Chemistry Project on Metal coupling in rusting of Iron

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Study of the Effect of Metal Coupling on the Rusting of Iron

AISSE – 2010 CHEMISTRY PROJECT

Study of the Effect of Metal                     Coupling on the Rusting of Iron

¡PRESENTED BY GOURAV DHIMANKAR

¡XII – A (SCIENCE)

¡CBSE ROLL NO. -

Certification :

It has been certified that Gourav Dhimankar having CBSE Roll No. 5456340

Studying in XII-A (Science), during the academic year 2009-10 has completed a project

on the Study of the Affect of Metal Coupling on the Rusting of Iron and has given satisfactory account of this in his project report

Shri A.K Gupta                External Examiner

PGT Chemistry                     Signature                    Signature

Declaration :

I , Gourav Dhimankar of Class XII A (Science) , Kendriya Vidyalaya Ballygunge , declare that the following project on the Study of the Affect of Metal Coupling on the Rusting of Iron has been accomplished under the able guidance of our Chemistry Teacher , Shri A.k Gupta

Teacher Signature

Kendriya Vidyalay Ballygunge

Date :

Acknowledgement :

I would like to express my gratitude to Shri A.K Gupta, our chemistry teacher, whose help and encouragement made this project possible.

I would also like to thanks Mr. Vaidya, the Lab Assistant for his help during the completion of this project.

Gourav Dhimankar

XII A (Science)

Kendriya Vidyalaya Ballygunge

Index :

Introduction…………………………6

Electrochemical Mechanism (rusting)…...7

Methods of Prevention of Corrosion…….8

Aim of the project……………………9

Requirement…………………………10

Procedure……………………….….11

Observation……………………......12

Conclusion………………………….13

Introduction:

Metals and alloys undergo rusting and corrosion. The process by which some metals when exposed to atmospheric condition i.e., moist air, carbon dioxide form undesirable compounds on the surface is known as corrosion, The compounds formed are usually oxides . Rusting is also a type of corrosion 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

Titanic's bow exhibiting microbial corrosion damage in the form of 'rusticles'

Rusting an Electrochemical Mechanism ;

Rusting may be explained by an electrochemical mechanism. In the presence of moist air containing dissolved oxygen or carbon dioxide, the commercial iron behave as if composed of small electrical cells. At anode of cell, iron passes into solution as ferrous ions. The electron moves towards the cathode and form hydroxyl ions. Under the influence of dissolved oxygen the ferrous ions and hydroxyl ions interact to form rust, i.e., hydrated ferric oxide.

Methods of Prevention of Corrosion and Rusting

Some of the methods used to prevent corrosion and rusting are discussed here :

1) Barrier Protection ; In the 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 is covered by   a layer of more reactive metal such as zinc. The active metal losses electrons in preference of iron. Thus, protecting from rusting and corrosion.

Galvanized Metals

Aim of the project;

In this project the aim is to investigate effect of the metals coupling on the rusting of iron. Metal coupling affects the rusting of iron . If the nail is coupled with a more electro-positive metal like zinc, magnesium or aluminium rusting is prevented but if on the other hand , it is coupled with less electro – positive metals like copper , the rusting is facilitated.

Requirement :

1)Two Petri dishes

2) Four test – tube

3) Four iron nails

4) Beaker

5) Sand paper

6)Wire gauge

7) Gelatin

8) Copper, zinc & magnesium strips

9)Potassium ferricyanide solution

10)Phenolphthalein

Procedure  ;

1)At first we have to clean the surface of         iron nails with the help of sand paper.

2) After that we have to wind zinc strip around one nail, a clean copper wire around the second & clean magnesium strip around the third nail. Then to put all these three and a fourth nail in Petri dishes so that they are not in contact with each other.

3) Then to fill the Petri dishes with hot agar agar solution in such a way that only lower half of the nails are covered with the liquids .Covered Petri dishes for one day or so.

