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

                                               CHEMISTRY PROJECT

                    Study of the Effect of Metal  Coupling on the Rusting of Iron
                                 PRESENTED BY    .........(name)    ......
                                           XII – A (SCIENCE)
                                               CBSE ROLL NO. –


 Certification : 

It has been certified that ......(name).............. having CBSE Roll No. ...................
Studying in XII-A (Science), during the academic year 20.... -...... 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
         .........................                                                                         External Examiner
              PGT Chemistry                                                                        ......................  
                 Signature                                                                                  Signature

 Declaration :
 I , ........(name)................ of Class XII A (Science) , ......( school)........... , 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 , ........................

Teacher Signature
.................(school)
Date :...................


 Acknowledgement :
I would like to express my gratitude to ........................, our chemistry teacher, whose help
 and encouragement made this project possible.
I would also like to thanks ......................, the Lab Assistant for his help during the completion
 of this project.
........(name)......
XII A (Science)
.....(school)...........


 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