Extraction Of Metals

Question 1

Give 2 Uses of aluminium and give a reason why it is suitable for each use

Answer 1

Use 1: Manufacture of Aircrafts
Reason: Low density

Use 2: Food containers/ cooking foil
Reason: resistant to corrosion

Question 2

Describe how Aluminium is extracted from bauxite.

Answer 2

1. Bauxite is dissolved in MOLTEN cryolite
2. Cryolite lowers the melting temperature
3. Molten aluminium forms

Question 3

Why do the anodes for the extraction of aluminium have to be replaced regularly?

Answer 3

The carbon electrodes will react with oxygen

Question 4

Describe how zinc oxide is made from zinc sulfide

Answer 4

Zinc sulfide is heat in air/ oxygen

Question 5

Explain the conversion of zinc oxide into zinc and include equations

Answer 5

1. Heat is produced by coke burning in oxygen
   C + O2 -> CO2 (produces heat/ exothermic)
2. C + CO2 -> CO
3. ZnO + CO -> Zn + CO2

Question 6

Explain in terms of electron transfer, why zinc prevents steel from rusting

Answer 6

• zinc is more reactive than iron
• zinc loses electrons
• iron/steel/oxygen/air/water gains electrons
• therefore, iron does not lose electrons (get oxidised)

Question 7

Give 3 properties of transition metals which are not typical of other metals

Answer 7

• catalysts
• form coloured compounds
• have variable oxidation numbers

Question 8

Extraction of aluminium via electrolysis: is the reaction exothermic or endothermic? Explain.

Answer 8

Endothermic, as electrical energy is supplied

Question 9

Explain how the addition of oxygen and calcium oxide removes the impurities in iron. Include an equation of reaction of oxygen and a word equation for a reaction with calcium oxide

Answer 9

1. ) All impurities become oxides
2. ) Silicon dioxide escape as gas
3. ) Silicon (IV) oxide is neutralised by calcium oxide
4. ) Si + O2 -> SiO2
5. ) calcium oxide + silicon (IV) oxide -> calcium silicate