Activity coefficient assumptions in the determination of association constants. V. Association of thallium(I) bromide from solubility measurements

1969 ◽  
Vol 22 (5) ◽  
pp. 911 ◽  
Author(s):  
CW Childs ◽  
MH Panckhurst

Measurements are reported of the solubility of thallium(I) bromide in aqueous solutions of potassium bromide, sodium perchlorate, barium bromide, and of mixtures of sodium bromide and sodium perchlorate and of sodium bromide and sodium acetate at 25�. The measurements are used to test the merits of two types of ionic activity coefficient expressions, one assuming specific interactions between free ions and the other not. It is shown that neither expression can describe our results adequately, in contrast to previous solubility results with thallium(I) chloride for which the specific interaction expression was adequate.


1967 ◽  
Vol 20 (12) ◽  
pp. 2633 ◽  
Author(s):  
KH Khoo ◽  
MH Panckhurst

Measurements are reported of the solubility of thallium(I) chloride in aqueous solutions of sodium acetate and thallium(I) perchlorate and in solutions of sodium chloride, barium chloride, and sodium perchlorate in 16.7, 30, and 60 wt. % methanol-water mixtures. The measurements in water are used to test the merits of two types of ionic activity coefficient expression. It is shown that it is necessary to take account of specific interactions between free ions and that this also allows for small amounts of other association reactions in the same solution. The possibility of allowing for subsidiary association without using specific interaction coefficients is discussed, and it is concluded that this cannot be done in a completely satisfactory way. Measurements in mixed solvents are used to determine association parameters for the complex TlCl.



1966 ◽  
Vol 19 (6) ◽  
pp. 915 ◽  
Author(s):  
JB Macaskill ◽  
MH Panckhurst

The solubility of thallous chloride has been measured in solutions of hydrochloric acid, caesium chloride, caesium perchlorate, barium chloride, and in various mixtures of sodium chloride and sodium perchlorate. These measurements are analysed to give the association constant for thallous chloride, paying particular attention to ionic activity coefficient formulae. It is shown that an activity coefficient expression which assumes no specific interactions between free ions is unsatisfactory in contrast to an expression which assumes such interactions. The consequences of this are discussed.



1964 ◽  
Vol 17 (5) ◽  
pp. 522 ◽  
Author(s):  
JB Macaskill ◽  
MH Panckhurst

The solubility of thallous chloride has been measured in sodium chloride and sodium perchlorate solutions at an ionic strength less than 0 1M. The association constant of thallous chloride has been determined from these measurements using two different types of ionic activity coefficient expression, one of them incorporating Br�nsted's principle of specific interaction. The method for determining the association constant gives all the parameters in the treatment but the two activity coefficient expressions give different sets of parameters. These are discussed.



1968 ◽  
Vol 22 ◽  
pp. 435-443
Author(s):  
Terje Østvold ◽  
O. Hassel ◽  
Torbjörn Lindblom ◽  
Charles Larsen ◽  
Carl Th. Pedersen ◽  
...  


1962 ◽  
Vol 15 (3) ◽  
pp. 409 ◽  
Author(s):  
RJL Martin

The ion association constants KA=[M+A-]/[M+][A-] which have been measured conductimetrically at 105 7 �C in acetic acid are : perchloric acid 0.0644 X 106, sodium perchlorate 0.1346 x 106, and sodium acetate 0.752 x 106. The parameters 6, centre to centre distance between the ions at contact, which were calculated from Bjerrum's formula, are : perchloric acid 4.52 Ǻ, sodium perchlorate 4.20 Ǻ, and sodium acetate 3.61 Ǻ. The autoprotolysis constant, K = [H2+ Ac][Ac-]= 1.17 x 10-19, was calculated from the specific conductivity of acetic acid at 105.7 �C. The acetic acidium acetate ion pairs were calculated to be 100.0% dissociated.



1972 ◽  
Vol 25 (2) ◽  
pp. 317 ◽  
Author(s):  
CY Chan ◽  
MH Panckhurst

In an attempt to resolve discrepancies between association constants obtained from solubility and absorbance measurements for thallium(1) chloride and bromide the explicit assumptions used in the various analyses have been considered in detail. It is shown that the discrepancies can be accounted for in part by considering the activity coefficient of the complex TlCl or TIBr, and, more importantly, by allowing for the presence of small amounts of higher complexes in analysing absorbance data. It is also shown, in determining association constants using a specific ionic activity coefficient expression, that uncertainties in some interaction coefficients reduce the usefulness of our solubility measurements in non-common ion salts. In particular, it is concluded, using the specific ionic interaction coefficient expression, that association constants can at present only be arrived at from solubility measurements by specifying arbitrary interaction coefficients for thallium(1) and halide ions; and to obtain association constants using a non-specific ionic activity coefficient expression it is necessary to assume unnecessarily arbitrary subsidiary association reactions as well as an arbitrary value for the activity coefficient parameter B.



1972 ◽  
Vol 25 (2) ◽  
pp. 311 ◽  
Author(s):  
CY Chan ◽  
MH Panckhurst

Measurements are reported of the optical absorbance of aqueous solutions of thallium(I) bromide in mixture with other electrolytes a t 25°. These measurements are similar to those previously reported1 for thallium(I) chloride and are used in conjunction with two different types of ionic activity coefficient expressions to investigate association of thallium(I) bromide. Both types of expression give a reasonable description of the experimental results but there is the same disagreement with the analysis of solubility measurements found for thallium(1) chloride.



1969 ◽  
Vol 22 (2) ◽  
pp. 317 ◽  
Author(s):  
JB Macaskill ◽  
MH Panckhurst

Precise measurements are reported of the optical absorbance of aqueous solutions of thallium(I) chloride in mixture with other electrolytes at 25�. Two types of activity coefficient expressions are used to analyse the measurements in terms of association of thallium(I) chloride. The method of analysis is similar to that used for solubility measurements1-3 and the different types of measurements lead to different values for the association constants.





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