论文部分内容阅读
“比例型”试题点多面广、迁移性较强。现以部分典型试题为例,浅谈解题的方法和技巧,仅供参考。1 守恒法 例1 经实验测得某一中性溶液由Mg~(2+)、Al~(3+)、Cl~-、SO_4~(2-)四种离子构成,其中Mg~(2+)、Al~(3+)、SO_4~(2-)的离子个数比为3:3:1.则可推断该溶液中Al~(3+)、SO_4~(2-)、Cl~-离子的总电荷数之比是__。 解析:当SO_4~(2-)为n个时,Mg~(2+)、Al~(3+)的离子数目均应是3n个。溶液中阳离子所带正电荷总数为:2×3n+3×3n=15n。根据电荷守恒原理,溶液中所有阴离子所带负电荷总数亦应为15n。则其中Cl~-所带负电荷总数
The “proportional” test questions have many aspects and are highly mobile. Now take some typical questions as an example, the methods and techniques for solving problems are for reference only. 1 Conservation Law 1 A neutral solution was measured by experiments. It was composed of four ions, Mg~(2+), Al~(3+), Cl~-, and SO~4~(2-), of which Mg~(2+). The ratio of Al 3+ and SO 4 2- ions is 3:3:1. It can be inferred that Al 3+, SO 4 2-, Cl − ions in the solution. The ratio of the total charge is __. Analysis: When SO_4~(2-) is n, the number of ions of Mg~(2+) and Al~(3+) should be 3n. The total positive charge carried by the cations in the solution is: 2×3n+3×3n=15n. According to the charge conservation principle, the total number of negative charges carried by all anions in the solution should also be 15n. The total number of negative charges charged by Cl~-