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在教学中,为了使学生能熟练地掌握有关溶解度和析晶的计算,采用列表填数据(或代数式)的分析方法进行教学尝试,由于方法简便,思路清楚,适用范围广,学生容易掌握。例1 60℃时246克KNO_3溶液中含有96克KNO_3,把该溶液降至20℃时,有多少克KNO_3晶体析出?(KNO_320℃时的溶解度为31.6克) 解:设降温后析出X克硝酸钾列表:(单位克)列比例式:(96-X)/(31.6)=(246-96)/100解得X=48.6(克,填表时先填第一行原溶液的三个空格,再利用第一行的三个数据和题意填第二行。根据温度变化后的溶解度填第三行,由二、三行中选出简便易计算的
In teaching, in order to enable students to proficiently understand the calculation of solubility and crystallization, the use of a list of data (or algebraic) analysis method of teaching attempts, due to the method is simple, clear thinking, wide range of applications, students easy to grasp. Example 1 When 246 g of KNO 3 solution at 60 ° C contains 96 g of KNO 3, how many grams of KNO 3 crystal is precipitated when the solution is lowered to 20 ° C (31.6 g of KNO 3 at 320 ° C). Solution: After cooling, X g of nitric acid (96-X) / (31.6) = (246-96) / 100 Solution X = 48.6 (g, fill in the first line of the first line to fill the original three spaces , And then use the first line of the three data and fill in the second line of questions.According to the solubility of the temperature change fill the third line by two or three lines selected simple and easy to calculate