effect of metal coupling on rusting of iron

 AIM---

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INDEX --1. CERTIFICATE 2. ACKNOWLEDGEMENT 3. OBJECTIVE 4. INTRODUCTION 5. MATERIAL AND EQUIPMENTS 6. PROCEDURE 7. CONCLUSION 8. BIBLIOGRAOHY

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CERTIFICATE ---

This is to certify that the project titled   “study of effect of metal coupling on  rusting of iron” was completed under my   guidance and supervision by Ankit  Choudhary a student of class xii-sci  kendriya vidyalaya no. 4  , within the stipulated time as prescribed   by cbse  __________ Mrs. P. DIXIT

______ Mrs. R. MAHAVAR 

ACKNOWLEDGEMENT— I gratefully acknowledge my  sincere thanks to our chemistry  teacher MRS. R. MAHAVAR   for her remarkable,aluable   guidance throughout this project  work   ANKIT CHOUDHARY   XII-B 

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OBJECTIVE – The goal of this project is to  investigate the effect of metal   coupling on rusting of iron. We will have to study the change  in rusting of iron when an iron  nail is when an iron nail is  coupled with metals more  electronegative than iron and   metals which are less  electropositive than iron.

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INTRODUCTION – Metals and alloy undergoes rusting and   corrosion. The process by which some meals  when exposed to atmospheric conditions i.e, moist air,carbon dioxide, on the surface is  known as coorosion. The compounds   formed are usually Oxides. Rusting is also  a type of coorosion but the term is  restricted to iron or products made from it. Iron is easily prone to  rusting making its surface rough. Chemically, rust is a hydrated ferric oxide  Fe2O3.nH2O. Rusting may be explained by  an electrochemical   mechanism. In the presence of moist air  containing dissolved oxygen or carbon  dioxide, the commercial iron behaves as  if composed of small electrical cells.At  anode of cell, iron passes in to solution as   ferrous ions.

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Fe

Fe(2+)+2e-

The electrons from the above reaction move  towards the cathode and form hydroxyl   ions  H2O + (O) + 2e-

2OH(-)

Under the influence of dissolved oxygen  the ferrous ions and hydroxyl ions interact   from rust,i.e., hydrated ferric oxide. 2Fe2+ +H2O +(O) 2Fe3+ + 6OH-

2Fe3+ + 2OHFe2O3.3H2O (rust) or 2Fe(OH)3

If supply of oxygen is limited the corrosion   product may be black anhydrous magnetite, Fe 3O 4. 

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Methods of preventing corrosion – Some of the methods used to prevent corrosion  are discussed here : 1.Barrier Protection. In this method, a  barrier film is introduced between iron surface  and atmospheric air.The film is obtained by   painting , varnishing etc. 2.Galvanization. The metallic iron isn  covered by a layer of more active metal   such as zinc.The active metal loses  electrons in preference to iron  Zn  Zn2+ + 2eThus, protecting iron from rusting and   corrosion.

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I   N  Materials and Equipments – V  E  Twopetridishes  S  Four test-tubes T  Four iron nails I   Beaker  A Sand paper  Wire gauge T  Gelatin  O  Copper, Zinc and Magnesium  R  strips Y  Potassium ferricyanide solution Phenolphthalein P   R   O   J  E   C  T 

Experimental Procedure — Clean the surface of iron nails with 

the help of sand paper. Wash them  with carbon tetrachloride and dry  on filter paper. Wind a clean zinc strip around one nail, a  clean copper wire around the second and clean  magnesium strip around the third nail.Put all   these three and the fourth nail in Petri dishes so  that they are not in contact with each other. Preperation of Agar-Agar  solution. Heat about three gram of agar  agar in 100 ml of water taken in a beaker until   solution becomes clear.At about 1 ml of 0.1 M   potassium ferri-cyanide solution, 1 ml of    phenol-phthalein solution and stir well the  contents. Fill the petridishes with hot agar agar  solution in such a way that only lower half of   the nails are covered with the liquids.

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Observation -S.no

Meatl pair

Nail rusts or not

1.

Iron-Aluminium

Does not rusts

2.

Iron-Zinc

Does not rusts

3.

Iron-Magnessium

Does not rusts

4.

Iron-Cooper

Nail rusts

Result and Inference

 – 

The

experiment performed on coupling has shown that rusts can be avoided by coupling of iron with more electropositive metal. In this experiment zinc was more electropositive, so it is oxidised leaving iron nail safe. In this way equipments of sevral crores RS ( ). can be saved from rusting

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BIBLIOGRAPHY – COMPREHENSIVE (PRACTICAL CHEMISTRY-XII) WWW.WIKIPEDIA.COM WWW.ENCYCLOPAEDIA.COM WWW.ICBSE.COM NCERT CHEMISTRY TEXTBOOKS - XII

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