Aluminium

Homework – due in Tuesday 13th • Write up yesterdays experiment: The purification of copper by electrolysis – Aim – Method – Diagram – Results – Conclusion – Evaluation

Electrolysis Cathode – negative electrode Anode – positive electrode Electrolyte – A liquid / solution that will conduct electricity

Purifying copper

Copper ions form at the anode Impure copper is used as the anode of an electrolysis cell. The battery pulls electrons off the copper atoms in the anode. • By losing electrons these atoms become copper ions and so the anode slowly ‘dissolves’ away. • Impurities just sink to the bottom as ‘anode mud’.

Copper atoms at the cathode

Opposite charges attract. • Positive copper ions (Cu2+) move towards the negative cathode. At the cathode these ions gain electrons and turn into copper atoms. So, during electrolysis a copper cathode gets thicker.

Uses of aluminium? • • • • • •

Cars, planes, boats and bicycles. Drinks cans Kitchen foil Construction – window frames Cooking utensils CDs

Properties? • Light • Hard (when mixed with other metals in alloys – we will come onto these next week) • Good conductor BUT isn’t it too reactive to be so useful?

Why doesn’t aluminium act like a reactive metal? • Aluminium reacts with oxygen to form a layer of aluminium oxide. – This protects the aluminium from more corrosion

• So aluminium doesn’t seem very reactive.

Electrolysis of Aluminium Oxide

Reducing Iron • Lower than carbon in reactivity series – So we reduce by burning with carbon in a blast furnace.

• blast furnace animation