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Sodium

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SODIUM

Sodium is a soft silvery reactive element belonging to the group I of the periodic table. It is characterised by

     

  1. Atomic number 11

    2.  

  2. Relative atomic mass 22.9898

    3.  

  3. Relative density 0.97

    4.  

  4. Melting point 97.5OC

    5.  

  5. Boiling point 892OC

OCCURRENCE

Sodium basically occurs as NaCl in sea water, lakes and rocks. It also occurs as Chile saltpetre (NaNO2).

EXTRACTION

DOWN’S PROCESS

Sodium is mainly extracted by electrolysis in a Down’s cell. In this method fused NaCl is electrolysed in the presence of CaCl2 and KF.

NaCl è Na+ + Cl-

At Cathode

Na+ + e è Na

At anode

2Cl- è Cl2 + 2e

NOTE: In this process only fused NaCl is used. This is because in case, aqueous NaCl is used, H2 will be liberated at the anode because of its high electropositivity.

CHEMICAL PROPERTIES

     

  1. Reducing Action

    2. Al2O3 + 6Na è 2Al + 3Na2O

    3CO2 + 4Na è C + 2Na2CO3

  2. Action of air

    3. H2O

    		 2CO2

    4Na + O2 è 2Na2O è 4NaOH è 2Na2CO3 +2H2O

  3. Action of Water

2Na + 2H2O è 2NaOH + H2

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