Determinación de presiones parciales: el caso de H$_2$O(v) en aire

Abstract

In introductory Classical Thermodynamics courses, the Equations of State topic is necessarily revised, and the one or more components PVT systems, are the selected examples in almost all the cases. For multicomponent systems, the understanding of the concept of component partial pressure is required. Although the revision in classroom is feasible, the experimental study is difficult; for example, selective pressure sensors are required for the specific measurement of manometric pressures, which are far from being common in teaching undergraduate laboratories. This difficulty can be avoided if certain gaseous fluid mixtures are chosen, as atmospheric air, and the study is focused on the behavior of H$_2$O(v) contained in the air. In fact, this is what is called Psychrometry. In this communication, the psychrometric basis, the experimental development and the results concerning the H$_2$O(v) partial pressure in a local atmospheric air determination, are presented. As a complement, the air temperature value (dew point) at which the H$_2$O(v) becomes a saturated vapor (isobaric process), is obtained.