Structural Fragments Izopolivolframat–Anions and Gibbs Energy of Formation

• Main Author: G. M. Rozantsev
• Format: Article
• Language: English
• Published: Vasyl Stefanyk Precarpathian National University 2016-10-01
• Series: Фізика і хімія твердого тіла
• Online Access: http://journals.pu.if.ua/index.php/pcss/article/view/810

The method of mathematical modeling (program CLINP 2.1, Newton's method) on the basis of the pHpotentiometrictitration data allowed to calculate concentration constants of isopolytungstate anions (IPTA)formation at different ionic forces (I = 0,01 - 0,5 M). Thermodynamic constants of IPTA formation were obtainedas a result of processing by Pitzer method using the concentration constans. The standard Gibbs energy ofisopolytungstate anions formation were calculated. The last ones allowed to estimate the thermodynamicprobability of the reactions, that can be used in the synthesis of salts containing these anions. The structure ofknown isopolytungstates can be built from the combination of such fragments: WO, W2O, W3O, W4O and W5O.The calculation of standard Gibbs energy of these fragments formation allowed to characterize the structure ofhexatungstate-anion W6O20(OH)26-, which does not contain three terminal oxygen atoms. Such approach of usingGibbs energy of building blocks was recommended for prediction of equilibrium constants values in themathematical modeling. <br /><strong>Keywords:</strong> isopolytungstate anions, standard Gibbs energy of formation.