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高中化学第一册(甲种本)85页(实验4—5)比较碳酸钠、碳酸氢钠和盐酸反应速度快慢,由于教材中没有规定盐酸浓度大小,常常因为盐酸浓度选择不当,使二者反应速度看不出差别,而且按课本规定的用试管做,可见度差。现将实验改进如下: 取两个规格一样的培养皿,放在幻灯投影器的载片台上,向培养皿中分别倒入1:40的稀盐酸至2/3处。然后同时加入等摩尔的Na_2CO_3粉末(2.1克),NaHCO_3粉末(1.7克)进行投影,在屏幕上可明显看到NaH CO_3比Na_2CO_3与盐酸反应剧烈。该实验成败的关键是盐酸的浓度,若盐酸的浓度(?)大,两个反应都非常激烈,便无法比较了。
High School Chemistry Vol.1 (Type A) page 85 (Experiment 4-5) compares the reaction rate of sodium carbonate, sodium bicarbonate, and hydrochloric acid. Because the textbook does not specify the concentration of hydrochloric acid, it is often because the concentration of hydrochloric acid is not properly selected. The difference in reaction speed does not show any difference, and the use of test tubes as specified in the textbooks has poor visibility. The experiment is modified as follows: Take two dishes of the same size, place them on the slide table of the slide projector, and pour 1:40 dilute hydrochloric acid into the culture dish to 2/3. Then, equimolar Na 2 CO 3 powder (2.1 g) and NaHCO 3 powder (1.7 g) were projected at the same time, and the reaction of NaH CO 3 with Na 2 CO 3 and hydrochloric acid was noticeable on the screen. The key to the success of the experiment is the concentration of hydrochloric acid. If the concentration of hydrochloric acid is large, the two reactions are very intense and they cannot be compared.