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有的化学高考题出得巧,若用常规法解较难入手,耗时误事,这类题称得上特殊题。解这类题时一定要设法找出题中的巧,然后巧解,从而化难为易。 例1 (87。四、1)有A、B、C三种一元成碱,它们的分子量之比为3∶5∶7。如果把7摩A、5摩B和3摩C混和均匀,取混和碱5.36克,恰好能中和含0.15摩HCl的盐酸。试求A、B、C的分子量各是多少? 分析:题中巧在三种一元碱的混和物和一种一元酸反应,故三种一元碱的混和物中的总物质的量与盐酸的物质的量相等,故可用平均摩尔质量求解,既简单又巧妙。
Some chemical college entrance examination questions are clever, if using conventional methods to solve more difficult to start, time-consuming mistakes, such questions can be called special questions. When solving such questions, we must try to find out the cleverness in the questions and then work out the solutions so that it is difficult to understand. Example 1 (87. Four, 1) has three monobasic A, B and C bases, and their molecular weight ratio is 3:5:7. If 7 Ma, 5 Ma, and 3 Ma are blended homogeneously, 5.36 g of base is mixed to just neutralize hydrochloric acid containing 0.15 molar HCl. What are the molecular weights of A, B and C? Analysis: In the case of Qiao in the mixture of three monobasic bases and one monobasic acid reaction, the total amount of substances in the mixture of three monobasic bases and hydrochloric acid The amount of matter is equal, so it can be solved with the average molar mass, which is both simple and clever.