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电解质溶液比较型选择题,涉及电离度比较、加水稀释倍数比较、加水体积比较、浓度变化比较、酸碱性比较、中和反应时所耗酸、碱体积比较等。笔者例谈几种解题技巧。 一、巧设过程,联系比较 例1 等量的苛性钠溶液分别用pH值=2和pH值=3的醋酸溶液中和,设消耗醋酸溶液的体积依次为Va、Vb,则两者的关系正确的是( )。 A.V_a>10V_b B.V_b=10V_a C.V_b<10V_a D.V_b>10V_a 析:由题知V_a与V_b中所含醋酸分子总量相等(未电离前)。假设过程: 不难确定V_b>10V_a,故答案选D。 例2 根据下表数据(均在相同温度下测定):
Electrolyte solution comparative multiple-choice questions, involving the comparison of ionization degree, water dilution ratio comparison, water volume comparison, concentration change comparison, acid-base comparison, acidity and alkali volume comparison during neutralization reaction, etc. The author discusses several problem-solving techniques. First, the process of skillfully arranged, contact Comparative Example 1 The same amount of caustic soda solution was neutralized with acetic acid solution with pH=2 and pH=3, respectively, and the volume of acetic acid solution was assumed to be Va, Vb, then the relationship between the two. the correct one is( ). A.V_a>10V_b B.V_b=10V_a C.V_b<10V_a D.V_b>10V_a Analysis: It is known that the total amount of acetic acid molecules contained in V_a and V_b is equal (before ionization). Assumption process: It is not difficult to determine V_b>10V_a, so the answer is D. Example 2 According to the following table (all measured at the same temperature):