AFNAAN QURESHI
XII– A
LITTLE FAIRY PUBLIC SCHOOL

 Certificate
 Acknowledgement
 Introduction
 Mechanism of corrosion of metal
 Rusting : An electrochemical mechanism
 Methods of prevention of corrosion of metals
 Aim of this project Aim of this project
 Apparatus
 Procedure
 Images
 Observation
 Conclusion
 Bibliography

This is to certify that AFNAAN QURESHI of class XII – A has made this
project titled ‘Study of the effect of metal coupling on the rusting of iron’
under the supervision and guidance of Mrs. MEENAKSHI KHURANA
MAAM. The works speaks about the sincere efforts of the student and
thinks it quite satisfactory and should be accepted for evaluation.thinks it quite satisfactory and should be accepted for evaluation.
External examiner sign.
__________________
Internal examiner sign.
__________________

I would like to express my special thanks of gratitude to my teacher
Mrs. MEENAKSHI KHURANA MAAM who gave me the
golden opportunity to do this wonderful project on the topic
‘Study of the effect of metal coupling in the rusting of iron’
which also help me in doing lot of research and I came to
‘Study of the effect of metal coupling in the rusting of iron’
which also help me in doing lot of research and I came to
know about so many new things I am really thankful to them.
Secondly, I would also like to thank my parents and friends who
helped me in finalizing this project within the limited time
frame.
It was a great pleasure while making such an interesting project.

Metal corrosion is the most common form of corrosion. The corrosion occurs at
the surface of the metal in the form of chemical or electrochemical reactions.
This process significantly reduces the strength, plasticity, toughness and
other mechanical properties of the metallic material. However, because of the
metal its alloy is still the most important pipe and structure material, the
cost of corrosion grows significantly with the growth of industries. Thus
many scientist focus on the research of corrosion control in order to reducemany scientist focus on the research of corrosion control in order to reduce
the cost of replacing the rusting metal material. Nowadays, there are mainly
two corrosion control methods that are very
popular in the world. One is impressed
current and another is sacrificial anode
cathode protection system. In this project, we
will focus on the mechanism and
application of the sacrificial anode cathode
protection system.

General principle of corrosion :
Reaction is the fundamental reaction during the corrosion process,
which the electron can flow from certain areas on the metal surface to
other areas through a solution which can conduct electric current.
Basically, both anode and cathode reaction have to balance each other
out, resulting in a neutral reaction. Both anode and cathode reactionout, resulting in a neutral reaction. Both anode and cathode reaction
occur simultaneously at the same rates. What’s more, the site of these
electrodes may consists of either two different kinds of metals, or they
may be on different areas of the same piece of metal, resulting a
potential difference between the two electrodes, so that the oxidation
reaction of the metal at the anode and formation of negative ions at
the cathode can take place at the same time.

Similarly, electrical potential may also be developed between two areas of a
component made of a single metal as a result of small differences in compositioncomponent made of a single metal as a result of small differences in composition
or structure or of differences in a condition to which the metal surface is
exposed. That part of a metal which becomes the corroding area is called the
“anode” ; that which acts as the other electrode of the battery is called “cathode”
which does not corrode, but is an important part of the system. In the corrosion
systems commonly involved, with water containing some salts in solution as the
electrolyte. Corrosion may even take place with pure water, provided that oxygen
is present. In such cases oxygen combines with the hydrogen generated at the
cathode, removing it and permitting the reaction to go on.

Rustingmay be explainedby 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 cell. At anode of cell, iron passes into solution as ferrous
ions. The electron moves towards the cathode and form hydroxyl
ions. Under influence of dissolved oxygen, the ferrous ions and
ions. The electron moves towards the cathode and form hydroxyl
ions. Under influence of dissolved oxygen, the ferrous ions and
hydroxyl ions interact to form, i.e., hydrated ferric oxide.

 Some methods of preventions in our daily life are :-
1) Barrierprotection: 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 is covered
by a layer of more reactive metal such as zinc.
The active metal losses electrons in peferen-
-ces of iron. Thus protecting from rusting
and corrosion.

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 more electro-positive metal like zinc,
magnesium or aluminum rusting is prevented butmagnesium or aluminum rusting is prevented but
if on the other hand , it is coupled with electro-
positive metals like copper, the rusting is
facilitated.

1) Two Petri dishes
2) Four test tube
3) Four iron nail
4) Beaker
5) Sand paper
6) Wire gauge6) Wire gauge
7) Gelatin
8) Copper, Zinc and Magnesium strips
9) Potassium ferricyanide solution
10) Phenolphthalein

1) At first we have to clean surface of iron nails with the help of
sand paper.
2) After that we have to wind zinc strips around one nail, a clean
copper wire around the second and clean magnesium strip
around the third nail. Then to put all these three nails and a
fourth nail in Petri dishes so that they are not in contact with
each other.
3)
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.
4) Keep the Petri dishes for one day or so on.
5) The liquids set to g n cooling. Two types of patches are observed
around the rusted nail, one is blue and the other pink. Blue
patch is due to formation of potassium ferricyanide where pink
patch is due to the formation of hydroxyl ion which turns
colorless phenolphthalein to pink.

S.No. Metalpair Colour of thepatch Nails rustor not
1. Iron-Zinc Pink No
2. Iron-Copper Blue Yes
3. Iron-Magnesium Pink No
4. Iron-Nail Blue Yes4. Iron-Nail Blue Yes

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

 CBSE NCERT book of chemistry of class 12
 https://www.google.co.in
 https://www.google.co.in/imghp?hl=en&tab=wi
 slideshare.com slideshare.com
 www.wikipedia.org