ISSN:
1572-8927
Keywords:
Apparent molal volumes
;
partial molal volumes
;
density
;
bolaform electrolytes
;
H2O
;
D2O
;
structure effect
;
cavity effect
;
cation pairing
;
volumes of transfer
;
solvent isotope effect
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Abstract The apparent,φ v, and partial, $$\bar V$$ 2, molal volumes of a series of homologousbis-tetraalkylammonium bromides have been determined in H2O and D2O at 25°C from precision density measurements carried out with a buoyancy densimeter and a dilatometer. The Debye-Hückel theoretical limiting slope forφ v and $$\bar V$$ 2 as a function of the square root of molar concentration is approached for all of the salts studied. the concentration dependence ofφ v and $$\bar V$$ 2 is anomalously large and negative in both solvents, with the deviations being less negative in D2O than in H2O. The bolaform salts have larger $$\bar V$$ 2 o values in H2O than in D2O, contrary to the observed behavior of R4NX salts. Possible origins of the solvent isotope effects observed are discussed in terms of structural and cavity contributions to the measured volumes. A comparison of thermodynamic transfer functions (H2O→D2O) for Et4N Br and the corresponding bolaform analog appropriate in the consideration of cation-cation pairing of Et4N+ ions shows inconclusive evidence for the support of the cation pair theory.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00648227
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