Question

Describe exactly what experiments you would do in cyclic voltammetry (CV), what data you would collect, and how to analyze the data to distinguish between a reversible and irreversible electrochemical reaction. Describe the features of the CV that you would measure and what the results mean; how would you decide if the reaction is reversible or irreversible?

Answer 1

Cyclic voltammetry: It ìs a most widely used technique for aquiring qualitative information about electrochemical reaction.

The Cyclic voltammetry(CV) is characterized by 4 parameters. They are:

1) Anodic current

2) Anodic potential

3) Cathodic potential and

4) Cathodic current

When we add a redox species (analyte) to the electrochemical cell containing working electrode, counter electrode, reference electrode in suitable electrolytic solution and these electrodes connected to the potentiometer. There are three types of electrochemical reaction that takes place. They are:

1. Reversible reaction

2. Irreversible reaction

3. Quasi reversible reaction

These type of reaction depend on rate at which electron transfer occur between working electrode and solution redox species.

If reaction is reversible then :

A) The rate of electron transfer between working electrode and solution redox species is fast.

B) It is further checked by analyzing CV graph, the difference between anodic potential and cathodic potential is equal to 59/n mV where n= number of electron involved in redox reaction or the ratio of anodic current to cathodic current is equal to 1.

If reaction is irreversible then :

A) The rate of transfer of electron between working electrode and solution redox species is slow.

B) It is further checked by analyzing CV graph , the difference between anodic potential and cathodic potential is greater than 59/n mV where n= number of electron involved in redox reaction or the ratio of anodic current is not equal to 1.