What does "be chemically reversible, but not electrochemically reversible" mean?
Is "Chemically reversible" different from "Electrochemically reversible" ?
What is the difference ? Please let me know. Thank you.
Being chemically reversible is the technical application given to chemical equations that are basically in equilibrium with each other. In early chemistry, chemical reactions were basically thought to proceed in one direction only, you mix this with that and you get product A and B. Around the 19th century, it was discovered that some chemical reactions not only went from left to right, as was originally thought, but they also "rebounded", the ions dissociated again, and the original reactants were reproduced. Such a reaction would be depicted as such:
aA + bB <----> bA + aB
This equation means there is just as much of the left side of the equation going on as there is the right side of the equation, thus the term "equilibrium".
Electrochemically reversible would indicate the use of an electric current to reverse a chemical reaction. The hydrolysis of water, H2O, is an example of an equation that is electrochemically reversible:
H2O (electric current) ---> H2 + O2
So an equation that is "not electrochemically reversible" would be one that does not reverse the ions with the passage of an electric current.