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銀量法在化学分析上尤其在工矿或药品分析上,应用得非常广泛。但由于各种方法的条件不同,应用时往往引起誤差,因此有必要把有关的方法加以比較与說明,以供有关方面的参考。銀量法可以测定Cl~-、Br~-、I~-、Ag~+、CN~-、CNS~-等离子。在下文中皆以生成氯化銀反应为代表作比較详细的介紹。基准物的选擇与精制1.硝酸银:保証純淨的金屬銀是容易得到的,但是它不适用于直接制备硝酸銀标准液,因为它必須溶解于硝酸中,而过量的硝酸在多数情况下应当除去,只在Volhard法中才允許硝酸存在。所以应当用A.R.的硝酸銀来直接制备硝酸銀标准液。如果没有A.R.的硝酸銀,可以將不純的加以精制。精制的方法是在硝酸中重結晶一次,过濾,收集結晶,洗滌,在110°干燥,再在220°—250°烘15分钟(熔点208°),时間不应
The silver quantity method is widely used in chemical analysis, especially in the analysis of industrial and mineral or pharmaceuticals. However, due to the different conditions of various methods, errors are often caused when applied, so it is necessary to compare and explain the relevant methods for reference by relevant parties. Ag method can determine Cl~-, Br~-, I~-, Ag~+, CN~-, CNS~-plasma. In the following, a detailed introduction will be made on behalf of the silver chloride generation reaction. Standard selection and refining 1. Silver nitrate: It is easy to obtain pure metallic silver, but it is not suitable for the direct preparation of silver nitrate standard, because it must be dissolved in nitric acid, and excess nitric acid should in most cases In addition, only the presence of nitric acid was allowed in the Volhard method. Therefore, the silver nitrate standard solution should be prepared directly from A.R. silver nitrate. If there is no A.R. silver nitrate, the impure can be refined. The refining method is to recrystallize once in nitric acid, filter, collect the crystals, wash, dry at 110°, then bake at 220°-250° for 15 minutes (melting point 208°). The time should not be