How Is the Redox Equivalence Point Defined and Calculated in Complex Reactions?

[Big-Daddy]

I had a look at an online page for redox titrations (http://www.titrations.info/potentiometric-titration-equivalence-point-calculation). I can extend my understanding of that page far enough to say that for two half-reactions v_A A + v_e1 e^- ⇔ v_B B (v_Species is the stoichiometric coefficient) and v_C C + v_e2 e^- ⇔ v_D D, the point at which [A] = v_A/v_D * [D] and [ B] = v_B/v_C * [C] is the equivalence point.

However, what is the definition of the redox equivalence point if we instead have the following reactions occurring:
v_A A + v_B B +...+ v_e1 e^- ⇔ v_C C + v_D D and v_E E + v_F F +...+ v_e2 e^- ⇔ v_G G + v_H H

And how, in these cases, can we calculate the potential at the equivalence point? (The linked web-page only goes through a more basic case.)

 

[Zefram]

Hello there,

Thank you for sharing your understanding of redox titrations and the link to the titrations.info website. I can provide some additional information and clarification on the topic of redox equivalence points.

Firstly, the definition of a redox equivalence point is the point in a titration where the moles of the oxidizing agent (species being reduced) are equal to the moles of the reducing agent (species being oxidized). This means that all of the reducing agent has been completely consumed by the oxidizing agent, resulting in a balanced redox reaction.

In the case of multiple reactions occurring, as you have mentioned, the concept of equivalence point remains the same. However, the calculation of the equivalence point potential becomes more complex. This is because the potential at the equivalence point depends on the individual potentials of each half-reaction involved in the redox reaction. These potentials can be calculated using the Nernst equation, which takes into account the concentrations and activities of the species involved.

To calculate the potential at the equivalence point, you would need to know the individual potentials of each half-reaction and the concentrations of all species involved. This can be quite challenging and may require advanced knowledge of electrochemistry and thermodynamics.

I hope this helps to answer your question. If you have any further inquiries, please don't hesitate to ask. Thank you for your interest in redox titrations and their applications.