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高中《化学》第三册第六单元第二节《性质实验方案的设计》一文中,关于草酸稳定性的实验方案的设计装置如图1所示。该装置图的错误有:(1)试管口微向下倾斜。笔者亲自做了实验,带有两个结晶水的草酸晶体的熔点为101℃,用酒精灯稍微加热,晶体即熔化成为液体向试管口流去,从而使实验无法进行,所以应改为试管口向上倾斜大约45°。(2)导管直接插入澄清的石灰水中以检验草酸分解产生的 CO_2。向澄清的石灰水中加入草酸溶液,石灰水很快变浑浊,那么用该装置证明 CO_2的存在,显然是不科学
The design of the experimental scheme for oxalic acid stability is shown in Figure 1 in the second section of the sixth section of the “Chemicals” Volume III of the High School. The errors in the device diagram are: (1) The mouth of the test tube is slightly inclined downward. The author personally experimented that the melting point of the oxalic acid crystals with two crystal waters is 101°C, and heating slightly with an alcohol lamp causes the crystals to melt and become liquid to flow out of the test tube, thus making the experiment impossible, so it should be changed to the test tube mouth. Tilt up about 45°. (2) The catheter is inserted directly into the clarified lime water to examine the CO2 produced by oxalic acid decomposition. After adding oxalic acid solution to the clarified lime water, lime water quickly becomes turbid. It is obviously unscientific to use this device to prove the existence of CO_2.