effect of metal coupling on rusting of iron

AIM---

study ofeffect ofmetalcoupling onrustng ofiron

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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 onrusting of iron” was completed under myguidance and supervision by AnkitChoudhary a student of class xii-scikendriya vidyalaya no. 4, within the stipulated time as prescribedby cbse

__________ ______Mrs. P. DIXIT Mrs. R. MAHAVAR

ACKNOWLEDGEMENT—

I gratefully acknowledge mysincere thanks to our chemistryteacher MRS. R. MAHAVARfor her remarkable,aluableguidance throughout this projectwork

ANKIT CHOUDHARY

XII-B

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OBJECTIVE –The goal of this project is toinvestigate the effect of metalcoupling on rusting of iron.

We will have to study the changein rusting of iron when an ironnail is when an iron nail iscoupled with metals moreelectronegative than iron andmetals which are lesselectropositive than iron.

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INTRODUCTION –Metals and alloy undergoes rusting andcorrosion. The process by which some mealswhen exposed to atmospheric conditions i.e,moist air,carbon dioxide, on the surface isknown as coorosion. The compoundsformed are usually Oxides. Rusting is alsoa type of coorosion but the term isrestricted to iron or products made from it.Iron is easily prone torusting making its surface rough.Chemically, rust is a hydrated ferric oxideFe2O3.nH2O. Rusting may be explained byan electrochemicalmechanism. In the presence of moist aircontaining dissolved oxygen or carbondioxide, the commercial iron behaves asif composed of small electrical cells.Atanode of cell, iron passes in to solution asferrous ions.

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Fe Fe(2+) +2e-

The electrons from the above reaction movetowards the cathode and form hydroxylions

H2O + (O) + 2e- 2OH(-)Under the influence of dissolved oxygen

the ferrous ions and hydroxyl ions interactfrom rust,i.e., hydrated ferric oxide.

2Fe2+ +H2O +(O) 2Fe3+ + 2OH-

2Fe3+ + 6OH- Fe2O3.3H2O(rust) or 2Fe(OH)3

If supply of oxygen is limited the corrosionproduct may be black anhydrous magnetite,Fe3O4.

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Methods of preventingcorrosion –Some of the methods used to prevent corrosion

are discussed here :1.Barrier Protection. In this method, abarrier film is introduced between iron surfaceand atmospheric air.The film is obtained bypainting , varnishing etc.2.Galvanization. The metallic iron isncovered by a layer of more active metalsuch as zinc.The active metal loseselectrons in preference to ironZn Zn2+ + 2e-

Thus, protecting iron from rusting andcorrosion.

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Materials and Equipments –TwopetridishesFour test-tubesFour iron nailsBeakerSand paperWire gaugeGelatinCopper, Zinc and Magnesium

stripsPotassium ferricyanide solutionPhenolphthalein

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Experimental Procedure —Clean the surface of iron nails withthe help of sand paper. Wash themwith carbon tetrachloride and dryon filter paper.Wind a clean zinc strip around one nail, aclean copper wire around the second and cleanmagnesium strip around the third nail.Put allthese three and the fourth nail in Petri dishes sothat they are not in contact with each other. Preperation of Agar-Agarsolution. Heat about three gram of agaragar in 100 ml of water taken in a beaker untilsolution becomes clear.At about 1 ml of 0.1 Mpotassium ferri-cyanide solution, 1 ml ofphenol-phthalein solution and stir well thecontents. Fill the petridishes with hot agar agarsolution in such a way that only lower half ofthe 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 shownthat rusts can be avoided by coupling of ironwith more electropositive metal. In thisexperiment zinc was more electropositive, so itis oxidised leaving iron nail safe. In this wayequipments of sevral crores RS ( ). can besaved from rusting

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BIBLIOGRAPHY –

COMPREHENSIVE (PRACTICAL CHEMISTRY-XII)

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NCERT CHEMISTRY TEXTBOOKS - XII

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