4) The liquids set to a gel on cooling. Two types of patches are observed around the rusted nail, one is blue and the other pink. Blue patch is due to the formation of potassium ferro-ferricyanide where pink patch is due to the formation of hydroxyl ions which turns colourless phenolphthalein to pink.

Observation ;

S.No. Metal Pair Colour of the patch Nails rusts or not
1 Iron- Zinc
2 Iron -Magnesium
3 Iron- Copper
4 Iron - Nail

Conclusion :

It is clear from the observation that coupling of iron with more electropositive metals such as zinc and magnesium resists corrosion and rusting of iron. Coupling of iron with less electropositive metals such as copper increases rusting.

Bibliography:

For our project we have taken help from following sources ;

1) Comprehensive (Practical Chemistry – XII)

2) Internet- www.wikipedia.com, www.encylopedia.com

3) NCERT Chemistry Textbooks

(Note –Need any help contact - [email protected])


INDEX 1. Certificate 2. Acknowledgement 3. Objective 4. Introduction 5. Materials and equipments 6. Procedure Certificate This is to certify that the project titled “Study of effect of metal coupling in rusting of Iron” was completed under my guidance and supervision by Ashish Pandey a student of XII-Sci. ,Prabhat Senior Secondary Public School within the stipulated time as prescribed by CBSE. ______________ ______________ Mrs.Neena Nigam Mr.Harsh Mishra Principal Teacher ACKNOWLEDGEMENT I gratefully acknowledge my sincere thanks to our chemistry teacher Mr. Harsh Mishra for his remarkable, valuable guidance and supervision throughout the project work. I also express my thanks to my parents for their valuable support and for all sort of assistance for completing he project. ASHISH PANDEY XII-Science OBJECTIVE The goal of the project is to investigate effect of metal coupling on the rusting of iron. Metal coupling effects the rusting of iron. We will have to study the change in rate of rusting when an iron nail is coupled with metals more electro- positive than iron and with metals which are less electro-positive than iron. INTRODUCTION Metals and alloys undergo rusting and corrosion.The process by which some Metals when exposed to atmospheric conditions i.e.,moist air, carbon dioxide form undesirable compounds on the surface is known as Corrosion. The compounds formed are usually oxides. Rusting is also a type of corrosion 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 Fe2 O3 .nH2 O. 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. Fe Fe2+ +2e- The electrons from the above reaction move towards the cathode and form hydroxyl ions H2 O + (O) + 2e- 2OH- Under the influence of dissolved oxygen the ferrous ions and hydroxyl ions interact from rust,i.e., hydrated ferric oxide. 2Fe2+ +H2 O +(O) 2Fe3+ + 2OH- 2Fe3+ + 6OH- Fe2 O3 .3H2 O (rust) or 2Fe(OH)3 If supply of oxygen is limited the corrosion product may be black anhydrous magnetite, Fe3 O4 . 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+ + 2e- Thus, protecting iron from rusting and corrosion. MATERIALS AND EQUIPMENTS  Two petridishes  Four test-tubes  Four iron nails  Beaker  Sand paper  Wire gauge  Gelatin  Copper, Zinc and Magnesium strips  Potassium ferricyanide solution  Phenolphthalein EXPERIMENTAL PROCEDURE 1. Clean the surface of iron nails with the help of sand paper. Wash them with carbon tetrachloride and dry on filter paper. 2. 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. 3. 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. 4. Fill the petridishes with hot agar agar solution in such a way that only lower half of the nails are covered with the liquids. 5. Keep the covered petridishes undisturbed for one day or so. 6. The liquid sets to a gel on cooling .Two types of patches are observed around the rusted nail,one is blue and the other pink.Blue patch is due to the reaction between ferrous ions and potassium ferricyanide to form potassium ferro-ferricyanide KFe[Fe(CN)6 ] where as pink patch is due to the formation of hydroxyl ions which turns colourless phenolphthalein to pink.

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