SUDHIR MEMORIAL INSTITUTE
DOLTALA,MADHYAMGRAM
CHEMISTRY INVESTIGATORY PROJECT
TO STUDY THE EFFECT OF METAL COUPLING ON RUSTING OF IRON
AISSCE: 2024-25
Name: B. Rajiv Kumar Rao
Class: XII
AISSCE Roll No:
Index
1. Certificate
2. Acknowledgement
3. Aim OF The Project
4. Introduction
5. Procedure
6. Methods of Prevention of Corrosion and Rusting
7. Requirements
8. Observation
9. Conclusion
10.Bibliography
Certificate
This is certify that this CHEMISTRY investigatory project on the topic “To
study the effect of metal coupling on rusting of iron as been completed by
B. RAJIV KUMAR RAO of Class XII under the guidance of in partial
fulfilment of chemistry practical in the curriculum of CBSE , 2024-25
ACKNOWLEDGEMENT
At the outset, I express our gratitude to the Almighty Lord for the divine guidance
and wisdom showered on me tounder take this project . I am immensely grateful to
my beloved Principal for her involvement in this project by providing useful inputs
and my suggestions . I am also thankful to my Chemistry teacher for his guidance
and help to make this project a success . My Parents also played a key role in
shaping up this project nicely and I convey my special thanks to them as we
Aim of the project
In this project the aim is to investigate effect of the metals coupling onthe rusting
of iron. Metal coupling affects the rusting of iron . If the nailis coupled with a
more electro-positive metal like zinc, magnesium oraluminium rusting is
prevented but if on the other hand , it is coupledwith less electro – positive
metals like copper , the rusting is facilitated
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.
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
Fe→Fe2+ + 2e-
The electrons from the above reaction move towards the cathode andform hydroxyl ions
H2O + (O) + 2e-→ 2OH-
Under the influence of dissolved oxygen the ferrous ions and hydroxylions
interact to form rust, i.e., hydrated ferric oxide.
2Fe2+ + H2O + (O) → 2Fe3+ + 2OH-
2Fe3+ + 6OH- → Fe2O3.3H2O or 2Fe(OH)3
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 solutions 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.
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
clear.
beaker until solution Add about 1ml of 0.1M potassium ferric– cyanide solution , 1ml of
becomes
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 colorless phenolphthalein to pink.
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.
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.
Requirements
.Two Petri dishes
.Four test – tube
.Four iron nails
.Beaker
.Sand paper
.Wire gauge
.Gelatin
.Copper, zinc & magnesium strips
.Potassium ferricyanide solution
.Phenolphthalein
Observation
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
