Which condition best describes thermodynamic equilibrium in a closed physical system?
Show answer & explanation
Correct answer: B
Explanation
Solution: The correct answer is When temperature, pressure, and chemical potential remain uniform and constant throughout the system over time.
Explanation:
☛ A system is said to be in thermodynamic equilibrium when its macroscopic state variables do not change with time and no net flows of matter or energy occur within the system or between the system and its surroundings.
☛ For thermodynamic equilibrium to exist, three specific conditions must be fulfilled simultaneously:
1. Thermal Equilibrium: The temperature is uniform throughout the system, meaning there is no net heat transfer.
2. Mechanical Equilibrium: The pressure remains balanced and uniform, meaning there are no unbalanced forces causing movement.
3. Chemical Equilibrium: The chemical potential remains uniform, meaning no net chemical reactions or mass transfers occur.
Extra Exam-Relevant Facts:
☛ Zeroth Law of Thermodynamics: States that if two systems are each in thermal equilibrium with a third system, they are also in thermal equilibrium with each other, establishing the basis for the measurement of temperature.
☛ Entropy at Equilibrium: In an isolated system, entropy reaches its maximum possible value when the system reaches thermodynamic equilibrium.
☛ Third Law of Thermodynamics: States that the entropy of a pure, perfectly crystalline substance becomes zero at absolute zero temperature (0 K or -273.15 °C).
☛ State Variables: Properties like pressure, temperature, volume, and internal energy depend solely on the current state of the system, not on the path taken to reach that state.
Important One-Liners for Upcoming Exams:
☛ Which law of thermodynamics introduces the concept of temperature? → Zeroth Law of Thermodynamics
☛ What happens to the entropy of an isolated system at thermodynamic equilibrium? → It reaches its maximum value
☛ What is the value of absolute zero temperature on the Celsius scale? → -273.15 °C
☛ Which parameter remains constant during an isothermal process? → Temperature
☛ What is a thermodynamic process called in which no heat enters or leaves the system? → Adiabatic process