ELECTROLYSIS OF ALUMINIUM OXIDE Flashcards
What is the purpose of electrolysis?
To extract a pure substance, often a metal.
What state must the atoms be in for electrolysis to work?
Aqueous or liquid (molten)
Why does the substance used in electrolysis have to either be an aqueous solution or molten?
The ions must be free to move.
Which metals do we have to use electrolysis as a method of extraction?
Aluminium Magnesium Calcium Lithium Sodium Potassium Copper
Why can we not use displacement reactions to extract the likes of aluminium, magnesium and so on?
They are too reactive
What is the anode?
The positively charged electrode, which attracts the anions.
What is the cathode?
The negatively charged electrode, which attracts the cations.
As both metals and hydrogen ions are positively charged, they theoretically both could end up being attracted to the cathode if they were in aqueous solution. How do we determine which one will be collected at the cathode?
The less reactive one. So if hydrogen is more reactive than the metal, then the metal will collect at the cathode and we can tap it off. However, if the metal is more reactive than hydrogen then only hydrogen will be collected at the cathode.
In the extraction of a metal that is more reactive than hydrogen (e.g. sodium), what state must the substance undergoing electrolysis be in?
Molten (liquid)
In the extraction of aluminium by electrolysis, what is the anode made of?
Graphite
In the extraction of aluminium by electrolysis, what is the cathode made of?
Carbon
What is the name of the ore containing aluminium?
Bauxite
What is the aluminium ore dissolved in for the electrolysis of aluminium?
Molten cryolite
Why do we dissolve bauxite in cryolite for the electrolysis of aluminium?
To lower the melting point and hence make the process cheaper
What is the aluminium ion found in the molten cryolite/bauxite mixture during electrolysis?
Al3+
