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用单分子膜法测定阿佛加德罗常数,所用仪器简单,操作方便,适合中学生实验。但它只是一种粗略的方法,更精确的测定可采用电解法等其他方法。 本法是采用稀的硬脂酸的苯溶液铺展在水面上,使硬脂酸在水面上形成单分子膜来测定的。为什么硬脂酸能在水面上形成单分子膜?为什么要用硬脂酸的苯溶液?苯起什么作用?要解决这些问题,必须了解硬脂酸的分子结构特征和液体铺展等有关问题。
The Avogadro’s constant is determined by the monomolecular membrane method. The instrument used is simple and easy to operate. It is suitable for middle school students’ experiments. However, it is only a crude method, and more accurate measurements can be made by other methods such as electrolysis. The method is based on the use of a dilute solution of stearic acid in benzene to spread over the surface of the water and stearic acid to form a monomolecular film on the surface of the water. Why does stearic acid form a monomolecular film on the surface of water? Why do we use a benzene solution of stearic acid? What is the role of benzene? To solve these problems, we must understand the molecular structure characteristics of stearic acid and liquid spreading and other related issues.