Zinc

Zinc, Zn, is a transition metallic element found in Group IIb of the periodic table.

Atomic Number : 30
Relative Atomic Mass : 65.38

Discovery

Zinc was known from ancient times, when Brass (i.e. an alloy of Copper and Zinc) was used. Lohneyes was the first to apply the term "Zinc" correctly to the metal that we know today in 1697AD.

Occurrence

Zinc is found in different ore forms, including

Zinc Spar, ZnCO3,
Calamine, ZnCO3,
Zinc Blande, ZnS,
Zincite, ZnO,
Willemite, 2ZnO.SiO2,
Franklinite, (ZnFe)O.Fe2O3, and
Zinc Spinel, ZnO.Al2O3.

Extraction

Zinc is extracted using two process :

Roasting, which involves the preparation of zinc oxide and
Reduction, with charcoal which involves the release of the zinc from the oxide.

Properties
Zinc is
- a bright bluish-white metal, which is brittle at room temperature.
- is slowly oxidised in moist air.
- is an good conductor of heat and electricity.
Reactions
- Zinc burns in air at 1000 degC to form a bulky mass of zinc oxide which is known as Philosopher's Wool.
- Zinc reacts with dilute acids, with the liberation of hydrogen.
```
	   Zn   +   H2SO4   ==>   ZnSO4   +   H2	
```
- Zinc in the presence of dilute acid is a powerful reducing agent, probably due to Nascent Hydrogen, H*, liberated in the reaction being a better reducing agent than hydrogen gas.
- Zincis amphoteric and forms salts with alkalis. For example, Zinc dissolves in hot concentrated caustic soda solution with the liberation of hydrogen gas and the formation of sodium zincate.
```
	   Zn   +   2 NaOH   ==>   Na2ZnO2   +   H2	
```
  Uses
  Zinc is in widespread use
  - in the manufacture of electric cells (i.e. Dry Cells),
  - in the manufacture of galvanized iron sheets, to protect against corrosion of the iron,
  - in the manufacture of die-castings objects (e.g. the carburettor in car engines),
  - in alloys,
  - in medicine (as the Oxide), and
  - as a filler for Rubber and in Paints.
    
    Detection and Analysis
    Zinc is detected by heating the material with sodium carbonate on a charcoal block when the zinc oxide produced is coloured yellow when hot and white when cold.
    
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Zinc

Discovery

Occurrence

Extraction

Properties

Reactions

Uses

Detection and Analysis