Question

Describe how reversible and irreversible expansions differ by discussing the degree to which equilibrium is maintained between the system and the surroundings.

Answer 1

Reversible process is a process whose direction can be "reversed" by inducing infinitesimal changes to some property of the system via its surroundings, As a result the system and surroundings are always in equilibrium.

Irreversible process is a process whose direction can't be "reversed" by inducing infinitesimal changes to some property of the system via its surroundings, As a result the system and surroundings are not always in equilibrium

For example , when there is expansion, work is done. If same work is applied in reversbile process, the system can be brought to initial state.   This is not the case in case of irreversible expansion.