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现行高中化学教材中,有关蔗糖、淀粉的水解实验成功率很低。教材中是将银氨溶液加入已水解的蔗糖、淀粉溶液中,当加入银氨溶液后,试管中的溶液立即呈黑色,经加热后很难出现光亮的银镜。笔者经试验后作如下改进,成功率极高,可达100%,具体操作如下: 1.将蔗糖、淀粉分别用硫酸加热水解。2.用浓度较大的氢氧化钠溶液中和至溶液呈黄色,
In current high school chemistry textbooks, the success rate of sucrose and starch hydrolysis experiments is very low. In the teaching materials, silver ammonia solution is added to the hydrolyzed sucrose and starch solution. When the silver ammonia solution is added, the solution in the test tube immediately appears black, and it is difficult to appear a bright silver mirror after heating. The author made the following improvements after the test, the success rate is very high, up to 100%, the specific operation is as follows: 1. Sucrose, starch were heated by sulfuric acid hydrolysis. 2. Neutralize to a yellow solution with a large concentration of sodium hydroxide solution,