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The Chemical Formula for Aluminum

May 6, 2013

Aluminum belongs to group 13 of the periodic table. It was first discovered by Wohler in 1827. It is the third most abundant element in the earths crust. The atomic number of aluminum is 13. Aluminum forms a tri-positive ion i.e. Al3+. It is less electropositive than sodium and magnesium.

PROPERTIES OF ALUMINUM

PHYSICAL PROPERTIES

1) Aluminum is a soft silvery white metal. The fresh metal on exposure to moist air loses its shining due to formation of oxide layer on its surface.

2) It is very light metal with specific gravity equal to 2.70.

CHEMICAL PROPERTIES OF ALUMINUM

(1) Action of air.

(a) Aluminum is not affected by dry air but in moist air a thin film of oxide is formed on its surface.

(b) It burns with oxygen with a brilliant white light with the evolution of heat

4Al +3O2 —-> 2Al2O3

(2) Action of water: Aluminum is not affected by pure cold water. However, saline water corrodes rapidly especially when it is hot. It decomposes boiling water. In the form of amalgam, it reacts more easily and rapidly with water and can decompose it even in cold.

2Al + H2O —-> 2Al (OH) 3+ 3H2

(3)Action of acids: Aluminum dissolves in dilute hydrochloric acid forming aluminum chloride with the evolution of di-hydrogen gas.

2Al + 6HCl  —-> 2AlCl3 + 3H2

Aluminum is not attacked easily by dilute sulphuric acid. This probably is due to insolubility of oxide layer (present on its surface) in the acid. However, it dissolves in hot and concentrated sulphuric acid to form sulphur dioxide.

2Al + 6H2SO4 —-> Al2 (SO)3 + 2SO2 + 6H2O

USES OF ALUMINUM

1)     Auminium is used for making electrical transmission cables.

2)     Aluminum powder is used as a reducing agent inj Goldschmidt aluminothermic process and thermite welding.

3)     It is used in making household utensils and novelty articles.

4)    Aluminum foil is used for wrapping soaps, cigarettes, confectionary, etc.

5)     It is used for making silvery paints for covering iron and other materials.

6)     It is used as dexidiser for removing blow holes in metallurgy.

7)     Due to low density, good thermal and electrical conductivity and resistance to corrosion, aluminium is used for making several alloys which are extensively used in automobile and automobile industries.

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