Abstract
Two electroanalytical instruments, such as a power supply for electrogravimetry and a constant-current coulometric analyzer, were developed for quantitative semimicro analysis experiments in an undergraduate course. The power supply for electrogravimetry contained a variable-voltage power supply and an electronic load; they controlled the potential and current of electrolysis, respectively. It also contained an embedded controller and a liquid-crystal display (LCD), and could display the potential and current. It was applied to the determination of copper in copper(II) sulfate pentahydrate. The obtained results were 98∼103% of theoretical values. On the other hand, the coulometric analyzer contained a constant-current power supply for electrogeneration of the titrant, a constant-voltage power supply for the indicator circuit, an amplifier and an analog-to-digital converter for the indicator current measurement, and an embedded controller and an LCD to display the indicator current and the elapsed time of electrolysis. It was applied to the determination of thiosulfate with electrogenerated iodine. The obtained results were in good agreement with a conventional instrument. Both instruments were not only applicable to quantitative semimicro analysis experiments, but also their dimensions and power consumption were markedly reduced.
