Reversible Process

[madison_bang_1L]

Hello!

I wanted to ask for clarification as to what a reversible process entails. The textbook defines it as a process that can be reversed by an infinitely small change in a variable. Would anyone be able to give an example? The textbook also establishes that to make a process reversible, the external pressure must be reduced with the change in volume so P(ex) = P(gas). Is that so the "infinitely small change" in pressure can take place? Any explanation would be much appreciated.

Thank you!

[Austin_Schwartz_1L]

Hello,
An example of a reversible process that the book provides is the isothermal expansion of ideal gas. The gas is in contact with a constant temperature water bath, which maintains the constant temperature of the gas. External pressure must be reduced as the gas expands because if it was not then the external pressure would not be the same as the pressure of the gas. More about this topic can be found in section 4A.3 of the textbook.
I hope this helps!

[Jeffrey Yang 3I]

One different way to look at reversible processes is the change in the system and change in the environment. For irreversible processes, there is a net change in the system, which leads to a net change in the environment, because the sum of these two changes must be 0. If something is lost or gained by the environment, it is irreversible because this cannot be "returned" back to the system.

For reversible processes, there is no net change in the system and no net change in the environment, therefore. This means that some change occurred within the system, but there is no net change. If this is the case, the process is reversible because nothing is lost or gained by the environment.

[Nandini_Parmar_1I]

Reversible processes often include small scale changes within the system. These changes can be moved back to their original states because nothing is lost/gained by the environment.

Irreversible processes are processes that are on a larger scale and cannot be reversed. Ex: lighting a paper on fire.