Question:medium
In case of free expansion, which one of the following statements is WRONG ______.
In case of free expansion, which one of the following statements is WRONG ______.
Show Hint
To draw any line on a P-V graph, you must know the exact pressure at every millisecond. In explosions or free expansions, the gas is in chaotic turmoil, making a single defined "Pressure" impossible to measure!
Updated On: Jun 19, 2026
- It is an instantaneous change.
- The system is not in thermodynamic equilibrium.
- Free expansion can be plotted on a P-V diagram.
- It is an uncontrolled change.
Show Solution
The Correct Option is C
Solution and Explanation
Step 1: Understanding the Concept:
Free expansion is an irreversible process where a gas expands into a vacuum. It happens so fast and turbulently that intermediate states are not defined.
Step 2: Formula Application:
Work $W = 0$ (since $P_{ext} = 0$).
Step 3: Explanation:
Because the process is highly non-equilibrium, the pressure and volume are not uniform throughout the system during the expansion. Only the initial and final equilibrium states are known, so the path cannot be plotted as a continuous line on a P-V diagram.
Step 4: Final Answer:
Statement (c) is wrong.
Free expansion is an irreversible process where a gas expands into a vacuum. It happens so fast and turbulently that intermediate states are not defined.
Step 2: Formula Application:
Work $W = 0$ (since $P_{ext} = 0$).
Step 3: Explanation:
Because the process is highly non-equilibrium, the pressure and volume are not uniform throughout the system during the expansion. Only the initial and final equilibrium states are known, so the path cannot be plotted as a continuous line on a P-V diagram.
Step 4: Final Answer:
Statement (c) is wrong.
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