Question

(a) What is meant by calling a process irreversible? (b) After an irreversible process the system is restored to its original state. What can be said about the condition of the surroundings after the system is restored to its original state? (c) Under what conditions will the condensation of a liquid be an irreversible process?

Short answer

(a) An irreversible process is one in which the system and its surroundings cannot be returned to their original states due to energy loss in forms such as heat, friction, or work. (b) When a system is restored to its original state after an irreversible process, the surroundings will not be in their initial state due to unrecoverable energy transfers during the process. (c) The condensation of a liquid becomes an irreversible process when it occurs at a temperature below its boiling point, when external work is done on the system, or when there is an external heat transfer.

Step-by-step solution

(a) Definition of Irreversible Process

An irreversible process is a process in which the system and its surroundings cannot be returned to their original states after the process has occurred. This is mainly because an irreversible process usually involves some loss in the form of heat, friction, or other forms of energy, making it impossible to reverse the process and get back to the initial state.

(b) Condition of the surroundings after the system is restored to its original state

When a system undergoes an irreversible process and is then restored to its original state, the surroundings will not be in their initial state. This is because during the irreversible process, energy has been transferred between the system and the surroundings in a way that cannot be reversed. The surroundings might have gained or lost heat, work, or other forms of energy, which cannot be completely recovered.

(c) Conditions for the condensation of a liquid to be an irreversible process

The condensation of a liquid becomes an irreversible process under the following conditions: 1. When the liquid condenses at a temperature below its boiling point: This is because the liquid has released heat during condensation, which cannot be recovered if the process is reversed, leading to irreversibility. 2. When external work is done on the system during the condensation process: In this case, if the process is reversed, the external work done will not be recoverable, leading to the irreversibility of the condensation process. 3. When the condensation occurs with an external heat transfer: This means that the heat transfer between the system and its surroundings cannot be reversed during the condensation process, making it irreversible.