Sunday, September 25, 2016

                                  

                                 Electrolysis of Brine


                      Electrolysis of concentrated solution of NaCl


          The electrolysis of brine results in hydrogen (H2) and chlorine gas. It  is a large-scale process used to manufacture chlorine (Cl2). The other useful co-product is sodium hydroxide (NaOH).



      At the cathode, water is reduced to hydroxide ion and hydrogen gas. (The more reactive a metal, the less readily its ion is reduced on the electrode surface.) 
At the anode, chloride (Cl-) ions are preferentially oxidized to chlorine.

Reduction at Cathode :
                  2H2O(l) + 2e   =   H2(g)  + 2OH-(aq) 

Oxidation at Anode : 
                   2Cl(aq)  =  Cl2(g) + 2e 

Overall reaction :

     2H2O(l)  + 2Cl(aq)  =  2OH(aq)  + H2(g) + Cl2(g) 
             
              (The sodium ions are spectator ions)








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