Special features of solubility isotherms of salt hydrates have been observed, from which the evidence of strong organization of saturated solutions of hydrates may be deduced. Often observed low contents of the non saturating component in the eutonic solution limiting the crystallization branch of hydrated salts is put into connection with this result. The composition of the respective eutonic solutions exhibits a correlation with the hydration entropy of the ions present in the ternary saturated solution.

A quantity has been introduced, whose dependence on the composition along the branches of the solubility isotherms of ternary systems consisting of two salts with a common ion and water exhibits breaks, which can be explained by the introduction of a previously unobserved configuration of the ternary saturated solution. In the respective region, a saturated solution in a ternary system may undergo second-order phase transitions to achieve specific configurations that are not derived from the structure of the binary saturated solution of the particular solute. It is assumed that further study of this phenomenon could contribute to a better understanding of the processes occurring in concentrated electrolyte solutions.

This study deals with the hydrates of double selenates of the type M2(I)M(II)(SeO4)2 . XH2O (x = 2 or 6) from the point of view of the effect of the M(I)(M(I)= K, Rb, Cs, Tl, NH4) and M(II) (M(II) = Mg, Zn, Cd, Mn, Co, Ni, Cu) cations on the water molecules in-the coordination sphere of the bivalent metal. The bonds of the water molecules were studied on the basis of the bands of the "wagging" libration modes of the water molecules, and the bands of the stretching vibrations in the infrared molecular spectrum, and using thermal analysis. According to the study of "wagging" libration modes the deformation of the coordination sphere of the hexaaqua cations [M(II)(H2O)6]2+ increases with the decreasing radius of cation M+ and with the increasing radius of cation M2+, and thus the tendency to form dihydrates of the studied double selenates also increases. This dependence corresponds with the thermal decomposition of the hexahydrates to dihydrates. Thermal decomposition of dihydrates to the anhydrous salts is determined primarily by the strength of the hydrogen bonds between the test anions and the water molecules, once again affected by the two types of cations. The NH4+, Tl+, Cu2+, and Ni2+ cations specifically affect the thermal decomposition of the hydrates of the double selenates.

The energy changes associated with the formation of double selenates of the schoenite type were studied. By using the Filippov eutonic method, the ΔG° values were obtained directly for the formation of the (NH4)2M(SeO4)2.mH2O salts with M = Mn, Co, Ni, Zn and Cd and m = 6 except for Cd, for which m = 2. The ΔG° values are comparable with those for the analogous potassium salts and they lie within the range of –13.9 to –45.9 kJ mol-l. The fact that the final ΔG° value is primarily affected by the solubilities of the components and of the compound forming was verified for the examined (NH4)2SeO4-MIISeO4-H2O systems as well.

The solubility diagrams in the [(CH3)4N]2SeO4-MgSeO4-H2O and [(CH3)4N]2SeO4-NiSeO4-H2O systems at 25-degrees-C were studied. Basing on the results obtained the compounds [(CH3)4N]2Mg3(SeO4)4.21H2O, [(CH3)4N]2Mg2(SeO4)3.12H2O, and [(CH3)4N]2Ni(SeO4)2.9H2O, which were not described in the literature till now, were prepared. On the basis of the infrared and electronic spectra, thermal analysis, X-ray powder diffractometry, and the measurement of the magnetic susceptibility the bonding relations in these substances were studied. It was found that the octahedral [M(H2O)6]2+ and tetrahedral [(CH3)4N]+ cations and the selenate anions SeO42- are the fundamental structural units in these substances.

The heterogeneous K2SeO4-MIISeO4-H2O system (MII = Mn, Co, Ni, Cu, Zn) at 298 K was studied using the Filippov eutonic method, yielding values for the change in the standard Gibbs energy ΔG0 for the formation of double selenates in the range 16.2-30.3 kJ/mol. It follows from the ΔG0 values that, in systems without strong interactions in the liquid phase, the formation of poorly soluble double selenates from readily soluble selenates is energetically most favourable.

The energy conditions for the formation of the compounds under the conditions of heterogeneous equilibrium were studied using the Filippov eutonic method, permitting the ΔG° values for the reactions leading to the formation of the above double selenates to be obtained directly. The values obtained, which varied in the range -17.8 to -24.4 kJ mol-1, were correlated with the solubilities of the compounds formed and the selenates M2SeO4. The interaction M2SeO4-MgSeO4 in the liquid phase was also studied.

