Summary
The negative stability limit of AgI shifts with increasing concentrations of the solvents ethanol, acetone and glycine in water asymptotically to a lower limiting pAg value. The main shift occurs in 10 mol% of acetone and ethanol and 1.8 mol% of glycine from pAg 6.2 in water to 3.0, 4.2 and 3.0 resp. In solutions of the same solvent content the coagulation values remain practically equal to the coagulation values in pure water, the change being less than 0.2. In the negative stability region from pI 1 to the negative stability limit in the water solvent mixture the coagulation values of cations of valency 1,2 and 3 are practically constant and independent of the activity of the potential determining ion in excess. The negative limit in 10 to 15 mol% acetone and ethanol in the AgBr system is 4.7 and 5.4 resp. The present results were shown to confirm well the ion exchange theory of coagulation.
Zusammenfassung
Die negative Stabilitätsgrenze von AgI verlagert sich mit steigenden Konzentrationen der Lösungsmittel Äthylalkohol, Aceton und Glycin in Wasser asymptotisch zu niedrigeren pAg-Grenzwerten. Die Hauptverschiebung findet in 10 Mol%igem Aceton und Äthylalkohol und 1,8 Mol%igem Glycin von pAg 6,2 in Wasser zu 3,0, 4,2 und 3,0 resp. statt. In Lösungen vom selben Gehalt bleiben die Koagulationswerte praktisch gleich denen im reinen Wasser; die Änderung ist kleiner als 0,2. Im negativen Stabilitätsbereich von pI 1 zur negativen Stabilitätsgrenze in Wasser-Lösungsmittel-Gemischen sind die Koagulationswerte von Kationen der Valenz 1–3 praktisch konstant und unabhängig von der Aktivität des potentialbestimmenden Ions. Die negative Grenze ist in 10–15 Mol% Aceton und Äthyläther im AgBr-System 4,7 und 5,4 resp. Diese Resultate bestätigen gut die Ionenaustauschtheorie der Koagulation.
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References
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Contribution No. 102 from the Department of Physical Chemistry, Faculty of Science, University of Zagreb, Zagreb, Yugoslavia.
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Mirnik, M., Flajšman, F. & Težak, B. The negative activity limit of stability and the coagulation values of silver halides. Kolloid-Z.u.Z.Polymere 185, 138–144 (1962). https://doi.org/10.1007/BF01542349
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DOI: https://doi.org/10.1007/BF01542349