Notes

What Is Electrolysis?

Don't be shocked, but molten ionic compounds don't just stop at conducting electricity. They use it for chemical reaction!

“Cher, what is electrolysis? It doesn’t even make sense!”
“Why here got electrons there don’t have??”
“How do I even know what happens???”

Sounds familiar? Electrolysis giving you the shock of your life? Alright, calm down, we are here to help, no charge 😉

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This will be the first set of electrolysis notes for you to understand the concept of electrolysis. We need to first get the basics, before we can solve the questions.

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Remember we learnt that ionic compounds conduct electricity only in molten or aqueous states, but not in solid state. But how did scientists prove this?

The first diagram shows that electricity can flow in the circuit with platinum electrode in it, since the lightbulb is lighted. This makes sense because platinum is a metal and metals are conductors of electricity (think sea of delocalized electrons).

Comparing the second and third diagram, we conclude that electricity CAN FLOW THROUGH molten ZnCl2 but not solid ZnCl2. We can call the molten ZnCl2 electrolyte.

This also makes sense because we learnt in sec 3 that molten ionic compounds conduct electricity because they have MOBILE IONS.

But have you ever wondered HOW mobile ions conduct electricity?

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Scientists figured, there are only two possibilities:

Possibility 1

Possibility 1. The ions take in the electricity (carry it in their shell) from one electrode. With the electricity, the mobile ions swim to the other electrode. The ions then unload the electricity onto the other electrode, completing the circuit.  

Possibility 2

Possibility 2. The ions split the work. Some ions will be at one electrode taking in electricity, while other ions will be at the other electrode giving out electricity. This is possible as electricity = flow of electrons and ions have electrons.

If you were the ions, which method would you choose? To me, version 2 seems like the obvious choice: the ions don’t even have to move and the circuit is complete!

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And that folks, is what electrolysis is all about – how molten ionic compounds conduct electricity.
To do so, ions split themselves into two groups, one group in charge of taking in electrons and putting it into its electron shell, the other group in charge of giving electrons from its own electron shell. This way, the circuit is complete (electrons flowing out from negative terminal of battery, and back to the positive terminal of battery)!