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我系一直使用华中师院等校编写的《分析化学》教材,该教材对硫化氢系统中铜组阳离子的系统分析采用甘油-碱法.通过历届学生的实验证实,甘油-碱法对铜组阳离子的系统分析,效果欠佳.主要问题是:用甘油-碱法不能使Cd~(2+)沉淀完全,当Cd~(2+)的浓度较小时,就根本不产生Cd(OH)_2沉淀.即使加大练习液中Cd~(2+)的浓度(原用100mg/ml,陕西师范大学用20mg/ml),沉淀量也较少,而且夹杂有铋、铜的共沉淀,下一步鉴定Cd~(2+)时形成灰黑色的沉淀,难以证实Cd~(2+)的存在.为此我们设计了这个新方案(见图表).
I have been using the Central China Normal University and other schools to prepare the “Analytical Chemistry” teaching materials, the text of the hydrogen sulfide system in the system of copper cations using glycerol - alkali method. Through the experiments of previous students confirmed that glycerol - alkali method of copper group The main problem is that the Cd 2+ can not be completely precipitated by glycerol-alkali method, and Cd (OH) 2 does not produce at all when the concentration of Cd 2+ is small Even if the concentration of Cd2 + in the exercise solution is increased (originally 100mg / ml, Shaanxi Normal University with 20mg / ml), the amount of precipitation is less, and the mixture of bismuth and copper coprecipitation, the next step Identification of Cd ~ (2+) formed a gray-black precipitate, it is difficult to confirm the existence of Cd ~ (2+), for which we have designed this new scheme (see chart).