Dear Kritika, Yes, Ferrocyanide/Ferricyanide redox couple has a reversible electrode reaction. So if you apply a more positive potential than the E0' of the reaction, Fe2+ species are readily oxidized to Fe3+ and if you apply a less positive potential than the E0', Fe3+ species are readily reduced to Fe2+ on the surface of the electrode. This redox couple is a well-known example of a reversible electrode reaction in electrochemistry. I have

attached the cyclic voltamogram of this couple so you can observe how it behaves.

Besides, the following question has thoroughly answered this matter as well.

https://www.researchgate.net/post/Potassium_ferricyanide_or_potassium_ferrocyanide_for_cyclic_voltammetry

Good luck,

But why are we taking ferricyanide in a larger amount? Also, if we are doing chronoamperometry with this couple then we will apply only one potential (mainly oxidation potential), so ferrocyanide should be taken more but in papers, I have found ferricyanide is being taken in a larger amount.

It's not about the availability of ferricyanide being more than ferrocyanide because of its solubility. The amount of ferricyanide was taken about 460ng/cm^2 and ferrocyanide merely 8ng/cm^2 before the reaction even started. What is the reason behind this unequal amount?

Dear Kirita, please take a look on these papers:

1.- Eaton, W. A.; George, P.; Hanania, G. I. Thermodynamic Aspects of the Potassium Hexacyanoferrate(III)-(II) System. I. Ion Association. J. Phys. Chem. 1967, 71 (7), 2016–2021. https://doi.org/10.1021/j100866a007.

2.- Hanania, G. I.; Irvine, D. H.; Eaton, W. A.; George, P. Thermodynamic Aspects of the Potassium Hexacyanoferrate(III)-(II) System. II. Reduction Potential. J. Phys. Chem. 1967, 71 (7), 2022–2030. https://doi.org/10.1021/j100866a008.

Here is a clear explanation about your question 😉

Kind regards

Dear @erika, do you have these files?

Thanks

Hi Felipe Felipe Silva Semaan ! Glad to read you! Yes I have them

Let me add them ;)

Thank you very much @erika

With best regards

Thank you Erica :)))

i have a question about ferri/ferro.. is this solution stable as a stock? our EIS measurements have never appeared to have problems.. but perhaps EIS signals are different depending on how old the solution is?