If a gas expands freely into a vacuum,
A)the expansion is adiabatic, so the gas does work on its environment and its internal energy decreases.
B)the expansion is isothermal.
C)the expansion is occurs at constant pressure.
D)the expansion is adiabatic but no work is done, so the internal energy of the gas and its temperature both decrease.
E)the expansion is adiabatic but no work is done, so the internal energy of the gas and its temperature do not change.

Question

Quizplus · Accepted Answer

In a free expansion into a vacuum, the gas does not do work on its surroundings because there is no external pressure to work against. Since no heat is exchanged (adiabatic) and no work is done, the internal energy of the gas remains constant, leading to no change in temperature according to the first law of thermodynamics.

If a Gas Expands Freely into a Vacuum