In case of the following questions, a statement I is given followed by a corresponding statement II just below it. Mark the correct answer.
Statement I: In irreversible processes changes are carried out through quasi-equilibrium state.
Statement II: In reversible process changes are carried out so slowly that the system and surroundings are always in near equilibrium.
Answer & explanation
Correct answer: option 4
The correct answer is option 4. Statement I is false and statement II is true.
To understand the detailed explanation, let's break down each statement and the concepts involved.
Statement I: In irreversible processes changes are carried out through quasi-equilibrium state.
Irreversible Processes: Irreversible processes are those that cannot be reversed by infinitesimal changes in a variable. They occur spontaneously and involve non-equilibrium states.
Characteristics:
Finite Gradients: They typically involve finite differences in temperature, pressure, or concentration between the system and its surroundings, leading to rapid changes.
Dissipation of Energy: These processes often result in the dissipation of energy as heat or work (e.g., friction, turbulence).
Non-equilibrium States: The system is not in equilibrium at all stages of the process.
Quasi-equilibrium State: A quasi-equilibrium (or quasi-static) state is one where the process occurs infinitesimally slowly, allowing the system to pass through a continuous series of equilibrium states.
Characteristics:
Near-Equilibrium: The system is always infinitesimally close to equilibrium.
Infinitesimal Changes: Changes occur so slowly that the system has enough time to adjust to the surroundings, maintaining near-equilibrium conditions.
Since irreversible processes do not maintain equilibrium or near-equilibrium states, Statement I is false.
Statement II: In reversible processes changes are carried out so slowly that the system and surroundings are always in near equilibrium.
Reversible Processes: Reversible processes are idealized processes that can be reversed without leaving any change in both the system and the surroundings.
Characteristics:
Infinitesimal Changes: Changes occur extremely slowly, allowing the system and surroundings to adjust continuously.
Continuous Equilibrium: The system passes through an infinite number of equilibrium states, ensuring that the process is quasi-static.
No Dissipation: There is no loss of energy due to irreversibilities like friction or turbulence.
Since reversible processes involve infinitesimally slow changes that keep the system and surroundings in near-equilibrium, Statement II is true.
Summary:
Irreversible Processes: Rapid changes, non-equilibrium states, energy dissipation.
Reversible Processes: Infinitesimally slow changes, continuous equilibrium states, no energy dissipation
Conclusion:
Based on the definitions and characteristics: Statement I is false because irreversible processes do not maintain quasi-equilibrium states. Statement II is true because reversible processes are characterized by infinitesimally slow changes that maintain near-equilibrium.