What is a quasi-reversible redox process?

Question

In cyclic voltammetry, a reversible process should have Ic/Ia = 1.
But when its not 1, sometimes it is described as quasi-reversible. When is the process considered reversible / quasi-reversible /Irreversible?

Answer 1

The word "reversible" is used in two different ways in cyclic voltammetry. Chemical reversability means that the product of the forward wave hangs around long enough for the reverse electrochemical reaction to occur on the return wave, so that, as you correctly say, ic/ia = 1

Electrochemical reversability means that the electrode process is fast compared with diffusion, so that the solution immediately next to the electrode is in thermodynamic equilibrium with the potential on the working electrode. The test for this is that the separation between forward and return wave is equal to that for a known electrochemically reversible reaction in the same cell, such as ferrocyanide/ferricyanide in aqueous solution or the oxidation of ferrocene in organic solvents. if your system is working correctly, this should also be close to what is predicted by theory, which if I remember rightly is around 59 mV at room temperature.

You need to check, because different people use terms in slightly different ways, but I would tend to say that the process is quasi-reversible if you can still see the return wave but with amplitude less than the forward wave.

Answer 2

Quasi Reversible Cyclic Voltammetry

Answer 3

In the case of the current global warming trend,yes. A naturalwarming might not be reversible, but remember, this one is caused by our technology--mainly our use of fossil fuels. By shifting to non-polluting systems of energy production, we can eliminate all or most of the CO2 emissions. Then, even if we can't devise means of removing the CO2 from the atmosphere, we'll at least keep it from getting worse--and the excess CO2 will break down eventually--though that will take decades. So--yes. Not quickly, but we can reverse the global warming.