Electrolysis of Aluminium Flashcards
You produce aluminium from eletrolysing [ ]
aluminium oxide
You produce aluminium from eletrolysing [ ]
aluminium oxide
Describe how you get aluminium oxide.
Aluminium’s a very abundant metal, but is always found naturally in compounds
Its main ore is bauxite and after mining and purifying, a white powder is left
This is pure aluminium oxide, Al₂O₃
Why is cryolite needed?
Al₂O₃ has a very high melting point of over 2000°C - so melting it would be very expensive
Cryolite is used to….
low temps (and costs)
What are the electrodes made of? Why?
Carbon (graphite), a god conductor of electricity
What is the half-equation at the negative electrode?
Al³⁺ + 3e⁻ ->Al
What is the half-equation at the positive electrode?
2O²⁻ -> O₂ + 4e⁻
What is the half-equation at the positive electrode?
2O²⁻ -> O₂ + 4e⁻
What forms at the -ve electrode?
Aluminium
What forms at the +ve electrode?
Oxygen
Why does the positive electrode gave to be replaced every now and again?
The oxygen reacts with the carbon in the electrode to produce carbon dioxide. This means the +ve electrodes gradually get ‘eaten away’
