Catalytic properties of transition metals

 

Catalytic properties of transition metals

    ·      Good catalysts due to

   a.  the presence of free valencies and  variable oxidation states

   b.  these provide surface for reaction 

  

some Examples are as

    ·      Iron (III) catalyses the reaction between iodide and persuphate ions-

2I^- +   S₂O₈^2- -------> I₂ + 2SO₄^2-

Explanation of catalytic action of Fe³⁺ in above reaction

Step-1 

2Fe³⁺ + 2I^-    -------> 2Fe²⁺ + 2I₂

Step-2

 2 Fe²⁺ +   S₂O₈^2- -------> 2Fe³⁺   + 2SO₄^2-

in this catalytic action of Fe, Fe shows variable oxidation state i.e. Fe³⁺ changes into Fe²⁺ Again into Fe³⁺

    ·      Pt-used as a catalyst in the manufacture of H₂S0₄.       

    ·      Fe-used as a catalyst in the manufacture of NH₃ by Haber process. A small amount of molybdenum is added as a promoter.

    ·      Ni.-used as a catalyst in the hydrogenation of oils.

    ·      V₂0₅-used as a catalyst for the oxidation of S0₂ into S0₃ for the manufacture of H₂S0₄ in the contact process.

    ·       Mn02-used as a catalyst in the decomposition of KCI0₃ for preparation of oxygen.