Premium
Temperature dependence of activation energies for self‐diffusion of water and of alkali ions in aqueous electrolyte solutions. A model for ion selective behavior of biological cells
Author(s) -
Talekar Subhash V.
Publication year - 2009
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.560120741
Subject(s) - chemistry , ion , electrolyte , diffusion , aqueous solution , activation energy , self diffusion , kinetic energy , alkali metal , thermodynamics , chemical physics , range (aeronautics) , atmospheric temperature range , materials science , organic chemistry , physics , self service , electrode , marketing , quantum mechanics , business , composite material
Abstract Samoilov's kinetic hydration model, based on short‐range interactions for aqueous electrolyte solutions, is critically examined. The treatment suffers from a basic assumption that the activation energy for self‐diffusion of ion in water ( E i (H 2 O) ) is equivalent to the activation energy for self‐diffusion of water from near an ion ( E H 2 O( i ) ). The change in activation energy for self‐diffusion of water (Δ E ) in the presence of an ion is also obtained under that assumption. A simple approach is outlined, using experimental diffusion data at different temperatures, which shows that ( 1 ) E i (H 2 O)is not equal to E H 2 O( i )except at 12°C for Li + , 28°C for Na + , and 44°C for K + , and ( 2 ) Δ E is obtained directly without Samoilov's assumption. The present approach shows that “positive hydrators” and “negative hydrators” interchange their roles along the temperature scale in terms of the sign of Δ E . This property of change in the sign of Δ E with temperature for a given ion may serve as a model to the more complex ion selective behavior of biological cells.