# What is the equivalence point in the context of a redox titration? [closed]

We know the standard reduction potential of the species: $$\ce{Fe^{3+}}/\ce{Fe^{2+}}$$, $$\varepsilon_1$$ and the standard reduction potential of the species: $$\ce{MnO_4}^{-}/\ce{Mn^{2+}}$$, $$\varepsilon_2$$. If we know the concentration of the ferrous cation in the initial solution $$c_0$$ in sulphuric medium $$c_s$$, at equivalence point in titration with potassium permanganate $$c_t$$ how to determine the ratio of concentrations of ferric and ferrous cations?

What I have thought on the subject is that Nernst's potential equation is useful, but I don't really know what equivalence point should mean in a redox context. I know it only from elementary acid-base equilibria.

$$\ce{5 Fe^2+(aq) + MnO4-(aq) + 8 H+(aq) -> 5 Fe^3+(aq) + Mn^2+(aq) + 4 H2O(l)}$$
the point of equivalence is when the initial molar amount of $$\ce{MnO4-(aq)}$$ is equal to 1/5 of the initial molar amount of $$\ce{Fe^2+(aq)}$$.
$$E = E^{\circ}_{\ce{MnO4-}/\ce{Mn^2+}} + \frac{RT}{5F} \ln{\left(\frac{[\ce{MnO4-}][\ce{H+}]^8}{[\ce{Mn^2+}]}\right)}=E^{\circ}_{\ce{Fe^3+}/\ce{Fe^2+}} + \frac{RT}{F} \ln{\left(\frac{[\ce{Fe^3+}]}{[\ce{Fe^2+}]}\right)}$$