The Determination of Heat Capacity Hoteos in o Simp9e Open System

摘要

Typically, introductory courses in physical chemistry avoid the treatment of open thermodynamics systems by introducing imaginary boundaries to artificially ensure closure. When an experiment is performed to measure some physical quantity, which by its nature is physically open, the scheme of simulating an open system as a closed one can uncouple the accompanying theoretical discussion from the practicality of the experiment. The Clement and Desormes experiment (1) is an enticing example of an experiment in which an open system is invariably treated as closed. Their experiment will provide the conceptual framework for this article: to test the value of an open system approach against other known results. The basic procedure involves removing the cap of a rigid vessel with diathermal walls, containing a gas at a pressure slightly above the ambient pressure, and then quickly replacing the cap. When the cap is removed, gas flows out of the vessel as it expands adkbatically to atmospheric pressure. Replacing the cap allows the cooler gas co warm isochorically to its original temperature.