Universität zu Köln

Mohanakumar, Shilpa ORCID: 0000-0001-7098-0065, Kriegs, Hartmut, Briels, W. J. and Wiegand, Simone ORCID: 0000-0001-6333-1956 (2022). Overlapping hydration shells in salt solutions causing non-monotonic Soret coefficients with varying concentration. Phys. Chem. Chem. Phys., 24 (44). S. 27380 - 27388. CAMBRIDGE: ROYAL SOC CHEMISTRY. ISSN 1463-9084

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Abstract

We investigate the thermodiffusive properties of aqueous solutions of sodium iodide, potassium iodide and lithium iodide, using thermal diffusion forced Rayleigh scattering in a concentration range of 0.5-4 mol kg(-1) of solvent, large enough to deal with associated salts, and a temperature range of 15 to 45 degrees C. All systems exhibit non-monotonic variations of the Soret coefficient S-T with concentration, with a minimum at one mol kg(-1) of solvent in all three cases. We take this as an indication that the relevant length and energy scales are very similar in all cases. On this basis we develop an intuitive picture in which the relevant objects are the fully hydrated salt molecules, including all water molecules that behave differently from bulk water. Preliminary, somewhat sketchy calculations indicate that indeed Soret coefficients begin to rise beyond concentrations where the fully hydrated particles are randomly close packed. Indications are given as to why the model will fail at large concentrations.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Mohanakumar, Shilpa UNSPECIFIED orcid.org/0000-0001-7098-0065 UNSPECIFIED Kriegs, Hartmut UNSPECIFIED UNSPECIFIED UNSPECIFIED Briels, W. J. UNSPECIFIED UNSPECIFIED UNSPECIFIED Wiegand, Simone UNSPECIFIED orcid.org/0000-0001-6333-1956 UNSPECIFIED
URN:	urn:nbn:de:hbz:38-674988
DOI:	10.1039/d2cp04089a
Journal or Publication Title:	Phys. Chem. Chem. Phys.
Volume:	24
Number:	44
Page Range:	S. 27380 - 27388
Date:	2022
Publisher:	ROYAL SOC CHEMISTRY
Place of Publication:	CAMBRIDGE
ISSN:	1463-9084
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language THERMAL-DIFFUSION COEFFICIENTS; AQUEOUS-SOLUTIONS; TEMPERATURE-DEPENDENCE; ELECTROLYTE-SOLUTIONS; WATER; IONS; POTASSIUM; EXCHANGE; CHLORIDE; HALIDES Multiple languages Chemistry, Physical; Physics, Atomic, Molecular & Chemical Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/67498