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中学化学计算技能被作为“双基”的重要内容写在教学大纲中。据统计每年化学高考试卷中涉及计算问题的分值高达35--40分。考生的失误常因计算技能的功底不足,数学知识的迁移失之把握。为此笔者特将零散出现在中学化学教材及高考化学试卷中的数学知识技能揽聚如下,以飨读者。 一、比和比例 比和比例是化学中重要的知识点,是基本的计算技能之一,也是构成许多化学概念的基础。 1.百分比。百分比渗入化学知识中甚为普遍,例如求化肥中有效成份含量的百分比、有机物含碳百分比、计算气体体积百分比、电离度、溶液的百分比浓度、转化率以及化工生产中原料配比的分配等都用列百分比的数学计算。现仅举一例以说明之。 例1 MCE93—19在1升浓度为C摩/升的弱酸HA溶液中HA、H~+和A~-的物质的量之和为nC摩,则
Secondary school chemistry calculation skills are included in the syllabus as an important part of the “dual base”. According to statistics, the scores involved in calculation questions in the annual chemistry high test papers are as high as 35--40 points. Candidates’ mistakes are often due to lack of skills in calculation skills and the loss of knowledge in mathematics. For this reason, the author has specially scattered the mathematics knowledge and skills that appear in middle school chemistry textbooks and college entrance examination chemistry papers to gather together as follows. 1. Ratio and Ratio Ratios and ratios are important knowledge points in chemistry. They are one of the basic computational skills and form the basis of many chemical concepts. 1. Percentage. Percentage infiltration of chemical knowledge is very common, for example, to determine the percentage of active ingredient content in chemical fertilizers, the percentage of carbon in organic matter, the percentage of calculated gas volume, the degree of ionization, the percentage concentration of solution, the conversion rate, and the allocation of raw materials in chemical production. Use the mathematical calculation of the column percentage. Just to give an example to illustrate. Example 1 In the case of MCE 93-19, the sum of the amounts of HA, H~+ and A~- in the 1 liter of weak acid HA solution with a concentration of Cm/l is nC.