par Hayez, Bernard 
Référence Journal of chemical education, 95, 11, page (1982-1988)
Publication Publié, 2018-11-01
Référence Journal of chemical education, 95, 11, page (1982-1988)
Publication Publié, 2018-11-01
Article révisé par les pairs
| Résumé : | From a physical point of view, the partial pressure of a component i in a gas mixture is defined as the contribution of molecules i to the force per unit area that the molecules of the mixture exert on the wall. The relation pi = xiP (where xi is the mole fraction of i and P the total pressure) is in agreement with this definition for perfect gases, but not for real gases. For lack of a general macroscopic equation for the partial pressure in real gas mixtures, the product xiP is used as operational partial pressure. Using the virial expansion applied to the equation of state of nonideal gas mixtures truncated to the second order, we obtain an approximate equation of the partial pressures for such mixtures. This equation allows for a comparison with xiP as well as for the creation of diagrams expressing the total and partial pressures of the various constituents as a function of composition. Such diagrams prove useful to tackle this delicate subject with students, from a conceptual and from an educational point of view. |
