Reversible Processes vs. Irreversible processes

[105743571]

I am still kind of confused about the differences between the processes so can someone make sure my reasoning is correct?

A reversible process is the idea that gas will compress if Papplied>Pgas and will expand if Pgas> Papplied to maintain mechanical equilibrium. In other words, if you compress a gas, the gas will apply pressure back to the main equilibrium. In a sense, a system will return to this original state without the addition of work. Conversely, irreversible processes will not return to equilibrium. For example, if a gas is compressed, the gas will not push back as there is no tendency to return back to equilibrium. In a sense, the pressure of your system is constant as it does not change.

Is this correct?

[Aditya Desai 1A]

I could be wrong too, but not quite. The mathematical relation you made holds for both processes. All systems tend to equilibrium where achievable. "Reversible" in a thermodynamics context refers to the reversibility of a reaction with an *infinitesimal* change only. So if I need to increase/decrease the external pressure by a measurable amount to bring about a change, the process is by this definition irreversible.

From the textbook: "This common usage is refined in science: in thermodynamics, a reversible process is one that can be reversed by an infinitely small change in a variable (an “infinitesimal” change)."

[Meghan Spoeri 2D]

From what I found, conceptually, a reversible process is a process in which the system and environment can be restored to exactly the same initial states that they were in before the process occurred, whereas an irreversible process is where the system and its environment cannot be restored to their original states at the same time. Irreversible processes occur much more in real life.

[Arjun_Anumula_3E]

Yes, you explained it pretty well. Irreversible processes do not return to equilibrium (e.g. turn from expansion back to compression) with only a small change of say the external environment. This would be the case in say an isothermal reversible expansion, where the outside pressure matches the inside pressure throughout the expansion.