Question

Which of the following is not a property of a thermodynamic system?

• A. Internal energy
• B. Heat
• C. Pressure
• D. Temperature

Hint:

State functions (Properties) = Pressure, Volume, Temperature, Internal Energy, Enthalpy, Entropy. Path functions (Not properties) = Heat and Work.

Answer 1

The Correct Option is B

Step 1: Understanding the Question:
We must distinguish between thermodynamic properties (state functions) and path functions. A thermodynamic property describes the state of a system regardless of how it arrived at that state.
Step 2: Detailed Explanation:
Let's analyze the options:
(A) Internal Energy ($U$): This is a state function. It depends only on the current state of the system (like Temperature and Volume) and is a definitive property.
(C) Pressure ($P$): This is a macroscopic state variable and clearly a property of the system.
(D) Temperature ($T$): This is also a fundamental state variable representing thermal equilibrium and is a property of the system.
(B) Heat ($q$): Heat is defined as energy in transit due to a temperature difference. It is a path function, meaning the amount of heat transferred depends heavily on the specific process (path) taken to go from an initial to a final state. A system does not "contain" heat; it contains internal energy. Therefore, heat is not a property of the system itself.
Step 3: Final Answer:
Heat is not a property of a thermodynamic system.