DEVELOPMENT OF AN ELECTROCALORIMETRY SYSTEM

溶液平衡已经通过使用电极作为传感器的电位测定法和通过各种光谱方法进行了研究。近年来，一种在线控制的高精度量热法已被用于研究溶液平衡，其精度可与电位滴定法相媲美。我们开发了一个在线控制量热系统，并将其专门用于非水溶液中金属离子络合反应的研究。通常，电位法不能用于非水溶液中，因为在溶剂中几乎没有合适的电极。因此，精确的量热法可以扩大溶液化学的研究范围。为了理解溶液中的反应，除了简单络合反应之外，量热法可能是必要的。因此，在这个项目中，我们尝试了一种电量热法，它可以为我们提供关于电子转移或氧化还原反应的焓变的信息。这是我们第一次尝试测量电极反应产生的热量，我们设计并制作了新的测量电池。由于反应热由电子转移热和络合热组成，因此在反应阶段放出的热是相关物质浓度和电子转移量的复杂函数。因此，现阶段对实测热量的分析并不成功。我们将继续这个项目，并建立分析方法，以提取电子转移的有用信息。

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.