Consider a system consisting of the following apparatus, in which gas is confined in one flask and there is a vacuum in the other flask. The flasks are separated by a valve. Assume that the flasks are perfectly insulated and will not allow the flow of heat into or out of the flasks to the surroundings. When the valve is opened, gas flows from the filled flask to the evacuated one. (a) Is work performed during the expansion of the gas? (b) Why or why not?

Key Concepts

Work in Thermodynamics

In thermodynamics, work is defined as the energy transferred when a force is applied over a distance. For gases, work can occur during expansion or compression when the gas exerts pressure on its surroundings. In the context of the question, understanding whether work is done during the gas expansion involves analyzing the system's boundaries and the nature of the expansion process.

Free Expansion

Free expansion refers to the process where a gas expands into a vacuum without performing work on the surroundings. In this scenario, since the gas moves from a filled flask to an evacuated one, there is no opposing pressure to work against, meaning no energy is transferred as work. This concept is crucial for determining whether work is done during the gas's expansion.

First Law of Thermodynamics

The First Law of Thermodynamics states that energy cannot be created or destroyed, only transformed from one form to another. In an insulated system, the internal energy change is equal to the heat added to the system minus the work done by the system. Since there is no heat exchange and no work done during the free expansion, the internal energy of the gas remains constant, which is essential for understanding the energy dynamics in this scenario.