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Extraction of Metals…read more

Slide 2

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Sulphides to Oxides
· Metals are usually found in ores combined with oxygen or sulphur
· The oxygen has to be removed to obtain the metal through a
reduction reaction
· Heat the sulphide ore in in air-roasting
· ZnS + ½ O2 ZnO + SO2
· SO2 is an acid gas and contributor to acid rain
· So it's collected and converted into sulphuric acid…read more

Slide 3

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Choosing a Reducing Agent
· Coke- impure carbon
· Problems- at high temperatures more reactive metals form carbides
· Hydrogen- used to extract Tungsten
· Flammable, so it's a last resort
· Reactive metals- electrolysis
· A more reactive metal…read more

Slide 4

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Extracting Iron-Blast Furnace
· Fe is found in the ore magnetite, Fe3O4 and haematite, Fe2O3.
· The Process
· Coke burns in hot air generating heat
· CO2 is formed which reacts with more carbon to form CO
· C + O2 CO2
CO is the reducing agent
· CO2 + C 2CO
· Fe2O3 + 3CO 2Fe + 3CO2…read more

Slide 5

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Extracting Copper
· Cu ore is converted into a solution containing Cu2+ ions
· This is done by spraying the ore with dilute acid containing a
bacterium, Thiobacacillus Ferrooxidants
· The Cu is then extracted by reduction with scrap iron
Cu2+ + Fe Cu + Fe2+…read more

Slide 6

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Extracting Aluminium- Electrolysis
· Bauxite ore= Al2O3
· The oxide is dissolved in molten cryolite, Na3AlF6
· Al is formed at the negative electrode(cathode)
· 2Al3+ + 6e- 2Al
· O2 is formed at the positive electrode(anode)
· 3O2- 1½ O2 + 6e-
· Overall: Al2O3 1½ O2 + 2Al
· The positive electrode is made from carbon which the oxygen reacts
with to make CO2, meaning the electrodes has to be regularly
replaced…read more

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