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本实验是定量实验,虽然操作比较简单,但精确度要求较高,组织不好,误差很大。我们的做法是: 一、实验课前,要求学生清楚了解本实验的操作要求。向学生讲明本实验关键在称量、控温、溶解、蒸发四个基本环节。要求大家细心操作,尽量避免误差。并分配好那些小组测某一温度的溶解度。二、称量是本实验成功的关键之一。由于目前学校使用的托盘天平精确度不高,学生称量时不注意,往往造成较大误差。建议:(1)实验前教师应亲自校正每架天平;(2)要求学生称量时天平一定要放平;(3)蒸发皿应预置干燥器中干燥后由学生领用。三、控制所需饱和溶液的温度是本实验的又一
This experiment is a quantitative experiment, although the operation is relatively simple, but the accuracy of the higher, poor organization, great error. Our approach is: First, before the experiment class, require students to clearly understand the operational requirements of the experiment. Explain to students that the key to the experiment in the weighing, temperature control, dissolution, evaporation of the four basic areas. Ask everyone to operate carefully, try to avoid errors. And assigned those groups to measure the solubility of a certain temperature. Second, weighing is one of the keys to the success of this experiment. Due to the current school pallet balance accuracy is not high, students do not pay attention to weighing, often resulting in greater error. Suggestions: (1) Before the experiment, the teacher should personally calibrate each balance; (2) The balance must be leveled when the student is required to weigh; (3) The evaporating dish should be preset for use by the student after drying in the drier. Third, control the temperature of the saturated solution is another of the experiment