Further Considerations Concerning Symmetrical Titrations Titration Error

2 Further Considerations Concerning Symmetrical Titrations Titration Error 

The preceding results are valid for all symmetric titrations ( i = 2. with, in particular, i = ti2 1). The general (and rigorous) equation of the curve describing the titration corresponding to reaction (17.2) is 

When the difference AF° is sufficient (A ° 0.24 V), the curve portions before and after the equivalence point can be, as already seen, described by the relations 

it is convenient to make clear the conditions in which the general Eqs. (17.13) and (17.14) can be reduced to the simplified ones (17.15) and (17.16), that is, to make clear the conditions in which the exponentials ei and C2 are successively negligible with respect to unity in Eqs. (17.13) and (17.14). It is obvious that the exponential numerical values depend on the difference of the formal potentials 

A ° = E° 2 on the values E° 2 and E° themselves, and also on the fraction titrated q , which plays a part in the E value through Eqs. (17.13) and (17.14). A calculation shows that when A ° 0.24 V, the exponential Ca (relative to the titrant) is perfectly negligible with respect to unity, as long as the fraction titrated is very close to unity and under it that is, 

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