Question:easy
During the free expansion of an ideal gas, which of the following physical quantity remains constant
During the free expansion of an ideal gas, which of the following physical quantity remains constant
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Remember: Free expansion is neither reversible nor quasi-static. While $T_i = T_f$, the intermediate states are undefined, and the entropy of the system increases significantly.
Updated On: Jul 1, 2026
- Temperature
- Pressure
- Volume
- Ratio of pressure to volume
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The Correct Option is A
Solution and Explanation
1. Work Done ($W$): Since the gas expands against a vacuum (zero external pressure), no work is done by the gas: $W = 0$.
2. Heat Exchange ($Q$): Free expansion is typically an adiabatic process in a perfectly insulated system, meaning no heat enters or leaves: $Q = 0$.
3. Internal Energy ($U$): According to the First Law, $\Delta U = Q - W$. Since both $Q$ and $W$ are zero, $\Delta U = 0$. The internal energy remains constant.
2. Heat Exchange ($Q$): Free expansion is typically an adiabatic process in a perfectly insulated system, meaning no heat enters or leaves: $Q = 0$.
3. Internal Energy ($U$): According to the First Law, $\Delta U = Q - W$. Since both $Q$ and $W$ are zero, $\Delta U = 0$. The internal energy remains constant.
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