chemistry investigatory project - study of constituent of alloys

8/10/2019 CHEMISTRY INVESTIGATORY PROJECT - STUDY OF CONSTITUENT OF ALLOYS

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CERTIFICATE

Thisis to certify that BENEDICT ISAAC of Class XII-A with Reg no:

. has successfully completed the Chemistry project titled

STUDY OF CONSTITUENTS OF ALLOYS in partial fulfilment of

curriculum of ALL INDIA SENIOR SECONDARY EXAM(CBSE). This

project was carried out in the school laboratory of K.V. Pangode

during the academic year 2014-15.

Internal Examiner External Examiner

Teacher in charge Principal


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Acknowledgement

I take this opportunity to express my gratitude in few words

and respect to all those who helped me in the completion of this

project. The successful completion of any task would be

incomplete without mentioning the names of those persons who

helped to make it possible.

It is my humble pleasure to acknowledge my deep senses of

gratitude and heartfelt indebtedness to my teacher Smt. Meena

for her valuable support, constant help and guidance at each and

every stage, without which this project would not have come

forth.

I also register my sense of gratitude to our Principal, my

teacher Shri K. B. K Unnithan, for his immense encouragement

that has made this project successful.

I would also like to thank my friends and family for their

endless support without which I could not have completed this

work in time.


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INDEX

Sl no: Title Page no:

1. Certificate 02

2. Acknowledgement 03

3. Introduction 05

4. Experiment 1Brass 09

5. Experiment 2-Bronze 12

6. Conclusion 17

7. Bibliography 18


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Introduction

An alloy is a mixture ormetallicsolid solution composed of

two or moreelements.Complete solid solution alloys give single

solidphase microstructure, while partial solutions give two or

more phases that may or may not behomogeneous in

distribution, depending on thermal (heat treatment) history.

Alloys usually have different properties from those of the

component elements.

The term alloy is used to describe a mixture of atoms in

which the primary constituent is a metal. The primary metal is

called the base, the matrix, or thesolvent. The secondary

constituents are often called solutes. If there is a mixture of only

two types of atoms, not counting impurities, such as acopper-

nickel alloy, then it is called a binary alloy.If there are three types

of atoms forming the mixture, such as iron, nickel and chromium,

then it is called a ternary alloy.An alloy with four constituents is

a quaternary alloy,while a five-part alloy is termed a quinary
http://en.wikipedia.org/wiki/Metalhttp://en.wikipedia.org/wiki/Solid_solutionhttp://en.wikipedia.org/wiki/Chemical_elementhttp://en.wikipedia.org/wiki/Phase_(matter)http://en.wikipedia.org/wiki/Homogeneous_(chemistry)http://en.wikipedia.org/wiki/Solventhttp://en.wikipedia.org/wiki/Solventhttp://en.wikipedia.org/wiki/Solventhttp://en.wikipedia.org/wiki/Copper-nickelhttp://en.wikipedia.org/wiki/Copper-nickelhttp://en.wikipedia.org/wiki/Copper-nickelhttp://en.wikipedia.org/wiki/Copper-nickelhttp://en.wikipedia.org/wiki/Solventhttp://en.wikipedia.org/wiki/Homogeneous_(chemistry)http://en.wikipedia.org/wiki/Phase_(matter)http://en.wikipedia.org/wiki/Chemical_elementhttp://en.wikipedia.org/wiki/Solid_solutionhttp://en.wikipedia.org/wiki/Metal


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alloy. Because the percentage of each constituent can be varied,

with any mixture the entire range of possible variations is called

a system. In this respect, all of the various forms of an alloy

containing only two constituents, like iron and carbon, is called

a binary system,while all of the alloy combinations possible with

a ternary alloy, such as alloys of iron, carbon and chromium, is

called a ternary system.

The complete analysis of an alloy involves two steps,

qualitative and quantitative analysis. In qualitative analysis, the

components of the alloy are found out and in quantitative analysis

their percentage composition is determined.

The purpose of this project is to determine qualitatively, the

contents of samples of Brass and Bronze.


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Uses of Alloys

i To modify chemical reactivity:-

a. When sodium is used as reducing agent it is too

reactive to be used but its alloy with mercury, called

sodium amalgam can be safely used as reducing agent.

ii To increase hardness:-

b.Hardness of gold is increased by adding copper to it.

Also zinc is added to copper to make copper hard in

form of brass.

iii To increase tensile strength:-

c.

Nickeloy, an alloy of Nickel (1%), Copper (4%) and

aluminium (95%) has high tensile strength.

iv To lower the melting point:-


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d.Solder metal which is an alloy of Sn(30%) and

Pb(70%) has very less melting point as compared to

melting points of Sn and Pb.

v To modify the colour:-

e. Aluminium bronze an alloy of Cu and Al has a beautiful

golden colour.

vi To resist corrosion:-

f. Iron gets rusted and corroded. Its corrosion takes place

with time but for stainless steel, an alloy of iron (98%)

and carbon (2%) does not get rusted.


