SVIBOR - Project code: 1-07-112

MINISTRY OF SCIENCE AND TECHNOLOGY

Strossmayerov trg 4, HR - 10000 ZAGREB
tel.: +385 1 459 44 44, fax: +385 1 459 44 69
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Project code: 1-07-112

PROPERTIES OF ELECTROLYTES IN MIXED SOLVENTS

Main researcher: MEKJAVIĆ, IVICA (30354)

Assistants

VIŠIĆ, MARIJA (91231)
TOMINIĆ, IVO (75944)
TOMAŠ, RENATO (900689)

Type of research: basic
Duration from: 01/01/91. to 12/15/95.

Papers on project (total): 7
Papers on project quoted in Current Contents: 3

Institution name: Tehnološki fakultet, Split (11)
Department/Institute: Laboratory of Physical Chemistry
Address: 21000 Split, Teslina 10
City: 21000 - Split, Croatia

Communication: Phone: 385 (0)21 341633; Fax: 385 (0)21 341624

Summary: Association constant (KA), ion-pair radius (R), and limiting molar conductivity (Lo) will be determined based on conductivity measurements of NaBr electrolyte in tert. butanol-water and 2-butanol-water mixtures in the temperature range 15-35řC, and by applying various conductivity equations. From the values of KA obtained at different temperatures the thermodynamic quantities will be established for ion-association reaction Na+ and Br-. The influence of dielectric constant and alcohol component on these quantities will be determined. From electromotive force (EMF) measurements of the concentration cell with transfer in tert. butanol-water mixtures in the temperature range 15-35řC the stability constants will be established for various cadmium-chloride complexes and also the thermodynamic quantities for the reactions forming these complexes. From electromotive force measurements of chemical cells without transfer with Cd-chloride in the same mixtures and in the same temperature range the standard electromotive force of the cell will be determined. These data will enable to obtain the thermodynamic quantities which indicate the acid-base properties of the solvents and their structure.

Keywords: Mixed solvents, conductivity, sodium bromide, ion-association, thermodynamic quantities, potentiometry, cadmium chloride complexes, stability constants.

Research goals: The purpose of investigations is to gain an insight into the ion-association reactions of 1-1 type electrolyte and the reactions forming different complexes of 2-1 type electrolyte in mixed solvents with lower dielectric constants containing water as one component. The association reaction of HBr electrolyte was analyzed by taking into account the conductivity measurements in water-butanol isomers mixtures, and analogous investigations have been initiated with NaBr electrolyte. The aim is to find out more about the suitability of using particular theoretical conductivity equations for calculating the limiting molar conductivity of electrolytes, the association constants and the ion distance within the ion pairs; then, from the obtained parameter, to decide on the mechanism of the ion transfer, the thermodynamics of the association reaction and on the character of the ion pairs. Finally, the aim is to learn about the influence on these parameters which is exerted by the dielectric constant of the solvents and by the organic component. The complexation reaction was studied with Cd-chloride electrolyte in 2-propanol-water and acetone-water mixtures, and measurements have been started with tert. butanol-water mixtures. The aim is to determine the stability constants for the cadmium complexes formed, and to estimate the influence of the organic component on the obtained parameters. The results obtained from investigations of the complexation reaction will then make it possible, along with some additional measurements, to establish the thermodynamic quantities for the reaction with transfer of Cd-chloride electrolyte from the water into the mixed solvents under investigation, all of which can assist in understanding their structure.

Other information about the project.


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Last update: 10/09/95
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