Reversible and Irreversible Processes
Reversible process: A process that can be reversed without leaving any trace on the surroundings.Irreversible process: A process that is not reversible.
The factors that cause a process to be irreversible are called IRREVERSIBILITIES.
They include:
- Friction
- Unrestrained expansion
- Mixing of two fluids
- Heat transfer across a finite temperature difference
- Electric resistance
- Inelastic deformation of solids
- Chemical reactions
Internally and Externally Reversible Processes
Internally reversible process: If no irreversibilities occur within the boundaries of the system during the process.
Externally reversible: If no irreversibilities occur outside the system boundaries.
Totally reversible process: It involves no irreversibilities within the system or its surroundings i.e. no heat transfer through a finite temperature difference, no nonquasi-equilibrium changes, and no friction or other dissipative effects.
Friction renders a process irreversible