Solutions Of Cadmium Iodide Research Articles

Velocity correlations in aqueous electrolyte solutions from diffusion, conductance and transference data. Application to concentrated solutions of cadmium iodide

Tracer-diffusion and intradiffusion coefficients have been measured for the Cd and Cl ion constituents and for water molecules in aqueous solutions of cadmium chloride in the concentration range 0.1–5.8 mol dm–3 at 298.15 K. These measured coefficients have been combined with transport data from other sources to calculate velocity cross-correlation coefficients (VCCs). In contrast to a fully dissociated 1 : 2 salt such as magnesium chloride, the VCCs for CdCl2 show much greater positivity, and in particular the anion–anion VCC is positive over the whole concentration range. An explanation for the negative transference numbers in concentrated CdCl2 solutions is offered using the linear-response-theory formalism.

Transport in aqueous solutions of Group IIB metal salts. Part 7.—Measurement and prediction of isotopic diffusion coefficients for iodide in solutions of cadmium iodide

Isotopic diffusion coefficients for iodide have been measured in aqueous solutions of cadmium iodide over the concentration range 0.1–1.0 mol dm–3, using the diaphragm cell technique. The iodide diffusion coefficients are shown to decrease smoothly but steeply from the infinite dilution value of 2.046 × 10–5 cm2 s–1 to less than half that value in the concentration range above 0.1 mol dm–3. This remarkable decline has been assigned to the presence of complexes of the type CdI+2–xx(x= 1, 2, 3, 4). The irreversible thermodynamic analysis developed previously for cadmium diffusion in this same system (part 4) has been extended to include isotopic diffusion of labelled ligands on multiply substituted complexes. Using this analysis the observed iodide diffusion coefficients have been predicted within close limits over the whole concentration range up to ≈ 0.5 mol dm–3.

Transport in aqueous solutions of group IIB metal salts (298.15 K). Part 4.—Interpretation and prediction of isotopic diffusion coefficients for cadmium in dilute solutions of cadmium iodide

A method for predicting isotopic diffusion coefficients for component ions in a self-complexed electrolyte has been developed. In an irreversible thermodynamic analysis the diffusion coefficient has been shown to be a function of the mobility coefficients of the free ion and its complexes together with the interionic coupling coefficients between labelled and unlabelled species. It is shown that these coefficients may be evaluated by an extension of the methods developed earlier to predict isothermal transport in such systems. Cadmium ion diffusion coefficients in aqueous cadmium iodide, Daa, have been predicted (0.003–0.10 mol dm–3). These describe the maximum anticipated experimentally. Observed and calculated Daa agree to within 3 % at 0.1 mol dm–3.

Ultrasonic Velocities in Aqueous Electrolyte Solutions

IN a recent communication, Mr. S. V. Subrahmaniam1 has reported measurements of ultrasonic velocities in aqueous solutions of cadmium iodide and mercuric chloride. I have made a detailed investigation of the variation of ultrasonic velocities in a number of aqueous solutions of electrolytes with concentration and temperature. The electrolytes that show the rather unusual behaviour of decreasing sound velocity with increasing concentration are the following: (1) cadmium bromide, (2) cadmium iodide, (3) zinc iodide, (4) strontium iodide, (5) lead acetate, (6) uranyl chloride, and (7) uranyl nitrate. The detailed results were published2,3; the conclusions reached in those studies are as follows :

The Thermodynamics of Bi-univalent Electrolytes. VI. Solutions of Cadmium Iodide from 5 to 40°

The Thermodynamics of Bi-univalent Electrolytes. VI. Solutions of Cadmium Iodide from 5 to 40°