S.V.M PUBLIC SCHOOL

TOPIC- CONSTITUTENTS OF AN ALLOY

SUBMITTED TO- MR. DC SHARMA SUBMITTED BY- DEVA (CHEMISTRY H.O.D) SHARMA

CERTIFICATE

This is to certify that Deva sharma student of class 12th ‘A’,S.V.M Public School has successfully completed the research project on the topic “Study of constituents of ALLOYS” under the guidance of Mr. D.C Sharma during the academic year 2014-15 towards practical fulfillment of credit for the chemistry practical evaluation of AISSCE 2015 and submitted satisfactory report, as compiled in the following pages.

Teacher in charge: Mr. DC Sharma (chemistry H.O.D)

INDEX TOPICS PAGE NO.

1. Acknowledgement 1 2. Introduction 23. Aim of the experiment 3a- General objective b- Specific objective 4. Materials Required 45. Theory 5-76. Details of procedure 8-127. Conclusion 138. Bibliography 14

ACKNOWLEDGEMENT

I, Deva Sharma of class XLL –A express my gratitude to my school authorities for allowing me to undertake the project titled Alloy Analysis. I naturally could not have done justice to my delicate assignment, had I not been privileged to get the animate guidance from (Mr. D.C Sharma, Chemistry H.O.D SVM Public School) . I also express sincere thanks to my family who extended helping hand in completing this project.

I can’t forget to offer my sincere thanks to my classmates who helped me to carry out his project work successfully and for their valuable advice and support which I received from time to time.

INTRODUCTION

An alloy is a homogeneous mixture of two or more metals or a metal and non-metal.

They are generally harder than their components with reduced malleability and ductility. Alloys are prepared to enhance certain characteristics of the constituent metals, as per requirement.

In this project, we shall qualitatively analyze the chemical composition of two alloys: Brass and Bronze

AIM OF THE EXPERIMENT

* General objective: This project is being carried out with a view to increase the appreciation of alloy-analysis as an important branch of chemistry. The hands-on laboratory experience gained is highly beneficial in understanding the general procedure of qualitative analysis of an unknown sample. *Specific objective: In this project, we shall be analyzing the constituents of Brass and Bronze.

MATERIALS REQUIRED

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

THEORY

Brass :

Brass contains Cu and Zn . Both dissolve in nitric acid. 4Zn+ 10 HNO3= 4Zn(NO3)2 + N2O + 5H2O 3Cu + 8 HNO3= 3Cu(NO3)2 + 4H2O+2NO

Further analysis is carried out for respective ions. Cu dissolves in H2S to give black ppt. of CuS. It is filtered to get the soln of Zinc Sulphide. It precipitates out in the form of ZnCl2 in an ammoniacal soln. of Ammonium chloride. The precipitate is dissolved in dilute HCl and then treated with Potassium ferrocyanide to get a bluish-white ppt. of Zn2[Fe(CN)6].

Bronze :

Bronze contains Cu and Sn. Their nitrates are obtained by dissolving the sample in conc. Nitric acid. The nitrates are precipitated as sulphides by passing H2S through their solution in dil. HCl.

The CuS is insoluble in yellow ammonium sulphide, while SnS is soluble. The ppt. is separated by filtration.

The ppt. is dissolved in conc. HNO3 and then Ammonium hydroxide solution is passed through it.Blue colouration confirms the presense of Cu. The filtrate is treated with conc. HCl followed by Zinc dust to obtain SnCl2 . Then HgCl2 solution is added. Formation of slate-coloured ppt. indicates the presence of Sn.

SnS2 +HCl(conc.)= SnCl4 + H2S SnCl4 +Fe= SnCl2+FeCl2

SnCl2 + HgCl2 = Hg2Cl2 + SnCl4

USES OF ALLOYS

To modify chemical reactivity. To increase hardness. To increase tensile strength. To lower the melting point. To modify the color. To resist the corrosion.

EXPERIMENT-1

Objective : To analyse 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.

4Zn + 10HNO3 4Zn(NO3)2 +N2O + 5H20

3CU + 8 HNO3 3Cu(NO3)2 + 4 H20+ 2NO

PROCEDURE

1. Place a small piece of brass in a china dish and heat this with minimum quantity of 50% HNO3 so as to dissolve the piece completely.2. Continue heating the solution till a dry solid residue is obtained.3. Dissolve the solid residue in dil. HCl and filter. Add distilled water to the filtrate.4. Pass H2S gas through the filtrate. A black precipitate of copper sulphide isobtained. Separate the black ppt. and keep the filtrate for the test of Zn+2 ionsDissolve black ppt. by heating them with 50% HNO3. To this solution addammonium hydroxide solution. Appearance of deep blue coloration in the solutionshows the presence of copper ions in the solution.5. To test Zn+2 ions, boil the filtrate to remove H2S gas, then add solid NH4Cl to thisand 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 greyprecipitation indicate zinc. Separate the precipitates and dissolve it in minimumamount of dil. HCl. Boil to expel H2S gas and add potassium Ferro cyanide solution,white or bluish white ppt. confirm Zn+2 ions in the solution.

Result :The given sample of brass contains copper and zinc. metals as the mainconstituents.

EXPERIMENT-2Objective : To analyse 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 metalsdissolved in nitric acid.

3Cu + 8H+ + 2NO3 3Cu2+ + 2NO+ 4H20

4Sn + No3- + 10H+ 4Sn+2 + NH4+ + 3H2O(cold and dil acid)

Sn + 4NO3- + 4H+ H2SnO3 + 2NO2 + H2O

(conc. Acid) (Metastannic acid)

Cu2+ + s2 CuS(black ppt)

H2SnO3 + 2H2S SnS2(black ppt) + 3 H2O

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 Cu+2 ions and filtrate is tested for Sn+2ions

6. Analysis of black residue :

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 Cu+2. Divide this sol. into two parts.

(a) To one part add excess of NH4OH a deep blue coloration confirms the presence of Cu+2 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 Cu+2 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 Sn+4 ions.

Result :The given sample of bronze contains - Cu and Sn as the main constituents.

CONCLUSION

Brass contains Copper and Zinc.

Bronze contains Copper and Tin.

BIBLIOGRAPHY

www.google.com

www.cbse.nic.in Comprehensive 12th chemistry practical book.