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离子方程式的书写或正误判断是高考的热点.学生往往因为各种原因不能正确判断出现错误而失分.本文就近年高考中该类试题出现的错误进行分析与归纳.一、是否符合反应客观性原则例1能正确表示下列反应的离子方程式是().A.浓盐酸与铁屑反应:2Fe+6H+=2Fe3++3H2↑B.钠与CuSO4溶液反应:2Na+Cu2+=Cu↓+2Na+C.NaHCO3溶液与稀H2SO4反应:CO32-+2H+=H2O+CO2↑D.向FeCl3溶液中加入Mg(OH)2:3Mg(OH)2+2Fe3+=2Fe(OH)3+3Mg2+分析:A项,不符合客观性原则,Fe与稀HCl、H2SO4反应生成的是Fe2+,不是Fe3+;B项,Na投入水中与水反应生
Writing or correcting the ion equation is a hot spot for college entrance examination. Students often fail to score correctly because of various reasons. This article analyzes and summarizes the mistakes that have occurred in recent college entrance examinations. Principle Example 1 Correctly shows that the ion equation for the following reaction is (). A. Concentrated hydrochloric acid and iron filings reaction: 2Fe+6H+=2Fe3++3H2↑ B. Sodium reacts with CuSO4 solution: 2Na+Cu2+=Cu↓+2Na+ C. Reaction of NaHCO3 solution with dilute H2SO4: CO32-+2H+=H2O+CO2↑ D. Add Mg(OH)2:3Mg(OH)2+2Fe3+=2Fe(OH)3+3Mg2+ to FeCl3 solution Analysis: Item A , does not meet the principle of objectivity, Fe reacts with dilute HCl, H2SO4 to produce Fe2+, not Fe3+; item B, Na reacts with water in the input water