Zeitschrift für ChemieVolume 30, Issue 6 p. 227-228 Kurze Originalmitteilungen Die Beziehung zwischen der Beständigkeit der Hydrogenphosphite und der Zusammensetzung des Systems Phosphit-phosphorige Säure-Wasser Miroslav Ebert, Miroslav Ebert Karls-Universität, Institut für anorganische Chemie, Prag, ČSFRSearch for more papers by this author Miroslav Ebert, Miroslav Ebert Karls-Universität, Institut für anorganische Chemie, Prag, ČSFRSearch for more papers by this author First published: Juni 1990 https://doi.org/10.1002/zfch.19900300621AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume30, Issue6Juni 1990Pages 227-228 RelatedInformation

Zeitschrift für ChemieVolume 29, Issue 6 p. 220-221 Kurze Originalmitteilungen Löslichkeitsuntersuchung in den Systemen MI2SeO4-MgSeO4-H2O (MI = Li, NH4 und TI) bei 25°C Pavel Vojtíšek, Pavel Vojtíšek Karls-Universität, Institut für anorganische Chemie, 12840 Prag, ČSSRSearch for more papers by this authorMiroslav Ebert, Miroslav Ebert Karls-Universität, Institut für anorganische Chemie, 12840 Prag, ČSSRSearch for more papers by this author Pavel Vojtíšek, Pavel Vojtíšek Karls-Universität, Institut für anorganische Chemie, 12840 Prag, ČSSRSearch for more papers by this authorMiroslav Ebert, Miroslav Ebert Karls-Universität, Institut für anorganische Chemie, 12840 Prag, ČSSRSearch for more papers by this author First published: Juni 1989 https://doi.org/10.1002/zfch.19890290621Citations: 1AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article.Citing Literature Volume29, Issue6Juni 1989Pages 220-221 RelatedInformation

Zeitschrift für ChemieVolume 29, Issue 7 p. 265-266 Kurze Originalmitteilungen Untersuchung in den Systemen MnSeO4-M12ScO4-H2O (M1 = K, NH4, Rb) bei 25°C Pavel Vojtisek, Pavel Vojtisek Karls-Universität, Institut für anorganische Chemie, 128 40 Prag, ČSSRSearch for more papers by this authorMiroslav Ebert, Miroslav Ebert Karls-Universität, Institut für anorganische Chemie, 128 40 Prag, ČSSRSearch for more papers by this authorZuzana Sieglová, Zuzana Sieglová Karls-Universität, Institut für anorganische Chemie, 128 40 Prag, ČSSRSearch for more papers by this author Pavel Vojtisek, Pavel Vojtisek Karls-Universität, Institut für anorganische Chemie, 128 40 Prag, ČSSRSearch for more papers by this authorMiroslav Ebert, Miroslav Ebert Karls-Universität, Institut für anorganische Chemie, 128 40 Prag, ČSSRSearch for more papers by this authorZuzana Sieglová, Zuzana Sieglová Karls-Universität, Institut für anorganische Chemie, 128 40 Prag, ČSSRSearch for more papers by this author First published: Juli 1989 https://doi.org/10.1002/zfch.19890290724Citations: 1AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article.Citing Literature Volume29, Issue7Juli 1989Pages 265-266 RelatedInformation

ChemInformVolume 20, Issue 46 Physical Inorganic Chemistry ChemInform Abstract: The Systems MnSeO4-M(I)2SeO4-H2O (M(I): K, NH4, Rb) at 25 ° C P. VOJTISEK, P. VOJTISEK Inst. Anorg. Chem., Karls-Univ., 128 40 Prag, CSSRSearch for more papers by this authorM. EBERT, M. EBERT Inst. Anorg. Chem., Karls-Univ., 128 40 Prag, CSSRSearch for more papers by this authorZ. SIEGLOVA, Z. SIEGLOVA Inst. Anorg. Chem., Karls-Univ., 128 40 Prag, CSSRSearch for more papers by this author P. VOJTISEK, P. VOJTISEK Inst. Anorg. Chem., Karls-Univ., 128 40 Prag, CSSRSearch for more papers by this authorM. EBERT, M. EBERT Inst. Anorg. Chem., Karls-Univ., 128 40 Prag, CSSRSearch for more papers by this authorZ. SIEGLOVA, Z. SIEGLOVA Inst. Anorg. Chem., Karls-Univ., 128 40 Prag, CSSRSearch for more papers by this author First published: November 14, 1989 https://doi.org/10.1002/chin.198946010Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume20, Issue46November 14, 1989 RelatedInformation

