Methods for estimating the activity coefficients of strong acids across the concentration range from 1 to 10 mol/l
https://doi.org/10.21285/2227-2925-2019-9-2-232-238
Abstract
The activity coefficient of individual ions is an important parameter in the theory of strong and weak electrolytes in aqueous and non-aqueous solutions. The physical meaning of the average ion coefficient lies in the ratio of the practical and theoretical activity coefficients. If the activity coefficient is set equal to 1 .0, as in the majority of published works, the final calculations can present multiple distorted γ± results. The activity coefficient constitutes a measure of the deviation of real (practical or experimental) parameters from the ideal ones. Ideal parameters are calculated for dilute solutions of non-electrolytes, in which no interactions are assumed to occur. Activity coefficients in high-concentration solutions may reach the values of several tens. However, some empirical data has indicated the dependence of the activity coefficient of electrolytes on their concentration, with some concentrations showing its minimal values. The coefficients equal to several tens, i.e. describing deviations from ideal parameters by the factor of ten, are difficult to adapt for practical application in solutions where association processes or other intermolecular interactions dominate. The present paper describes a number of methods for estimating the average ionic activity coefficients of such strong acids as hydrochloric, hydrobromic, hydroiodic, perchloric, nitric and sulphuric acids across the concentration range from 1 to 10 mol/l. These methods are based on the concepts of nonlinear programming and the method of multi-level modelling of various properties and parameters applied as a calculation tool. According to the performed calculations, the as-estimated activity coefficients of the acids under study are found to be in good agreement with the literature data for the concentration range from 1 to 10 mol/l.
About the Authors
B. B. Tanganov
East Siberian State University of Technology and Management
Russian Federation
Russian Federation
Dr. Sci. (Chemistry), Professor,
Ulan-Ude, Republic of Buryatia
M. E. Zayakhanov
East Siberian State University of Technology and Management
Russian Federation
Russian Federation
Dr. Sci. (Engineering), Professor,
Ulan-Ude, Republic of Buryatia
A. V. Bituyev
East Siberian State University of Technology and Management
Russian Federation
Russian Federation
Dr. Sci. (Engineering), Professor,
Ulan-Ude, Republic of Buryatia
References
1. Kharned G., Ouehn B. Harned H., Owen B. Fizicheskaya khimiya rastvorov elektrolitov [Physical chemistry of electrolyte solutions]. Moscow: Izdatel'stvo inostrannoi literatury Publ., 1952, 628 p.
2. Bates R.G. Determination of pH. Theory and Practice. 2nd ed. New York: John Wiley and Sons, 1973, 398 p.
3. Robinson R.A., Stoks R.G. Rastvory ehlektrolitov [Electrolyte solutions]. Moscow: Izdatel'stvo inostrannoi literatury Publ., 1963, 646 p.
4. Rockwood A.L. Meaning and Measurability of Single-Ion Activities, the Thermodynamic Foundations of pH, and the Gibbs Free Energy for the Transfer of Ions between Dissimilar Materials. Chem. Phys. Chem. 2015, vol. 16, no. 9, pp. 1978–1991. DOI: 10.1002/cphc.201500044
5. Holguín A.R., Delgado D.R., Martínez F., Marcus Y. Solution thermodynamics and preferential solvation of meloxicam in propylene glycol + water mixtures. J. Solution Chem. 2011, vol. 40, pp. 1987–1999.
6. Krishnamoorthy A.N., Zeman J., Holm C., ., Smiatek J. Preferential solvation and ion association properties in aqueous dimethyl sulfoxide solutions. Physical Chemistry Chemical Physics. 2016, vol. 18, no. 45, pp. 31312–31322. DOI: 10.1039/C6CP05909K
7. Roda G., Dallanoce C., Grazioso G., Liberti V., De Amici M. Determination of Acid Dissociation Constants of Compounds Active at Neuronal Nicotinic Acetylcholine Receptors by Means of Electrophoretic and Potentiometric Techniques. Analytical Sciences. 2010, vol. 26, issue 1, pp. 51–54. DOI: https://doi.org/10.2116/analsci.26.51
8. Izmailov N.A. Ehlektrokhimiya rastvorov [Electrochemistry of solutions]. Moscow: Khimiya Pub., 1976, 488 p.
9. Aleksandrov V.V. Kislotnost' nevodnykh rastvorov [Acidity of non-aqueous solutions]. Khar'kov: Vishcha shkola Publ., 1981, 152 p.
10. Krestov G.A. Termodinamika ionnykh protses-sov v rastvorakh. Leningrad: Khimiya Publ., 1984, 272 p.
11. Tanganov B.B., Alexeeva I.A. Model for Calculating the Activity Coefficients of Electrolytes in the 0 to 16 mol/L Range of Concentrations. Russian J. of Physical Chemistry A. 2016, vol. 90, Issue 4, pp. 792–795. DOI: 10.7868/S0044453716040300
12. Tanganov B.B. Modelling of ions mobility in plasmalike concept and transfer processes in electrolyte solutions. Journal of Chemistry and Chemical Engineering. 2013, vol. 7, no. 8, pp. 711–724.
13. Lysova S.S., Skripnikova T.A., Zevatskii Yu.E. Algorithm for calculating the dissociation constants of weak electrolytes and ampholites in water solutions. Russian Journal of Physical Chemistry A. 2017, vol. 91, issue 12, pp. 2366–2369.
14. Tanganov B.B., Alekseeva I.A. A Method for Calculationg the Acid-Base Equilibria in Aqueous and Nonaqueous Electrolite Solutions. Russian Journal of Physical Chemistry A. 2017, vol. 91, issue 6, pp. 1149–1151. DOI: 10.1134/S0036024417060243
15. Tanganov B.B. The method of multi-level modeling in the evaluation of physico-hemical parameters of solvents. IV. Isothermal changes of thermodynamic functions from an ideal state. Mezhdunarodnyi zhurnal eksperimental'nogo obrazovaniya. 2015, no. 11–3, pp. 433–436. (In Russian)
Review
For citations:
Tanganov B.B., Zayakhanov M.E., Bituyev A.V. Methods for estimating the activity coefficients of strong acids across the concentration range from 1 to 10 mol/l. Proceedings of Universities. Applied Chemistry and Biotechnology. 2019;9(2):232-238. (In Russ.) https://doi.org/10.21285/2227-2925-2019-9-2-232-238
Views:
332
Email this article 