Redox Phenomena, Complexation, and Precipitation

the calculation of values (pH = 14) starting from values (pH = 0) is easily achieved by adding the free enthalpies of the processes whose resultant is equivalent to the transformation. Thus, fi° (Br03 /Br ) is calculated after the following two equilibria (their free enthalpy expressions are given in brackets)  

It s important to note that some of these examples concern redox couples where one of the members is under the form of a precipitate, which constitutes a pure phase. These are couples in which the following intervene  

The superimposition of precipitation and/or complexation equilibria to the redox equilibrium may lead to the phenomena described in Sect. 14.2.1, which are of analytical interest. 

1 The Stabittzation of a Redox Couple by Complexation or Precipitation of One of Its Members 

Another example is provided by the cuprous ion Cu+. It is not stable in aqueous solution no matter what its pH value is. However, it can be stabilized under the form of a precipitate. Then it can, for example, enter into a redox equilibrium with the cupric ion Cu + and with another ion. Thus, in the presence of iodide ions, we notice the formation of cuprous iodide, which precipitates. The precipitated copper (I) iodide may itself enter into a redox equilibrium. The evoked reactions are 

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