(Moti Bagh)
(Session: 2024-2025)
CHEMISTRY PROJECT
On
To study the effect of metal coupling on
rusting of iron
Prepared by:
ABHINAV NEERAJ
XII-A
Board Roll no:
CERTIFICATE
This is to certify that Roll No.: ___________ of Class XII,
NAVYUG SCHOOL MOTI BAGH, have worked on the
project titled TO DETERMINE WHICH ANTACID
COULD NEUTRILIZE STOMACH ACID THE MOST
and have completed the project to my satisfaction.
Teacher's Signature
ACKNOWLEDGEMENT
I have taken efforts in this project. However, it would not have
been possible without the kind support and help of many
individuals.
I would like to thank my principal "Mrs. Sunita dewan" and
school for providing me with facilities required to do my project.
I am highly indebted to my chemistry teacher "Mrs. Pamila
Marwaha" for her invaluable guidance which has sustained
my efforts in all stages of this project work.
I am also very thankful to the lab assistant "Mr. Anurag
Verma" for his continuous efforts in developing the project.
I would also like to thank my parents for their continuous support
and encouragement.
My thanks and appreciations also go to my Classmates and to
the peoples who have willingly helped me out with their abilities.
INDEX
Introduction
Electrochemical Mechanism (rusting)
Methods of Prevention of Corrosion
Aim of the project
Requirement
Procedure
Observation
Conclusion
INTRODUCTION
Metal corrosion is the most common form of corrosion. The
corrosion occurs at the surface of the metal in forms of
chemical or electrochemical reactions. This process
significantly reduces the strength, plasticity, toughness and
other mechanical properties of the metaled material.
However, because of the metal and its alloys is still the
most important pipe and structure materials, the cost of
corrosion grows significantly with the growth of industries.
Thus, many scientists 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.
Titanic's bow exhibiting microbial corrosion damage in the form of ‘rusticles’
Similar, electrical potentials may also be developed
between two areas of a component made of a single metal
as result of small differences in composition or structure of
differences in the conditions 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.
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
behaves 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
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 metal
3)Inhibitors; Corrosion inhibitors, such as gas-phase or
violate inhibitors, can be used to prevent corrosion inside
sealed systems. They are not effective when air circulation
disperses them, and brings in fresh oxygen and moisture.
4)Humidity control; Rust can be avoided by controlling the
moisture in the use of silica gel packets to control humidity
in equipment shipped by sea.
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 aluminum rusting is
prevented but if on the other hand , it is coupled with less
electro – positive metals like copper , the rusting is
facilitated.
Apparatus
Two Petri dishes
Four test – tube
Four iron nails
Beaker
Sand paper
Wire gauge
Gelatine
Copper, zinc & magnesium strips
Potassium ferricyanide solution
Phenolphthalein
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 third and a fourth nail in Petri dishes so that
they are not in contact with each other.
Preparation of agar agar solution. Heat about 3gm of agar agar in
100ml of water taken in a beaker until solution becomes clear.
Add about 1ml of 0.1M potassium ferri-cyanide solution, 1ml of
phenol-phthalein solution and stir well the contents.
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.
Keep the covered Petri dishes undisturbed for one day or so.
The liquid sets to a gel on cooling. Two types of patches are
observed around the rusted nail, one is blue and the other is pink.
Blue patch is due to the reaction between ferrous ions and
potassium ferricyanide, to form potassium Ferro-ferricyanide,
KFe [Fe(CN)6] whereas pink patch is due to the formation of
hydroxyl ions which turns colourless phenolphthalein to pink.
Observation
S.No. Metal pair Colour of the Nails Rusts or
patch not
1. Iron-Zinc Pink No
2. Iron-Copper Blue Yes
3. Iron- Pink No
Magnesium
4. Iron-nail Blue Yes
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
Comprehensive (Practical Chemistry – XII)
Internet- www.wikipedia.com, www.encylopedia.com
NCERT Chemistry Textbooks
