STUDIES OF EMF CELLS WITH LIQUID JUNCTIONS BETWEEN DIFFERENT SOLVENTS.
Item
-
Title
-
STUDIES OF EMF CELLS WITH LIQUID JUNCTIONS BETWEEN DIFFERENT SOLVENTS.
-
Identifier
-
AAI8614658
-
identifier
-
8614658
-
Creator
-
BERNE, ANNA.
-
Contributor
-
Orest Popovych
-
Date
-
1986
-
Language
-
English
-
Publisher
-
City University of New York.
-
Subject
-
Chemistry, Analytical
-
Abstract
-
Liquid-junction potentials, E(,j), between electrolyte solutions in water and methanol-water solvents were interpreted using both existing equations and a new formulation developed here. The E(,j)'s were evaluated from the e.m.f. of cells with liquid junction, by considering the contribution of the transfer free energies, transport numbers, and activity coefficients of all the species crossing the junction. Cells with and without salt bridges were studied. The E(,j) was formally divided into E(,j) and E(,j's), which account, respectively, for the transport of the ions and the solvent molecules across the interface. An improved formulation for E(,j) was developed which accounts for the variation of the transport numbers of the ions crossing the boundary with the solvent composition across the diffusion layer. E(,j's) was estimated for junctions between pairs of HCl solutions, pairs of NaCl solutions, and for junctions with a concentrated aqueous KCl salt bridge. E(,j's) values between water and methanol-water solvents showed a dependence on the content of methanol, the concentration of the electroactive species and the nature of the current-carrying species. Literature data from pH-cells with liquid-junction in methanol-water media were interpreted.;A new method for estimating transfer activity coefficients of single ions was tested for tetraalkylammonium cations using e.m.f. cells with salt bridge of tetraalkylammonium perchlorate (RClO(,4)) between pairs of the following dipolar aprotic solvents: acetonitrile, N,N-dimethylformamide, dimethylsulfoxide, and propylene carbonate. Subsequently, a two-step procedure was developed, in which concentration-dependent log(,m) values of the tetraalkylammonium perchlorate ions obtained in the first step were used to interpret e.m.f. measurements of cells with a salt bridge of tetraalkylammonium picrate (RPi) in order to estimate transfer activity coefficients of the picrate ion.;A saturated solution of tetraphenylarsonium tetraphenylborate (Ph(,4)AsBPh(,4)) in DMSO and later in DMF was used as a salt-bridge between pairs of dipolar aprotic solvents in e.m.f. cells used for estimating transfer activity coefficients, of the sodium ions, log(,m Na). The new values of log(,m Na) were compared with the literature values, including those obtained with other salt-bridge electrolytes, thus allowing for the evaluation of the performance of Ph(,4)AsBPh(,4) as an "ideal" salt-bridge electrolyte.
-
Type
-
dissertation
-
Source
-
PQT Legacy CUNY.xlsx
-
degree
-
Ph.D.
-
Program
-
Chemistry