Zeitschrift für ChemieVolume 27, Issue 9 p. 345-346 Kurze Originalmitteilungen Löslichkeitsuntersuchung in den Systemen (NH4)2SeO4-MIISeO4-H2O (MII = Zn, Cd) und K2SeO4-CdSeO4-H2O bei 25°C Pavel Vojtišek, Pavel Vojtišek Karls-Universität, Institut für anorganische Chemie, 128 40 Prag, ČSSRSearch for more papers by this authorMiroslav Ebert, Miroslav Ebert Karls-Universität, Institut für anorganische Chemie, 128 40 Prag, ČSSRSearch for more papers by this author Pavel Vojtišek, Pavel Vojtišek Karls-Universität, Institut für anorganische Chemie, 128 40 Prag, ČSSRSearch for more papers by this authorMiroslav Ebert, Miroslav Ebert Karls-Universität, Institut für anorganische Chemie, 128 40 Prag, ČSSRSearch for more papers by this author First published: September 1987 https://doi.org/10.1002/zfch.19870270920Citations: 2AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Literatur 1 Meyer, J.; Aulich, N.: Z. anorg. Chem. 172 (1928) 321 10.1002/zaac.19281720122 CASGoogle Scholar 2 Hill, A. E.; Soth, G. C.; Ricci, J. E.: J. Amer. chem. Soc. 62 (1940) 2717 10.1021/ja01867a033 CASGoogle Scholar 3 Vojtišek, P.; Ebert, M.: Z. Chem. 25 (1985) 414 10.1002/zfch.19850251122 CASWeb of Science®Google Scholar 4 Vojtišek, P.; Ebert, M.: Z. Chem., im Druck Google Scholar 5 Vojtišek, P.; Ebert, M.: Z. Chem., im Druck Google Scholar 6 Vojtišek, P.; Ebert, M.: Z. Chem., im Druck Google Scholar 7 Lawrence, R. W.; King, G. M.: J. Amer. chem. Soc. 60 (1938) 1987 10.1021/ja01275a074 CASGoogle Scholar 8 Welton, R. C.; King, G. B.: J. Amer. chem. Soc. 61 (1939) 1251 10.1021/ja01874a072 CASGoogle Scholar 9 King, G. B.; Beckman, W. A.: J. Amer. chem. Soc. 67 (1945) 857 10.1021/ja01221a049 CASWeb of Science®Google Scholar 10 Přibil, R.: Komplexometrie, Praha, SNTL, 1977 Google Scholar 11 Blanka, B.; Hudec, P.; Toužin, J.: Collect. czechoslov. chem. Commun. 28 (1963) 3434 10.1135/cccc19633434 CASWeb of Science®Google Scholar 12 Schreinemakers, F. A. H.: Z. physik. Chem. [Leipzig] 55 (1906) 71 CASWeb of Science®Google Scholar 13 Montgomery, H.: Acta crystallogr. [Copenhagen] B 36 (1980) 440 10.1107/S0567740880003445 CASWeb of Science®Google Scholar 14 Monge, A.; Gitierrez-Puebla, E.: Acta crystallogr. [Copenhagen] B 37 (1981) 427 10.1107/S0567740881003166 CASWeb of Science®Google Scholar 15 Peytavin, S.; Philippot, E.; Lindqvist, O.: Cryst. Struct. Commun. 2 (1973) 163 CASGoogle Scholar Citing Literature Volume27, Issue9September 1987Pages 345-346 ReferencesRelatedInformation

Ammonium phoaphates belong among principal compounds of rnulticomponent liquid fertilizers and thus this study has been directed toward agrochernical application. The system NH4H2PO4-(NH4) 2H2PO4- (NH4)2H2P2O7- (NH4)3 H2P3O10- (NH4) 3PO4-(NH4)4) 4P2O7-(NH4)5P3O10-H2O was studied in which the pH of saturated solutions varies from 5 to 8. The solubility was studied in the partial pseudoternary systems. The experimental temperatures were selected immediately above the corresponding cryohydratic points, from 0 to -8 °C, The results were discussed using a computer. The procedure used makes it possible to find a smoothing equation for each branch of the solubility diagram at issue. Simultaneously, a set of coefficienta Q related to the ideality of the respective solutions was found, From practical point of view, it can be seen from the results obtained that the highest concentrations of agrochemically effective components(nitrogen and phosphorus pentaoxide) are attained in saturated solutions containing triphosphate with a nutritional value of more than 50%.