Compilation and estimation of the thermodynamic properties of solid ortho-, meta- and pyrophosphates
I - standard molar entropies and standard molar heat capacities
for solid phosphates
A. Ait-Hou1*, T. Rais2, C. Chatillon3
1Laboratoire des Ressources Naturelles et d’Environnement, Département de Chimie , Faculté des Sciences et Techniques, B.P.509, Boutalamine, Errachidia, Morocco
2Département de Chimie, Faculté des Sciences casa1, Morocco
3Laboratoire de Thermodynamique et Physico-chimie Métallurgiques, (CNRS, UMR 5614 UJF/INPG ), E.N.S.E.E.G., Domaine Universitaire, B.P.75, 38402 Saint-Martin d'Hères, France
* Corresponding author. E-mail:email@example.com
Received: 11 October 2003; revised version accepted: 25 August 2005
Thermodynamic of condensed phosphates are reviewed in order to check usual models to estimate their properties. For standard molar entropies S and standard molar heat capacities C(298.15 K), the rule of additivity of oxides entropies seems the best way with an accurancy of 2% and we have used this rule to generate thermodynamic data of alkaline, alkaline-earth, transition, rare-earth and "p" metals phosphates. C(T) are calculated using the formula proposed by Kellog, but this reliability cannot be ascertained since informations about allotropic transitions are scarce.
Keywords: Thermodynamics of phosphates; Entropies; Heat capacities.