Short Answer
Thermodynamic equilibrium refers to a state where a system’s temperature, pressure, and chemical composition remain constant over time, with no net exchange of energy or matter. It means the system is balanced internally and with its surroundings, with no driving forces causing changes.
A system in thermodynamic equilibrium satisfies three conditions: thermal equilibrium (uniform temperature), mechanical equilibrium (no pressure changes), and chemical equilibrium (no chemical reactions or composition changes). This concept is essential in thermodynamics for analyzing stable systems, ensuring energy conservation, and studying heat and work interactions.
Detailed Explanation
Understanding Thermodynamic Equilibrium
A system is said to be in thermodynamic equilibrium when all its properties, such as temperature, pressure, and composition, remain constant over time without any external influence. This means there is no unbalanced force or energy transfer occurring within the system.
For a system to be in complete thermodynamic equilibrium, it must satisfy the following conditions:
- Thermal Equilibrium
- There should be no temperature difference between different parts of the system or between the system and surroundings.
- If temperatures are different, heat transfer occurs until equilibrium is reached.
- Mechanical Equilibrium
- There should be no unbalanced forces acting within the system.
- Pressure remains constant throughout the system, preventing movement of fluids or gases.
- Chemical Equilibrium
- The system’s chemical composition does not change over time.
- No new reactions take place, and all substances remain in a stable state.
- Phase Equilibrium (if applicable)
- If multiple phases (solid, liquid, gas) exist, the mass of each phase remains constant.
- There is no evaporation, condensation, melting, or freezing occurring.
Conclusion
Thermodynamic equilibrium is a state where a system maintains constant temperature, pressure, and chemical composition without any energy or mass exchange. It ensures stability by satisfying thermal, mechanical, and chemical equilibrium conditions. Understanding thermodynamic equilibrium is important for analyzing heat transfer, energy conversion, and system stability in mechanical and industrial applications.