- The arrangement of metals in the decreasing order of their reactivity is known as activity series.
- In the activity series the most reactive are placed at the top and the least reactive at the bottom.
- For any two metals in the series, the metal placed higher in the series can displace the other metal from its salt solution.
- Oxides of highly reactive metals like magnesium and aluminium are not reduced easily either by hydrogen, carbon or carbon monoxide.
- Metals that are placed below copper do not rust easily because of their low reactivity.
Metals are available in the form of their ores.
- Methods of extraction are based on the reactivity of metals.
Methods of extraction
Reduction is the process of removal of oxygen for extraction of metals from their oxide ores.
The common reducing agents used for reduction of metal oxides are:
- Carbon monoxide
Electrolysis is the process of decomposition of a substance by passing electricity through it in a molten or dissolved state.
Electrolysis of fused magnesium chloride gives magnesium at cathode and chlorine at anode
Important ores of aluminium are:
- Bauxite, represented by the formula Al2O32H20
- Corundum, represented by the formula Al2O3 , and
Cryolite, with the formula Na3AlF6.
Bauxite is the principal ore of aluminium. The extraction of aluminium from bauxite involves three steps:
- The purification of bauxite using Bayer’s process.
- The electrolytic reduction of anhydrous Al2O3 by Hall and Herault’s process.
- The last step is the purification of impure aluminium by Hoope’s process
Aluminium is used in :
- Manufacture of automobile components
- Construction process
- Manufacture of electric wires
- Packing medicines and pharmaceutical products
- Manufacture of soft drink cans and espresso coffee makers
- Manufacture of utensils
An alloy is a homogeneous mixture of solid solution of two or more metals or metals with non-metals.
Duralumin is a light and tensile alloy of aluminium.
Duralumin is used in the making of air craft frames, pressure cookers
Magnalium is an alloy of aluminium and magnesium
- Magnalium is used in the making of balances because of its high structural strength and resistance to corrosion.
It is also used in the making of optical instruments like cameras and microscopes due to its light weight and resistant to corrosion