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讨论离子共存问题即离子之间能否反应的题目,在高考中的重现率、失分率都相当高。因为这部分知识综合性强,能力要求高,有较好的区分度、效度、信度。这一知识点的题型主要有选择题和填空题,为了能更好地掌握这部分知识,现从以下几个方面去考虑:一、知识方面1.离子之间发生复分解反应,即产生沉淀、气体(易挥发性物质)、难电离物质时不能大量共存。①沉淀:a.酸:常见的有 H_2SiO_3;b.碱:常见的有Mg(OH)_2、Al(OH)_3、Cu(OH)_2、Fe(OH)_3;c.盐:常见的有 CaCO_3、BaSO_4、AgCl、CuS 等。
Discussion of the ion coexistence problem is the question of whether or not the ions can react to each other. The recurrence rate and the loss rate in the college entrance examination are quite high. Because this part of the knowledge is comprehensive and highly demanding, it has better differentiation, validity, and reliability. There are multiple choice and fill-in questions for this knowledge item. In order to better grasp this part of the knowledge, we now consider from the following aspects: First, the knowledge aspect 1. The metathesis reaction occurs between ions, that is, precipitation occurs. , gas (volatile substances), and difficult ionized substances cannot coexist in large amounts. 1 precipitation: a. acid: common H_2SiO_3; b. alkali: common Mg (OH) _2, Al (OH) _3, Cu (OH) _2, Fe (OH) _3; c. salt: common CaCO_3, BaSO_4, AgCl, CuS, etc.