デュマ法によるマイクロスケールモル質量測定実験における浮力の影響 [in Japanese] The effect of buoyancy on Dumas' molar mass measurement using microscale chemistry experiment [in Japanese]
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Dumas' molar mass measurement using a microscale experiment is useful for high school and university practical lessons. Firstly, a liquid sample is heated to a gaseous one in a container, and the generated gas is regarded as the ideal one. Secondly, it is cooled to a gas-liquid mixture, and its mass is measured. The molar mass is determined from the mass of a sample, the atmospheric pressure, the volume of a container, the temperature of boiling water. It is noticed that the buoyancy of the liquid component is negligible, but that of the gaseous one is not. Therefore, the buoyancy correction is inevitable in order to obtain the precise molar mass. Although the quanitative consideration for the buoyancy effects on neasured molar masses is of great importance in practical lessons, it has been hardly carried out. In this paper, the seven organic liquids such as cyclohexane, hexane, methanol, ethanol,2-propanol acetone, and ethyl acetate, which are all popular with high school and university chemistry classes, are chosen as samples, and the relation between their molar masses and the buoyancies generated by sample hases is theoretically investigated. From the viewpoints of microscale experiments, cyclohexane, hexane, and ethyl acetate are more suitable as molar mass measurement samples for university practical lessons.
- Kobe College studies
Kobe College studies 56(2), 109-117, 2010-01