Question

Which of the following statements is FALSE?

• A. Entropy is a state function
• B. Heat is a state function
• C. Internal energy is a state function
• D. Gibbs free energy is a state function

Hint:

Easy way to remember:
State Functions: $P, V, T, U, H, S, G$ (have exact differentials).
Path Functions: Heat ($Q$) and Work ($W$) (have inexact differentials).

Answer 1

The Correct Option is B

Step 1: Understanding the Question:
The question asks to identify the false statement among the options regarding state functions in thermodynamics.

Step 2: Key Formula or Approach:
- State Function: A property whose value depends only on the current state of the system, not on how the system reached that state (e.g., $U, S, G, H, P, T, V$).
- Path Function: A quantity whose value depends on the specific path followed during a transition (e.g., Heat $Q$ and Work $W$).

Step 3: Detailed Explanation:

• Statement A is True: Entropy ($S$) is a thermodynamic state function. The change in entropy ($\Delta S$) between two states is independent of the path.

• Statement B is False: Heat ($Q$) is not a state function; it is a path function. The amount of heat exchanged during a process depends on the specific path taken (e.g., constant volume vs. constant pressure).

• Statement C is True: Internal energy ($U$) is a state function. Although $Q$ and $W$ are path functions, their difference ($dU = dQ - dW$) is independent of the path and represents a change in a state function.

• Statement D is True: Gibbs free energy ($G = H - TS$) is defined entirely using state functions, making it a state function itself.

Step 4: Final Answer: The false statement is: "Heat is a state function."