Wednesday, April 3, 2013

Atomic number 27

Introduction :
The word ‘atomic number 27’ refers to Cobalt which is having the atomic number 27. The number of protons in a nucleus determines the identity of the atom is called as ‘atomic number’.  It is represented by the letter Z. For example a hydrogen atom contains one proton, so the atomic number of hydrogen is one (Z=1) similarly the atomic number of cobalt is 27 (Z=27).
Swedish chemist Georg Brandt (1694–1768) is credited with discovering cobalt (atomic number 27) circa 1735. The word cobalt (atomic number 27) is derived from the German kobalt, from kobold meaning "goblin", a term used for theory of cobalt (atomic number 27) by miners.
Occurrence:
Cobalt (atomic number 27) occurs in copper and nickel minerals and in combination with sulfur and arsenic in the sulfidic cobaltite minerals.

Method of Extraction:


1. Froth flotation process:
It is a process for selectively separating hydrophobic materials from hydrophilic. This is used in several processing industries.
Froth flotation process is based on the principle that the metallic sulphide particles of the ore are preferentially wetted by oil and gangue particles by water.
Froth Floatation Process
                                                                                                 Froth flotation process
In this process, the finely divided ore is added to a large amount of water contained in the tank. Certain oils like pine oil, eucalyptus oil etc, are added.  A current of compressed air is circulated through the water in the flotation tank. The metallic ore particles are preferentially wetted by the oil froth and rise to the surface along with the froth. The gangue material is wetted. Hence it settles at the bottom.
2. Roasting process:
It is a process in which the ores are heated to a high temperature below their melting point in the presence of excess of air. During this process, the moisture escape and the impurities like sulphur, arsenic, etc are oxidized to their volatile oxides. The messes become porous. It is generally carried out in a reverberatory furnace.
                        S +O2 → SO2
                         As  +  O2    As2O3
       Sometimes, the sulphide ore are oxidized to sulphates
                   2ZnS + 3O2 → 2ZnO + 2SO2
Roasting Process
     Roasting process

Applications of Cobalt (atomic number 27)::

  • It is used in batteries.
  • It is used as catalysts.     
  • It is used as a pigment and coloring.
  • It is used in a biological role.
  • It is used for electroplating.
  • It is used for electroplating due to its appearance, hardness, and resistance to oxidation.

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