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Experiment 1

Aim:

To analyze a sample of brass qualitatively

Requirements:

China dish, test-tube funnel, filter paper and common laboratory

reagents.

Theory:

Brass is an alloy of copper and zinc with the following

Composition:

Cu = 60-90% and Zn. = 10-40%.

Thus Cu and Zn. form the main constituents of brass. Both these

metals dissolved in 50% of nitric acid due to formation of nitrates

which are soluble.

3Cu + 8HNO33Cu(NO3)2 + N2O + 5H2O


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Appearance of deep blue colouration in the solution shows the

presence of copper ions in the solution.

5. To test Zn2+ions, boil the filtrate to remove H2S gas, then add

solid NH4Cl to this and heat to dissolve NH4Cl. Add excess of

NH4OH so that a solution is ammoniacal. Now pass H2S gas

through this ammoniacal solution. Dirty white or grey

precipitation indicate zinc.

6. Separate the precipitates and dissolve it in minimum amount of

dil. HCl. Boil to expel H2S gas and add potassium Ferro cyanide

solution, white or bluish white ppt. confirm Zn2+ions in the

solution.

Result:

The given sample of brass contains copper and zinc metals as the

main constituents.


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Experiment 2

Aim:

To analyze a sample of bronze qualitatively

Requirements:

China dish, test-tube funnel, filter paper and common laboratory

reagents.

Theory:

Bronze is an alloy of copper and tin with the following.

Composition:

Cu = 88-96% and Sn. = 4-12%.

Thus copper and zinc form the main constituents of bronze. Both

these metals dissolved in nitric acid.

Cu + HNO3 Cu2+ + NO + H2O


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Sn + HNO3H2SnO3 + NO2 + H2O

(Conc. acid) (Metastannic Acid)

Excess of nitric acid is removed by heating the solution. The

resulting solution now would contain Cu2+ ions and metastannic

acid. This solution is acidified with dil. HCl and H2S gas is passed

when the sulphides of copper and tin are formed.

Cu2++ S2CuS (Black ppt.)

H2SnO3+ 2H2SSnS2(Black ppt.) + 3H2O

The sulphides are separated by boiling the ppt. with yellow

ammonium sulphide when SnS2 goes into solution as

thiostannate where as CuS is not affected.

SnS2+ (NH4)2S(NH4)2SnS2(Soluble)

Ammonium thiostannate.

CuS + (NH4)2SCuS (Unaffected)

Black ppt.


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The soluble black ppt. is tested for Cu2+ ions and the solution is

tested for Sn2+ions as in elementary qualitative analysis.

Procedure:

1. Take about 1g. of small pieces of bronze in a china dish and add

to it 5-10 ml. of dil. HNO3.

2. Heat the contents slowly to dissolve copper and tin completely

and then boil the contents to a paste to remove excess of HNO3.

All this is carried out in cup board.

3. Dissolve this dry mass in distilled water containing HCl (1:1) to

get a clear solution.

4. Transfer the solution in a test tube and pass H2S in excess i.e.

till the precipitation is complete. Filter and reject the filtrate.

5. Take the black ppt. in a test tube and add to it 2-3 ml. of yellow

ammonium sulphide and heat. Filter the contents. Black residue is

tested for Cu2+ions and filtrate is tested for Sn2+ions.

6. Analysis of black residue:


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Transfer a little of the black ppt. into a test tube. Add to it 2-3 ml.

of 50%. HNO3 and boil the contents of the tube. A light blue or

green sol. indicates the presence of Cu2+. Divide this sol. into two

parts.

(a) To one part add excess of NH4OH a deep blue colouration

confirms the presence of Cu2+ions.

(b) Acidify the second part with acetic acid and add K4 [Fe (CN)6]

i.e. potassium ferrocyanide solution. A reddish brown ppt.

confirms the presence of Cu2+ions.

7. Analysis of filtrate:

Boil the filtrate with 1 ml. of dil. HCl. A yellow ppt. is obtained.

Dissolve in 1 ml. conc. HCl. To this solution add 0.5 g. of zinc dust

and boil it for 2-3 minutes. Filter and to filtrate add 1-2 ml. of

mercuric chloride solution. A white ppt. turning grey on standing

confirms the presence of Sn4+ions.


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Result:

The given sample of bronze contains - Copper and Tin as the main

constituents.


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Conclusion

In this project, a qualitative analysis of two samples of alloys

namely, Brass and Bronze, was carried out to determine their

constituents. The given sample of bronze contains - Copper and

Tin as the main constituents and the given sample of bronze

contains - Copper and Tin as the main constituents.


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Bibliography

1.

Comprehensive Practical Chemistry by Lakshmi Publications2.NCERT Class 12 Chemistry


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chemistry investigatory project - study of constituent of alloys

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