Electrolysis of Aluminium Flashcards Preview

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Flashcards in Electrolysis of Aluminium Deck (12)
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1
Q

You produce aluminium from eletrolysing [ ]

A

aluminium oxide

2
Q

You produce aluminium from eletrolysing [ ]

A

aluminium oxide

3
Q

Describe how you get aluminium oxide.

A

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

4
Q

Why is cryolite needed?

A

Al₂O₃ has a very high melting point of over 2000°C - so melting it would be very expensive

5
Q

Cryolite is used to….

A

low temps (and costs)

6
Q

What are the electrodes made of? Why?

A

Carbon (graphite), a god conductor of electricity

7
Q

What is the half-equation at the negative electrode?

A

Al³⁺ + 3e⁻ ->Al

8
Q

What is the half-equation at the positive electrode?

A

2O²⁻ -> O₂ + 4e⁻

9
Q

What is the half-equation at the positive electrode?

A

2O²⁻ -> O₂ + 4e⁻

10
Q

What forms at the -ve electrode?

A

Aluminium

11
Q

What forms at the +ve electrode?

A

Oxygen

12
Q

Why does the positive electrode gave to be replaced every now and again?

A

The oxygen reacts with the carbon in the electrode to produce carbon dioxide. This means the +ve electrodes gradually get ‘eaten away’