在沉淀反应中,所用沉淀剂与被沉淀离子生成络离子时,沉淀溶解度最小时游离沉淀剂浓度的计算方法已有叙述。但作为试验的理论指导来说,应计算出沉淀溶解度最小时沉淀剂的最适过量浓度。它是存在于溶液中游离的和络合的总的沉淀剂浓度。本文将叙述在下列情况下最适过量浓度的计算方法。 The method of calculating the concentration of the free precipitant when the precipitation solubility is minimized has been described in the precipitation reaction when the precipitating agent used and the ions to be precipitated form a complex ion. However, as a theoretical guide to the test, the optimum excess concentration of precipitant should be calculated when the solubility of precipitates is minimized. It is the total free and complexed precipitant concentration that is present in the solution. This article will describe the calculation of the optimum concentration in the following cases.