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在化学计算题中,常遇到有关讨论取值范围的计算题,此类题目难度较大。学生在讨论取值范围过程中易丢三落四,将取值范围搞错,造成错解。我在讲课中利用了“数轴”这一直观教具,既提高了学生的解题速度,又提高了学生解题的准确性。 例题,等量的钠、镁、铝与等量的盐酸作用产生H_2量,可出现下列四种情况:①Na>Mg=Al;②Na=Mg=Al;③Mg=Al>Na;④Al>Mg>Na。若盐酸中所含氯化氢均为1摩时,将满足上述四种情况所需金属的量x,填入下表
In chemical calculation questions, the calculation questions that discuss the value range are often encountered. Such questions are more difficult. In the process of discussing the range of values, students are prone to losing their seats, mistaking the range of values, and causing mistakes. In my lecture, I took advantage of the visual aids “number axis”, which not only improved students’ problem solving speed, but also improved the accuracy of students’ problem solving. For example, the same amount of sodium, magnesium, aluminum and the same amount of hydrochloric acid produce H2 amount, the following four conditions can occur: 1Na> Mg = Al; 2Na = Mg = Al; 3Mg = Al> Na; 4Al> Mg> Na . If hydrochloric acid contains 1 mol of hydrogen chloride, fill the following table with the amount of metal x that satisfies the above four conditions.