intro, result,observation of metal coupling

1. TOPIC : Effect of metal coupling on
the rusting of iron
b.c. PUBLIC SCHOOL
2016-2017
SUBMITED TO:-
MRS. anju MAM
SUBMITED BY:-
BHARATa ramCHOUDHARY

2. certificate
.
This is to certify that Bharata Ram Choudhary, a student of
class XII science has successfully completed the research
project on the topic “Effect of metal coupling on rusting of
iron” under the guidance of Mrs. ANJU SHARMA (Subject
Teacher).
This project is absolutely genuine and does not indulge in
plagiarism of any kind.
The references taken in making this project have been declared
at the end of this report.
Signature Signature
(Subject Teacher). (Principal Mam)

3. I feel proud to present my Investigatoryproject in Chemistry on
the topic “Effect of metal coupling on rusting of iron”.
This project wouldn’t have been feasible without the proper and
rigorous guidance of my Chemistry teacher Mrs. Anju Sharma
who guided me throughout this project in every possible way.
An investigatory project involves various difficult lab
experiments which have to be carriedout by the student to
obtain the observations and conclude the report on a
meaningfulnote. These experiments are very critical and in the
case of failure, may result in disastrous consequences.Thereby,
I would like to thank mam for guiding me on a step by step
basis and ensuring that I completed all my experiments with
ease.
Rigorous hard work has been put in this project to ensure that it
proves to be the best. I hope that this project will prove to be a
breeding ground for the next generation of students and will
guide them in every possible way.
BHARAT CHOUDHARY
ACKNOWLEDGEMENT

4. 1. Introduction
2. Objective of project
3. Aim
4. Requirements
5. Theory
6. Procedure
7. Observation
8. Result
9. Bibliography
10. Remarks
CONTENTS

5. 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 hydratedferric oxide Fe2O3.nH2O.
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.
Fe → Fe2+
+ 2 e−
The electrons from the above reaction move towards the
cathode and form hydroxyl ions
H2O + (O) + 2 e−
→ 2OH-
INTRODUCTION

6. Under the influence of dissolved oxygen the ferrous ions and
hydroxyl ions interact to form rust, i.e., hydrated ferric
oxide.
2Fe2+
+ 2 H2O + (O) +2e-
→2Fe3
+
+ 2OH-
2Fe3+
+ 6OH-
→ Fe2O3.3H2O or 2Fe(OH)3
(RUST)
If we supply of oxygen is limited the corrosion product may
be black anhydrous magnetite,Fe3O4.
Methods of Prevention of Corrosion and Rusting
1. Barrier protection : In this method a barrier is placed
between metal and atmosphere. This is actually done by
coating the metals surface with paint oil or grease. The
barrier avoids the direct contact of the metal surface with
the environment and hence prevents corrosion.
2. Galvanization : In this method the iron object is covered
with a thin coating of metal like zinc which is more reactive
than iron. Here the active metal which is coated will act as
anode and undergo oxidation in preference to iron. The
process of coating iron objects with zinc is
called galvanization.
Zn → Zn2+
+ 2e-

7. In thisprojectthe aim is to investigate effectof the
metals coupling on the rusting of iron. Metalcoupling
affects the rustingof iron . If the nail is coupledwitha
more electro-positive metal like zinc,magnesiumor
aluminiumrustingis preventedbutif on the other
hand , it is coupled with less electro – positive metals
like copper, the rusting is facilitated.
Objective of project

8. To study the effect of
metal coupling on
rusting of iron.
AIM

9. 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
REQUIREMENTS

10. • Corrosion is a serious problem of some metals
like iron, zinc, aluminium and alloys like brass
which are commonly used in day to day life.
• Apart from reducing the life of articles made
up of these metals or alloys the chemical
substances formed out of corrosion have serious
public health problems.
• Replacement of machines or their parts and
many other articles in industrial and public dealing
lead to huge expenditure.
• Hence, how to reduce or avoid corrosion of
articles made up of metals or alloys has been a
major subject of study in the field of chemistry and
electro-chemistry.
THEORY

11. 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
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,
KFe[Fe(CN)6] where pink patch is due to the
PROCEDURE

12. formation of hydroxyl ions which turns colourless
phenolphthalein to pink.
This all information taken from :-
1. Practical book of chemistry
2. www.google.com
3. www.wikipedia.com
4. NCERT chemistry textbook
BIBLIOGRAPHY

13. REMARKS

14. S.No. Metal Pair Colour of the
patch
Nails rusts
or not
1 Iron- Zinc Blue No
2 Iron -Magnesium Blue No
3 Iron- Copper Pink Yes
4 Iron – Nail Pink Yes
OBSERVATION

15. 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.
CONCLUSION

16. Two types of patches are observed around the
rusted nail
1. One is blue- due to the formation of
potassium Ferro-ferricyanide
2. Pink patch is due to the formation of hydroxyl
ions which turns colorless phenolphthalein to pink
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.
RESULT