5a) Extraction and Uses of metals

Methods of extraction are linked to the order of reactivity

Only metals that are less reactive than carbon can be extracted by a reduction reaction with carbon- this is done by heating the ore with carbon monoxide. This is because more reactive elements form compounds more readily.

Metals more reactive than carbon have to be extracted using electrolysis. It uses electricity to separate the metal from the other elements in the compound.

Aluminium extraction


Electroylsis is used to remove aluminium from its ore. A catalyst- Cryolite is used to lower the temperature and cost as Al2O3 has a very high boiling point of 2000C and so melting it would be very expensive. It is dissolved into molten cryolite which brings the temperature down to 900C, the electrodes are made of graphite which is a good conductor of electricity.



At the negative electrode (Cathode): Al³⁺ + 3e^- --> Al
At the positive electrode (Anode): 2O₂- --> O₂ + 4e^-

Extracting Iron:

(Blast Furnace) 

Raw materials:

1. Iron ore -----> iron
2. Coke -----> almost pure carbon; reducing iron oxide to iron metal
3. Limestone -----> take away impurities from slag 
4. Air ------> allows the coke to burn 

Reducing Iron ore to Iron:

1. Hot air blasted into the furnace -----> coke burns faster than normal. Raises to 1500C.  
2. Coke burns and produces carbon dioxide:
• Carbon and Oxygen ------> Carbon Dioxide 
• C            +        O2    ------> CO2 
3. Carbon monoxide 
• Carbon dioxide and Carbon -----> Carbon monoxide 
•          CO2          +         C     ----->          2CO 
4. Carbon monoxide then reduces the iron ore to iron
• Carbon monoxide + Iron(II) oxide ------> Carbon dioxide + Iron
•          3CO             +       Fe2O3       ------>        3CO2        +  2Fe 
5. Iron is molten at temperature also dense so goes to the bottom where it's tapped off 

Removing impurities: 

Slag forms as CaO from limestone reacts with rocks (SiO2) 

CaCO3 -----> CaO + CO2 

CaO + SiO2 ------> CaSiO3 (molten slag) 

• Coolen to solid and used for:
• road building 
• fertiliser 

Properties of both Iron and Aluminium

• both dense and shiny 
• have high melting points 
• strong and hard to break 
• are malleable 
• good conductors of heat and electricity 

Uses of Iron

• steel and stainless steel 
• buildings
• car radio 
• railings

Uses of Aluminium

• doesn't corrode so is useful for products that come in contact with water such as drinks cans
• Used in bicycle frames and aeroplanes when the weight has to be very specific