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纵观2001年各省区初中化学竞赛试题,不难看出计算题大多源于教材而高于教材,题目灵活有技巧,能考查出学生的思维素质.这些计算题可分为下列六大类:概念型计算、据式型计算、过程型计算、讨论型计算、综合型计算、应用型计算.1 概念型计算这类试题以含计算因素的概念为核心,考查学生对概念的理解层次及计算技能.初中化学含计算因素的概念主要有式量、元素的质量分数、溶解度、溶液的质量分数等.例1 将5.6g生石灰投入201.8g水中,所得溶液的温度为33℃,求该温度下该
Looking at the 2001 junior high school chemistry contest questions in various provinces and districts, it is not difficult to see that most of the calculation problems originate from the teaching materials and are higher than the teaching materials. The topics are flexible and skillful, and can identify students’ thinking qualities. These calculation problems can be divided into the following six categories: Concepts Type calculations, data type calculations, process type calculations, discussion type calculations, comprehensive calculations, and applied calculations. 1 Conceptual calculations This type of test involves the concept of computational factors as its core, examining students’ understanding of concepts and their calculation skills. The concept of calculating factors in junior high school chemistry includes formula, elemental mass fraction, solubility, mass fraction of solution, etc. Example 1 5.6 g of quick lime is put into 201.8 g of water, and the temperature of the resulting solution is 33°C.