(中南大學 冶金與環(huán)境學院，長沙 410083)
摘 要: 根據(jù)配位化學的熱力學平衡原理，繪制Co2+-H2O體系的羥基配合離子的濃度pc-pH圖、配離子分率αn-pH圖(lgαn-pH圖)和Co(OH)2的條件溶度積pPs-pH圖。pc-pH圖描述Co(OH)2(s)溶解平衡時鈷的總離子平衡濃度與pH值的關(guān)系。當pH值為10~13時，Co(OH)2(s)的溶解度最小；αn-pH圖指出各種羥基配離子分率與pH值的關(guān)系，在不同pH值條件下，鈷離子形成不同種類的羥基配離子；溶液中主要存在Co(OH)+、Co(OH)3-、Co(OH)42-、Co4(OH)44+這4種羥基配離子以及少量Co(OH)2和Co2(OH)3+。pPs-pH圖顯示了Co(OH)2(s)的條件溶度積與對應pH值之間的關(guān)系：當pH值為9~11時，Co(OH)2(s)的條件溶度積最小。
關(guān)鍵字: 配位化學；溶解平衡；羥基配離子分率；條件溶度積
（1. School of Metallurgy and Environment, Central South University, Changsha 410083, China）
Abstract:Based on the thermodynamic equilibrium principle of complex chemistry, the diagrams for the concentration of complex ions pc-pH, the ratio of Co2+ hydroxyl complex ions αn-pH, conditional solubility product of the hydrate to pH in the Co2+-H2O system were drawn, respectively. The relationship between the equilibrium concentration of total cobalt ions and pH value was shown in Co2+-H2O system, when the dissolution of Co(OH)2 is in equilibrium．The solubility of Co(OH)2 is the least at pH value of 10-13. The relationship of hydroxyl complex ions and pH value is shown in the diagram of αn-pH, the cobalt ions will turn into different hydroxyl complex ions according to different pH values. There are Co(OH)+, Co(OH)3-, Co(OH)42- and Co4(OH)44+ existing in the Co2+-H2O system, and a little of Co(OH)2 and Co2(OH)3+. The diagram for the conditional solubility product pPs-pH indicates that the pPs reaches the minimum value at pH value ranging from 9 to 11.
Key words: complex chemistry; solubility equilibrium; complex ions ratio; conditional solubility product
