Cadmium selenites

Chukhlantsev [56CHU] prepared cadmium selenite by mixing a 0.1 M sodium selenite solution with the equivalent amount of a cadmium chloride solution. The product was amorphous. Chemical analysis confirmed the 1 1 ratio between Cd and Se(lV). The solubility of the specimen in dilute solution of nitric or sulphuric acid was measured at 293 K. The data have been recalculated as described in Appendix A, [56CHU]. The result for 

Toropova [57TOR] measured the shift of the polarographic half-wave potential of Cd in 0.15 to 0.50 M sodium selenite solutions. The solutions also contained 

but it is not possible to find out from the text whether the sodium ion concentration or the ionic strength was kept constant. As no experimental data are provided to support the reported equilibrium constant for the proposed complexation according to the reaction  

Bakeeva, Buketov, and Pashinkin [68BAK/BUK3] measured the equilibrium pressure of Se02(g) above CdSe03(P or 1) by the dew point method. Their primary data have been recalculated as described in [71PAS/ARO] in Appendix A with the following results  

The extrapolation of the data to standard conditions was made with the estimated heat capacities in [73BAR/KNA]. The derived standard enthalpy and entropy values are Af//° (CdSe03, (3, 298.15 K) = - (608.3 + 8.4) kJ-mol and (CdSeOs, p, 298.15 K) = (108.2 8.0) J K -mol. The recalculation performed by Pashinkin et al. [71PAS/ARO] with another set of auxiliary data agrees within the uncertainties with the result obtained by the review. The extrapolated enthalpy of formation of CdSeOs from the high temperature measurements has been given zero weight. 

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The solubility product of CdSe03(am) determined in [56CHU] yields 5°(CdSe03, am, 298.15 K) = (127.4+13.0) J-K -mor, while the extrapolated value (108.2 J-K -mol ) corresponds to log, (CdSe03, cr, 298.15 K) = - (8.6 0.6). In order to make log, K° < - 9.6, the entropy of CdSe03(cr) should exceed about 130 J-K -mol. With the experimental data at hand, the inconsistency between the entropy of cadmium selenite obtained from the high temperature data and the solubility measurement cannot be resolved. The review makes the selection ... 

Table A-53 Measured enthalpies of dissolution of zinc and cadmium selenites in H2S04(aq, 1 50) and mercury selenites in HCl(aq, 1 35). The enthalpies of formation have been estimated from these data. The uncertainties stem from the original publication. The data for the compounds provided with an asterisk are given for information only as they do not seem to form under normal aqueous conditions cf. phase diagram studies reported in Chapter V).

SEL/LES5] Selivanova, N. M., Leshchinskaya, Z. L., Strel tsov, 1. S., Fleat of formation of cadmium selenite, Zh. Fiz. Khim., 37, (1963), 668-670, in Russian, English translation in [63SEL/LES6]. Cited on pages 273,472,473. 

BAK/BUK4] Bakeeva, S. S., Buketov, E. A., Pashinkin, A. S., Dissociation pressure of cadmium selenite, Russ. J. Inorg. Chem., 13, (1968), 927-928. From a citation in this Bibliography... 

Table A-53 Measured enthalpies of dissolution of zinc and cadmium selenites in H2S04(aq, 1 50) and mercury selenites in HCl(aq, 1 35). 491...

Ca5Si6017 3H20 5-CALCIUM 6-SILICATE 3-HYDRATE 468 CdSe03 CADMIUM SELENITE 505... 

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