DEVELOPMENT OF AN ELECTROCALORIMETRY SYSTEM

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Solution equilibria have been studied by potentiometry using an electrode as a sensor and by various spectroscopic methods. Recently, an on-line controlled high-precision calorimetry, with precision as high as that of potentiometry, has been used studying solution equilibria. We have developed an on-line controlled calorimetry system, and used it particularly for studying metal-ion complexation in nonaqueous solution. In general, potentiometry cannot be used in nonaqueous solutions, as suitable electrodes are hardly available in the solvent. Precise calorimetry can therefore expand the extent of research area of solution chemistry. In order to understand reactions in solution, calorimetry other than that for simple complexation reaction may be necessary. Therefore, in this project, we tried an electrocalorimetry, which may afford us information on the enthalpy change of an electron transfer or redox reaction. This is our first trial for measuring the heat evolved due to electrode reactions, and we disigned and made new cells for the measurements. As a heat of reaction is consisted of heats of both electron transfer and complexation, a heat evolved at a reaction stage is a complicated function of concentrations of related species, and the amount of electron transfer. Therefore, the analysis of measured heat is not successful at the present stage. We will continue this project and establish the method of analysis to extract useful information on electron transfer.