Condensed Matter Physics, 2011, vol. 14, No. 3, 33003: 115
DOI:10.5488/CMP.14.33003
arXiv:1202.4259
Title:
Primitive model electrolytes. A comparison of the HNC approximation for
the activity coefficient with Monte Carlo data
Author(s):

E. GutiérrezValladares
(Centro de Física Aplicada y Tecnología
Avanzada, Universidad Nacional Autónoma de México, A.P.
11010, 76000 Querétaro, México,
University of Ljubljana, Faculty of Chemistry and
Chemical Technology, Aškerčeva c. 5, SI1000 Ljubljana,
Slovenia
),


M. Lukšič
(University of Ljubljana, Faculty of Chemistry and
Chemical Technology, Aškerčeva c. 5, SI1000 Ljubljana,
Slovenia),


B. MillánMalo
(Centro de Física Aplicada y Tecnología
Avanzada, Universidad Nacional Autónoma de México, A.P.
11010, 76000 Querétaro, México),


B. HribarLee
(University of Ljubljana, Faculty of Chemistry and
Chemical Technology, Aškerčeva c. 5, SI1000 Ljubljana,
Slovenia),


V. Vlachy
(University of Ljubljana, Faculty of Chemistry and
Chemical Technology, Aškerčeva c. 5, SI1000 Ljubljana,
Slovenia)

Accuracy of the mean activity coefficient expression
(HansenVieillefosseBelloni equation), valid within the
hypernetted chain (HNC) approximation, was tested in a wide
concentration range against new Monte Carlo (MC) data for +1:1
and +2:2 primitive model electrolytes. The expression has an
advantage that the excess chemical potential can be obtained
directly, without invoking the time consuming GibbsDuhem
calculation. We found the HNC results for the mean activity
coefficient to be in good agreement with the machine calculations
performed for the same model. In addition, the thermodynamic
consistency of the HNC approximation was tested. The mean activity
coefficients, calculated via the GibbsDuhem equation, seem to
follow the MC data slightly better than the
HansenVieillefosseBelloni expression. For completeness of the
calculation, the HNC excess internal energies and osmotic
coefficients are also presented. These results are compared with
the calculations based on other theories commonly used to describe
electrolyte solutions, such as the mean spherical approximation,
Pitzer's extension of the DebyeHückel theory, and the
DebyeHückel limiting law.
Key words:
primitive model electrolyte, mean activity coefficient,
hypernettedchain approximation, mean spherical approximation,
Monte Carlo simulation, Pitzer's approach, DebyeHückel theory
PACS:
02.30.Rz, 05.10.Ln, 05.20.Jj, 05.70.Ce, 82.45.Gj, 82.60.Lf
