Abstract
The molality-based osmotic coefficients of aqueous mixtures of KBr and K2HPO4 have been measured at T=(298.15±0.01)K by the isopiestic method at KBr ionic strength fractions y=(0.18328, 0.38241, 0.58031, 0.79186, and 1) and over the ionic strength range (2.5452 to 10.0418)mol·kg−1, using KCl(aq) and CaCl2(aq) as the reference standard solutions. These experiments were performed using glass sample dishes because preliminary experiments showed that some corrosion of our usual gold-plated silver dishes occurred with dissolution of silver, presumably by “pinhole” corrosion at imperfections in the gold layer. These osmotic coefficients were modeled with an extended form of Pitzer’s ion-interaction model equations, both with the usual Pitzer mixing terms and with Scatchard’s neutral-electrolyte mixing terms, and with the Clegg–Pitzer–Brimblecombe equations based on the mole-fraction-composition scale. There are no previously published isopiestic measurements for this ternary system. The present assessment yields mixing parameters for these models. Model parameters for KBr(aq) at T=(298.15±0.01)K were also evaluated using the present results along with four sets of osmotic coefficients taken from the published literature. For the {yKBr+(1−y)K2HPO4}(aq) system, the model with five Scatchard mixing terms gave a significantly better representation of the osmotic coefficients than any of the other models and is therefore recommended for calculation of osmotic and activity coefficients.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.