General Considerations on Internal Redox Indicators

At the equivalence point of a satisfactory redox titration, there is a sharp change in 

The only means of detection studied in this chapter is the use of the internal redox 

The internal redox indicators are dissolved in the titrand solution. They are organic dyes whose oxidized and reduced forms are different colors. They are derivatives for which their oxidation-reduction is achieved rapidly. Their half-redox equilibrium may be symbolized by 

They are added in a very weak concentration in order not to change the redox potential of the solution, since they are redox couples themselves. 

Nernst s equation concerning them gives the following relation  

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