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1.在沒食子酸稀溶液中加入Fe~(+++)观察到溶液的顏色随pH值的改变而变化;在pH=7.0以下,溶液呈現紫色。測定了在pH2-7,波長400-650mμ范圍內的光吸收曲綫,指出有一种络合物形成,其最大吸收在550mμ,克分子消光系数为4.13×10~3。研究了溶液的pH值对絡合物形成的影响,指出pH在5.0-7.0絡合物达到稳定。 2.用連續变化法和克分子比法測定了溶液中络合物的組成,得到沒食子酸:铁=1:1。测得絡合物的稳定常数为3.96×10~5。电迁移实驗証明络合物在溶液中是携带正电荷。志謝:本工作是在蔡镏生教授亲切指导下进行的,特此表示衷心感謝。
1. The addition of Fe ~ (+++) in dilute gallic acid solution changes the color of the solution as the pH changes; at pH = 7.0, the solution appears purple. The light absorption curve was measured at a wavelength range of 400-650 mμ at pH 2-7, indicating a complex formation with a maximum absorption of 550 mμ and a molar extinction coefficient of 4.13 × 10 -3. The effect of the solution pH on the complex formation was investigated, indicating that the complex was stable at pH 5.0-7.0. 2. The composition of the complex in the solution was determined by the continuous variation method and the molar ratio method, and gallic acid: iron = 1: 1 was obtained. The stability constant of the complex was 3.96 × 10 ~ 5. Electromigration experiments show that the complex is carrying a positive charge in solution. Thank you: This work is carried out under the guidance of Professor Cai Yusheng, hereby expresses my heartfelt thanks.