do now! can you read through the blast furnace equations?

Do now!

Can you read through the blast furnace

equations?

Last lessonThe reduction of

copper oxide using carbon.

Extracting copper from copper oxide

2CuO + C 2Cu + CO2

Today’s lesson

• The extraction of aluminium from aluminium oxide (Bauxite)

Reactivity Series

Electrolysis of aluminium oxide

CO2

Electrolysis of aluminium oxide

Aluminium oxide has a high melting point (2054°C) (EXPENSIVE)

Electrolysis of aluminium oxide

Aluminium oxide will dissolve in molten cryolite which melts at “only” 959°C (CHEAPER)

Electrolysis of aluminium oxide

The molten liquid is put into a large chamber, the walls of which are connected to the negative side of a circuit (cathode). Large positive electrodes (anodes) made of graphite are lowered into the mixture.

Electrolysis of aluminium oxide

Aluminum oxide is an ionic compound. The positive aluminium ions drift to the negative electrode (cathode) and the negative oxygen ions to the positive electrodes (anodes).

Electrolysis of aluminium oxide

At the cathode the aluminium ions gain electrons and become aluminium atoms.

4Al3+ + 12e- 4Al

Electrolysis of aluminium oxide

At the anodes the oxygen ions lose electrons and become oxygen atoms.

6O2- 3O2 + 12e-

Electrolysis of aluminium oxide

The oxygen immediately reacts with the hot graphite to form carbon dioxide. This means the graphite electrodes have to be replaced occasionally as they wear away.

Electrolysis of aluminium oxide

Molten aluminium is tapped from the bottom of the chamber

Electrolysis of aluminium oxide

This all requires LOTS of electricity so is an expensive process.

Electrolysis of Aluminium• Aluminium oxide has a high melting point (2054°C) (EXPENSIVE)• Aluminium oxide will dissolve in molten cryolite which melts at “only” 959°C

(CHEAPER)• The molten liquid is put into a large chamber, the walls of which are connected to the

negative side of a circuit (cathode). Large positive electrodes (anodes) made of graphite are lowered into the mixture.

• Aluminum oxide is an ionic compound. The positive aluminium ions drift to the negative electrode (cathode) and the negative oxygen ions to the positive electrodes (anodes).

• At the cathode the aluminium ions gain electrons and become aluminium atoms.4Al 3+ + 12e- 4Al

• At the anodes the oxygen ions lose electrons and become oxygen atoms.6O2- 3O2 + 12e-

• The oxygen immediately reacts with the hot graphite to form carbon dioxide. This means the graphite electrodes have to be replaced occasionally as they wear away.

• Molten aluminium is tapped from the bottom of the chamber

Maximum two words per drawing - numbers allowed

Homework

Can you complete the “Draw the

sentence” exercise for Wednesday 23rd

September?