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Submitted to: Submitted by:

Mr. Raj Kumar Manpreet Kaur

+2 ScienceRoll No.

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ACKNOWLEDGEMENT

I take this opportunity to express my gratitude

to Mr. Raj Kumar, Chemistry lecturer for

suggesting this project & his constant advice.

I also thank my parents for helping me from

time to time. It as really impossi!le for me to

complete this project ithout their co"operation.

#ast !ut not the least I ould like to thank Mr.

Rameshar $ass, %rincipal. .'.(.. Model

en. ec. chool, for giving me all the facilities

ithout hich my project ould not have !een

possi!le

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CERTIFICATE OF MERIT

)his is to certify that 'eha *harti of class +

cience during session --"- .'.(..

Model en. ec. chool has su!mitted

satisfactory project on Effect of Metal

Coupling on Rusting of Iron. )he project

report entirely satisfies the practical study of the

certificate of enior chool of %../.*.

Principal Guide Teacher

Mr. Rameshar !ass Mr. Raj Kumar

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"#NT$NTS

1.Theory

2.Protection of Iron articles from Rusting

3.Experiment

4.Theory

5.Apparatus

.!hemicals

".Proce#ure

$.%&ser'ations

(.!onclusions

1). Precautions

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T%$#R&

*ayers of un+ante# po+#ery material are forme# on the surface of

some metals +hen they are expose# to air an# moisture. This is

,no+n as corrosion of metals. If the upper layer is remo'e# more

surfaces gets expose# an# the process of corrosion continues an#

more of the metals gets corro#e#.

In case if iron- this corrosion is ,no+n as Rusting. It is o&ser'e#

that +hen iron articles are expose# to moist air containing !%2 or

%2- they get co'ere# +ith a &ro+n layer of oxi#e ,no+n as Rust

an# the phenomenon of rust formation is ,no+n as Rusting of iron.

Rust is a mixture of ferric oxi#e an# ferric hy#roxi#e forme# &y

the oxi#ation of iron in the presence of moisture an# oxygen.

'Moist.(Iron / %xygen Iron %xi#e 0y#rate# Iron %xi#e

Rust

%xygen an# moisture are essentials for rusting. The presence of

!%2gas an# electrolytes help the process of Rusting. %nce the

process of rusting sets in- it continues &ecause the rust forme# act

as auto catalyst.

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PR#T$"T)#N #* )R#N RT)",$

*R#M R-ST)NG

The materials can &e protecte# from rusting &y a num&er of

metho#s &ut the iron articles are protecte# &y coating their surface

+ith a thin layer of metal +hich is more resistant to corrosion than

iron. or example- iron articles are coate# +ith a thin layer of tin

metal an# the process is ,no+n as tinning. As long as the layer of

tin remains intact- iron article is protecte#. ut if the layer &rea,s

a+ay from some places- the rusting process starts an# is facilitate#

&ecause iron is more electropositi'e than tin.

Accor#ing to Electrochemical Theory of Rusting- nonuniform

surface of iron &eha'es li,e a small electric cell in the presence of

moist air an# car&on #ioxi#e +ith t+o parts of iron piece acting as

electro#es. 6oist air acts as electrolyte.

Iron passes into solution as errous ions e2/ at the ano#e of this

electrochemical cel..

e e2// 2e

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As soon as tin metal is remo'e# from some parts of the iron article-

the remaining tin metal acts as a catho#e an# the electron release#

&y iron mo'e to+ar#s catho#es tin metal to form hy#roxyl ions

+hich reacts +ith iron to form rust.

02% / % / 2e2%0

e3// %0e2%3.302% or 2e %03

This continues till +hole of iron article is corro#e#.

In the mo#ifie# metho# of protection- iron is coate# +ith a more

electropositi'e metal li,e 7inc. uch articles are not affecte# &y

oxygen an# air containing #issol'e# car&on #ioxi#e. It is #ue to the

reason that 8inc is more reacti'e an# passes preferentially into the

solution as 7inc ions 8n// lea'ing iron unaffecte#. Thus the

reaction e e/// 2e#oes not occur an# hence iron is protecte#

from rusting.

The process of co'ering iron articles &y more electropositi'e metal

is ,no+n as metal coupling.

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$periment

To stu#y the effect of metal coupling on

the rusting of iron

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T%$#R&

6etal coupling affects the rusting of iron. If iron nail is couple#

+ith a more electropositi'e metals li,e 7inc- magnesium or

aluminium- rusting is pre'ente# &ut if on the other han#- it is

couple# +ith a less electropositi'e metal li,e copper- rusting

process is facilitate#.

*e/0n couple

8n 8n2// 2e occurs 9 7inc is more electropositi'e than iron

8n 8n e///2e:oes not occur 9 e is less reacti'e than 8n

*e/"u couple

e 9 e2/ / 2e%ccurs 9 iron is more reacti'e than !u 9 Rusting

ta,es place

!u 9 !u2// 2 e:oes not occur 9 !u is less reacti'e than e

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PPRT-S

T+o Petri #ishes +ith co'ers- &ea,er 4)) ml- glass ro#-

+ire gau7e- tripo# stan#- &urner- four iron nails- &are

copper +ire an# 7inc strip.

"%$M)",S

Po+#ere# agaragar 2.5g- +ater- potassium ferricyani#e

solution ).1 6- phenolphyhalein solution )1;.

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PR#"$!-R$

Ta,e 25) ml of #istille# +ater in a &ea,er an# heat to &oiling.

Remo'e the &urner an# a## 2.5 gms of po+#ere# agaragar slo+ly

+ith stirring. A## to it 12 #rops of ).1 6- ? solution

follo+e# &y fe+ #rops of ).1; phenolphthalein solution. Allo+

the solution to cool.

!lean the surface of iron nails +ith the help of san# paper. @ash

them +ith car&on tetrachlori#e an# #ry on filter paper.

@in# a clean 7inc strip aroun# one nail- a clean copper +ire aroun#

the secon# an# clean magnesium strop aroun# the thir# nail. Put all

these an# a fourth nail in Petri #ishes so that they are not in contact

+ith each other.

ill the Petri #ishes +ith hot agaragar solution in such a +ay that

only lo+er half of the nails are co'ere# +ith the liui#s.

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#1S$RT)#NS

. >o. 6etal Pair !olour of the

Patch

>ail rusts or not

1. Iron8inc

2 Iron6agnesium

3 Iron!opper

4 Iron>ail

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"#N",-S)#NS

It is clear from o&ser'ations that coupling of iron +ith more

electropositi'e metal such as 7inc an# magnesium resist

corrosion an# rusting of iron. !oupling of iron +ith less

electropositi'e metal such as copper increases rusting.

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PR$"-T)#NS

1. >ails in a #ish shoul# not touch each other.

2. >ails use# shoul# &e &right an# shining.

3. A## hot agaragar solution in such a +ay that it #oes

not #istur& the nails.

1)1,)#GRP%&

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)he information and knoledge of this project

as gathered from"

Chemistry text!ook for class +, 'C/R)

Comprehensive %ractise Chemistry, +