Volumetric properties and the ion-interaction parameters of the binary system (CsB5O8 + H2O) at temperatures from (283.15 to 363.15) K and 101 kPa

This paper reports the densities of CsB 5 O 8 (aq) in the range of salt concentrations from 0.02526 to 0.08148 mol·kg −1 , which were determined by an accurate Anton Paar Digital vibrating-tube densimeter at 5 K intervals from 283.15 to 363.15 K and 101 kPa. The apparent molar volume ( V ϕ ), the coefficient of thermal expansion ( α ), apparent molar expansibility of the solute ( ϕ E ) were calculated and variations of these properties against temperature and concentration were revealed minutely. According to Pitzer ion-interaction apparent molar volume model of aqueous electrolyte system, the Pitzer single salt parameters i.e. F MX ( β M X 0 v , β M X 1 v and C M X v , M = Cs + , X  = [B 5 O 6 (OH) 4 ] - ), the temperature-dependence equation [ F MX ( i , p , T ) =  a 1  +  a 2 ln(T/298.15) +  a 3 (T-298.15) +  a 4 /(620-T) +  a 5 (T-227), i = β M X 0 v , β M X 1 v and C M X v ] as well as their coefficients a i ( i  = 1 to 5) in the binary system were obtained, which is not reported in the literature. The fitted results of single salt parameters β M X 0 v , β M X 1 v and C M X v were in good agreement with the experiment values, indicating that the single salt parameters and temperature relational coefficients for Cs[B 5 O 6 (OH) 4 ] obtained in this work are reliable.