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在强酸弱碱滴定中,出现一种“奇怪”的现象。用HCl滴定Na_2CO_3时(酚酞作指示剂)无气泡产生;若用Na_2CO_3滴定HCl时(指示剂同前),产生大量气泡。为什么两种相同的物质参加反应,出现这种“奇怪”的现象,其反应生成物是否相同呢?对此问题谈谈我的一点看法。用HCl滴定Na_2CO_3为什么无气泡产生,生成的产物是什么?我们知道,Na_2CO_3是二元弱碱,它在溶液中产生二级水解。
In the titration of strong acid and weak alkalis, a “strange” phenomenon occurs. When titration of Na 2 CO 3 with HCl (phenolphthalein as an indicator) no bubbles were generated; if HCl was titrated with Na 2 CO 3 (indicator same as before), a large amount of bubbles were generated. Why do two kinds of the same substances participate in the reaction and this kind of “strange” phenomenon occurs? Is the reaction product the same? Let me talk a little bit about this point of view. Why is no bubble generated when titrating Na_2CO_3 with HCl and what is the product? We know that Na_2CO_3 is a dibasic weak base which produces secondary hydrolysis in solution.