REVERSIBLE AND IRREVERSIBLE PROCESS
A reversible process is defined as a process that can be reversed without leaving any
trace on the surroundings. It means both system and surroundings are returned to their initial
states at the end of the reverse process.
Reversible processes do not occur and they are only idealizations of actual processes.
We use reversible process concept because, a) they are easy to analyze (since system passes
through a series of equilibrium states); b) they serve as limits (idealized models) to which the
actual processes can be compared.
Some factors that cause a process to become irreversible:
• Friction
• Unrestrained expansion and compression
• Mixing
• Heat transfer (finite ΔT)
• Inelastic deformation
• Chemical reactions
In a reversible process things happen very slowly, without any resisting force, without
any space limitation → everything happens in a highly organized way (it is not physically
possible ‐ it is an idealization).
Internally reversible process: if no irreversibilities occur within the boundaries of the
system. In these processes a system undergoes through a series of equilibrium states, and
