatic expansions don't. Both can be done reversibly or irreversibly.

[@chocolatecake9355]

TMP Chem Thank you so much! This makes so much more sense!

[@BoxOfCurryos]

dude thanks

[@user-in4sg1nt4t]

The heading should be Isothermal reversible as you assumed temperature to be constant

[@TMPChem]

This chapter includes discussions of both isothermal reversible and adiabatic reversible processes in the proceeding videos.

[@SoumilSahu]

is this what is called a quasi static process??

[@TMPChem]

Yes. All reversible processes are quasi static processes, i.e. they happen infinitely slowly. No real processes can be done 100% reversibly, but we can approximate them well by changing the system very very slowly from one state to another.

[@SoumilSahu]

thanks for the quick reply!

[@somelifeguard]

The pop-ups every two seconds for "next video, previous video, course introduction, etc" are really annoying and makes me hate these videos.