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在化学教学中,学生曾问过我这样一道填空题:“75％的酒精溶液中,溶剂是______。”我认为这道填空题,按照课本上所论述的规定原则,是无法作出正确答案的。 中学课本中的“溶液”,是从分散系的角度下的定义,按照这个定义,溶液可以是气态溶液、液态溶液和固态溶液。液态溶液是常见和用途最广泛的一种分散系,其中以水为溶剂的溶液尤为重要。通常我们听说的溶液,如无特别说明的,指的都是水溶液。在液态溶液中,就溶质来说,它可以是气态、液态和固态物质。而以液态物质作溶质时,亦即两种液态物质互相溶解时,究竟应以哪种物质作溶质,哪种物质作溶剂,课本举例说:酒精和水相互溶解时,当“少量的水溶解在酒精里,就可以把水作为溶质,酒精作为溶剂。”但当硫酸和水相互溶解时,从百分比浓度看,又是以量多的硫酸为溶质,以量少的水为溶剂。实际上,前者是以量多量少、后者是按溶液的本性规定了溶质、溶剂。后者符合通常习惯,也比较切合实际,像含酒精75％的消毒液,起消毒作用的是酒精而不是水,水只是介质,以酒精作溶质,体现了溶液的本性,符合通常习惯,也
In chemistry teaching, the students once asked me to fill in the blanks: “In the 75% alcohol solution, the solvent is ______.” I think this fill-in question cannot be answered correctly according to the principles stated in the textbook. of. The “solution” in the middle school textbook is defined from the perspective of a dispersion system. According to this definition, the solution can be a gaseous solution, a liquid solution, and a solid solution. Liquid solutions are the most common and widely used dispersions, with water-based solutions being particularly important. The solutions we usually hear, if not specified, refer to aqueous solutions. In a liquid solution, in terms of solute, it can be gaseous, liquid, and solid material. When a liquid substance is used as a solute, that is, when two liquid substances are dissolved in each other, which substance should be used as a solute and which substance is used as a solvent, textbooks for example: When alcohol and water dissolve each other, when “a small amount of water dissolves In alcohol, water can be used as a solute and alcohol as a solvent.” However, when the sulfuric acid and water dissolve each other, the percentage concentration of sulfuric acid is used as the solute, and less water is used as the solvent. In fact, the former dictates the amount of solute and solvent in a large amount, and the latter dictates the nature of the solution. The latter is in accordance with the usual habits and is more practical. Like disinfectant containing 75% alcohol, alcohol is used instead of water for disinfection. Water is the medium, and alcohol is used as the solute, which reflects the nature of the solution and conforms to the usual habits.