A Chemistry Project

on

Study of

Constituents of

Alloy

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AIM GENERAL OBJECTIVE: This project was carried out to gain knowledge regarding

alloys, their constituents and uses. The projects mainly

stressed on analyzing the alloys for their constituents and

appreciate the chemistry behind it.

SPECIFIC OBJECTIVE:

In this project the alloys, bronze and brass have been

qualitatively analyzed in order to find out their constituents.

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Contents 1. Certificate …1

2. Aim …2

3. Introduction …4

4. Apparatus …9

5. Theory …10

6. Procedure …11

7. Observations …13

8. Declaration …14

9. Bibliography …15

Actually acknowledgement page

must be on the beginning page of the

project before the Aim..

Sorry for the mistake…

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Introduction

Pure metals possess few important physical and

metallic properties such as melting point, boiling

point, density, specific gravity, high malleability,

ductility, and heat and electrical conductivity. For

many human needs

the extents of these

properties possessed

by these pure metals

don’t become much

beneficial.

Therefore to change

(or improve) the

properties, often

these metals are

combined with other metals or non-metals. This

process of mixing a metal with other metals or a

non-metal is called alloying and the resultant solid

solution obtained in the process is termed as an

Alloy. The constituent elements are combined in

Molten bronze being casted

into coin molds.

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such a way that they cannot be separated merely by

physical means. More than 90% of the metals used

are in the form of alloys.

A List of Alloys, their constituents and uses.

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Alloys are generally made to:

Enhance the hardness of a metal: An alloy is

generally harder than its constituents. The pure

metals are generally soft.

Lower the melting point: Pure metals have a

high melting point. The melting point lowers

when pure metals are alloyed with other metals

or nonmetals. This makes the metals easily

fusible.

Enhance tensile strength: Alloy formation

increases the tensile strength of the parent metal.

Enhance corrosion and/or heat resistance: Alloys

are more resistant to corrosion than pure metals.

Metals in pure form are chemically reactive and

can be easily corroded by the surrounding

atmospheric gases and moisture. Alloying a

metal increases the inertness of the metal, which,

in turn, increases corrosion resistance.

Modify color: The color of pure metal can be

modified by alloying it with other metals or

nonmetals containing suitable color pigments.

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Obtain superconductivity: Some metals can be

alloyed in such a way that their alloy behaves as

a superconductor which is of high importance in

technological advancement.

Provide better castability: One of the most

essential requirements of getting good castings

is the expansion of the metal on solidification.

Pure molten metals undergo contraction on

solidification. Metals need to be alloyed to

obtain good castings because alloys expand...

Few examples of alloys are stainless steel, brass,

bronze, nichrome, constantan, crown gold, solder,

amalgam etc…which are used in soldering, super

conduction making utensils, mechanical materials

like screws and blots etc…

A coin made of Bronze

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In this project, the chemical

compositions of two alloys

namely, brass and bronze

have been quantitatively

analyzed.

A few other materials made

of alloys

A screw made of Brass An Alloy wheel frame

Toy of an Alloy, Zamak A superconductor Alloy

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Apparatus

1. Brass and Bronze pieces 2. China dishes 3. Filtration apparatus 4. Nitric acid 5. Hydrogen sulphide gas 6. Ammonium chloride 7. Ammonium sulphide 8. Dil. hydrochloric acid 9. Mercuric chloride

10. Potassium Ferro cyanide

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Theory

Brass:

Brass is an alloy constituting Cu and Zn. Both the

ions dissolve in 50% of nitric acid due

to the formation of nitrates which are soluble.

4Zn + 10HNO3 → 4Zn(NO3)2 + N2O + 5H2S

3Cu + 8HNO3

→ 3Cu(NO3)2 + 4H2O + 2NO

A small piece of brass is dissolved in 50% nitric

acid. After the removal of excess of nitric acid, the

solution is tested for Cu2+ and Zn2+ ions.

Bronze:

Bronze contains Cu and Sn. Their nitrates are

obtained by dissolving the sample in conc.

nitricacid. The nitrates are precipitated as a sulphide

by passing H2S through their solution in dil. HCl.

CuS is insoluble in yellow ammonium sulphide,

while SnS is soluble. The ppt. is separated by

filtration. The ppt. is dissolved in conc. HNO3

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and then Ammonium hydroxide solution is passed

through it. Blue coloration confirms the presence of

Cu.

The filtrate is treated with conc. HCl followed by

Zinc dust to obtain SnCl2.

Then HgCl2solution is added. Formation of slate-

coloured ppt. indicates the presence of Sn.

Procedure

For Brass:

1. A small piece of brass was taken in a china dish

and was heated with a small quantity of 50% HNO3

so as to dissolve the piece completely.

2. The solution was heated till a solid residue was

obtained.

3. The solid residue was dissolved in dil.HCl and

filtered. Distilled water was later added to the

filtrate.

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4. H2S gas was passed through the filtrate. A black

precipitate of CuSO4 was obtained. The black ppt.

was separated and the filtrate was kept for testing the

presence of Zn2+ ions. The black ppt. was dissolved

by heating it with 50% HNO3. To this solution,

ammonium hydroxide solution was added. A deep

blue color appeared in the solution which showed

the presence of copper ions in the solution.

5. To test for the presence of Zn2+ ions: The filtrate

was boiled to remove H2S gas. Then NH4Cl was

dissolved in this filtrate by heating. To make the

solution ammonical excess NH4OH was added. Then

H2S gas was passed through this ammonical

solution. A dirty white or grey ppt. was formed. The

ppt. was then dissolved in minimum amount of dil.

HCl. The solution was boiled to expel any H2S gas

and Potassium ferrocyanide solution was added.

Bluish white ppt. was formed which confirmed the

presence of Zn2+ ions in the solution.

For Bronze

1. The sample was dissolved in 50% HNO3 and then

heated to obtain nitrates.

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2. The nitrates were dissolved in dil. HCl and then

precipitated as sulphides by passing H2S gas.

3. The precipitates were treated with yellow

ammonium sulphide when a part of it dissolves. The

soln. was filtered.

4. The ppt. was tested for Cu as in the case of brass.

5. The filtrate was treated with conc. HCl followed

by Fe dust.

6. Then HgCl2 soln. was added. Formation of a

slate-colored ppt. confirmed the presence of

Sn.

Observations

The following were found to be the constituents of

the alloys which were experimentally analyzed.

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Alloy Constituents

Brass Zinc, Copper

Bronze Tin, Copper

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Declaration I hereby declare that the project entitled “Study of

Constituents of an Alloy” submitted to XYZ222

School, Bengaluru, is a record of an original work

done by me by gaining the knowledge related to the

project from certain resources.

- M.S.Somanna

Student, Class 12,

XYZ222 Central School,

Bengaluru.

Bibliography

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List of alloys. - Wikipedia.org

en.wikipedia.org/wiki/List_of_alloys

Alloys and their purposes. - Globalspec.com

www.globalspec.com/reference/46877/203279/purpose-of-making-alloys

NCERT Chemistry - Class 12.

Comprehensive Class 12 Chemistry Practicals.

Alloys And their properties – gcsescience.com www.gcsescience.com/ex29.htm

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ACCKNOWLEDGEMENT

I hereby like to express my

gratitude to my school authorities

for suggesting and encouraging

me to undertake the project

entitled “Study the constituents of an alloy”.

I would also express my special

thanks to the members of the

school chemistry dept. for supporting me.

-M.S.Somanna

Class XII

Actually acknowledgement must be

on the beginning page of the project.

Sorry for the mistake…

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