A thermally isolated sample of an ideal gas at a fixed temperature is confined to one half of a container by an impermeable membrane. The other half of the container is evacuated. The membrane is then pierced and the gas is allowed to expand freely and to double its volume as shown. Which one of the following statements is true concerning this situation?

Question

Quizplus · Accepted Answer

Since the gas is at a fixed temperature, the process must be isothermal. The expansion is not reversible because the gas is expanding into a vacuum. The entropy of the gas increases with the expansion, so C is incorrect. The internal energy of the gas does not necessarily decrease, so D is incorrect. The temperature of the gas remains constant during an isothermal process, so E is incorrect.

A Thermally Isolated Sample of an Ideal Gas at a Fixed