Complexation—Precipitation Interaction Formation of Insoluble Oxides and Hydroxides

3 Complexation—Precipitation Interaction Formation of Insoluble Oxides and Hydroxides 

The complex s formation may be inhibited by a precipitation phenomenon, or, in other words, a complex may be destroyed by a precipitation phenomenon. For example, the diamminesilver(I) complex is destroyed in certain conditions of concentrations by the addition of chloride ions. The precipitate of silver chloride is 

Inversely, a precipitate of silver chloride may be dissolved by adding ammonia. 

In this section, we are interested in the particular case of the interaction of the precipitation of insoluble metal oxides and hydroxides whose metallic ions also form complexes. Within this case, a frequent phenomenon exists the dissolution of an insoluble hydroxide or oxide after adding an excess of precipitating ions. This case is also investigated here. (We shall investigate the treatment of the complexation-precipitation interaction more deeply in Part V of this book.) 

It is an experimental fact that metallic hydroxides in usual experimental conditions spontaneously give insoluble oxides. Hence, mercuric ions give rise to the following equilibria  

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