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传统的络合滴定终点的确定方法是指示剂法,其准确度和敏锐度与体系的log K’_(MY)C_M及P_M-P_(Meo)的大小有关,当logK’_(MY)C_M较小时,等当点突跃较小,指示剂变色不敏锐,易产生较大误差。即使体系logK’_(MY)C_M较大,终点指示剂变色敏锐,但在临近等当点时,滴定需格外注意,稍有疏忽,就会造成人为误差。线性法在络合滴定中的应用,可以克服上述不足。该方法的操作和结果计算与线性法在氧化还原滴定中的应用基本相同.具有操作简便,重现性好的特点。一基本原理设有V_0mlC~0M金属离子,用VmlC_Y~0M EDTA进行滴定。根据物料平衡、络合平衡、当量平衡可得下面式子:
The traditional method of determining the end point of complexometric titration is the indicator method. Its accuracy and acuity are related to the log K ’_ (MY) C_M and P_M_P_ (Meo) of the system. When log K’ _ (MY) When smaller, the equivalent point jump smaller, the indicator is not sensitive to discoloration, easy to produce greater error. Even if the system logK ’_ (MY) C_M larger, the endpoint indicator discoloration sharp, but near the equivalence point, the titration should pay special attention to a little negligence, it will cause human error. Linear method in the complexation titration can overcome the above deficiencies. The operation of the method and the calculation of the results are basically the same as that of the linear method in the redox titration, which has the advantages of simple operation and good reproducibility. A basic principle with V_0mlC ~ 0M metal ions, with VmlC_Y ~ 0M EDTA titration. According to the material balance, complex balance, equivalent balance available the following formula: