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物质百分率的计算是化学中常用的一种题型,生产和生活实践中也常用到。如何理解和解答这方面的习题呢?笔者通过多年的教学,将百分率的计算归纳为如下几种类型,仅供同行和学生参考。一、求物质的纯度这种题目可用通式“某物质的纯度=(该纯净物的质量/物质的总质量)×100%”来求解,有时题目不同,也有不同的解法。例:某尿素样品中含氮量为40%,试求样品尿素的纯度。解:(1)设该尿素样品重100克,则其中含氮元素的质量有40克。
The calculation of the percentage of matter is a commonly used type of question in chemistry, which is also commonly used in production and life practice. How to understand and answer the exercises in this area? Through years of teaching, the author has summarized the percentage calculations into the following types, which are for reference only by peers and students. First, the purity of the substance can be used to solve this problem can be used in the general formula “the purity of a material = (the quality of the pure material / total mass of the material) × 100% ” to solve, sometimes the title is different, there are different solutions. Example: The nitrogen content of a urea sample is 40%, and the purity of the sample urea should be determined. Solution: (1) Assuming that the urea sample weighs 100 grams, the mass of the nitrogen-containing element is 40 grams.