CERTIFICATE This is certify that Ankur Singhal of class XII-B completed this project on TO ANALYSE THE METALS PRESENT IN INDIAN COINS
in the chemistry lab of D.L. D.A.V. Model School. His performance on the project was quite satisfactory
SIGN
ACKNOWLEDGEMENT
I would like to sincerely thank my chemistry teacher Mrs. Vibha mam for supporting me throughout the practical classes and helping me for completing this project without whose help I wouldn’t have come so far, also I would like to thank the lab assistant for also being there in the lab during experiments and helping me get acquainted with all the apparatus.
INDEX Introduction Apparatus Chemicals Theory Analysis Procedure Table 1 1,2,5 paisa Table 2 Rs 1, 2, 5 coins Conclusion Precaution Bibliography
INTRODUCTION Man was always been curious to know the nature of things around him. He has been continuously exploiting his surroundings in all possible ways to penetrate deep into the origin of all the things. He began with understanding the physical and chemical composition of various substances. These experiments led him to understand the nature in better way. Everybody in his or her daily life come across various types of coins. When we sell something we get coins and when we buy something we give coins. Leonardo-do Vinci once said “Experiments are the interpreter of nature” Experiments are the surest way to the confirmation of all processes. Here is an endeavour to satisfy that curious urge of enquiry. This project tries to analyse the various metals present in the coins used in many parts of India, which were used in ancient times as well as the once which are used in present times.
APPARATUS Test tubes Test tube stand Test tube holder Bunsen burner Beakers Petri dishes Filter paper Droppers Glass Roads Different Types Of Coins
CHEMICALS Dilute HCl Conc. HNO3 Conc HCl Dilute HNO3 Dilute H2SO4 Potassium Chromate PbCl2 NH4NO3 K4[Fe(CN)6] Solid AlCl3 COnc NH4Cl KCNS NaOH Fe(CN)6
THEORY Alloy: An alloy may be defined as a homogeneous mixture of two or more metals or a metal and a non-metal. Example Brass, Bronze, Stainless Steel. There are two general types of alloy. Inter-metallic compounds and interstitials
compounds of metals with a non-metal. Solid solution of meta and non – metals in metals.
SOME ADVANTAGES OF MAKING ALLOY ARE GIVEN BELOW.
S.No. ADVANTAGES EXAMPLES To increase Alloy of iron 1
2. 3. 4.
hardness with carbon To reduce corrosio Taking stainless teel from iron To reduce Brass, an alloy o sensitivity Cu is more tenacious To get better Antimony, added
casting
5. 6.
to lead to make type metal To lower melting Soldier, an alloy boiling point of lead iron To modify chemica Amalgams are activity made for this purpose
ANALYSIS The analysis of elements in Indian coins is based upon the salt analysis scheme of the basic radicals confirmatory tests of elements involved are as follows: We can determine the constituent of an unknown alloy by dissolving it in some simple acid or aquaregia and the solution, thus obtained can be subjected to usual qualitative analysis to determine the constituent.
2+
LEAD (Pb ): To test for “lead” first of all add dil. HCl to original solution and lead is precipitated as PbCl2 Pb2+ + 2ClPbCl2 (White) The solution of lead chloride given a yellow precipitate of lead iodine with potassium iodide solution and of lead chromate with potassium chromate solution. PbCl2 + 2KI
PbCl2+K2CrO4
PbI2 + 2KCl (Yellow ppt.)
PbCrO4 + 2KCl (Yellow ppt.)
2+
COPPER (Cu ): Copper belongs to the second group and gives black ppt. of CuS when H2S is passed through original solution plus dil. HCL. CuS+ 2H+ (Black ppt.)
Cu + H2S
Black precipitate of copper sulphide dissolves in 50% HNO3 acid forming a green solution of copper nitrate. 3Cu+8HNO3
3Cu(NO3)2 + 2NO + 4H 2O (Green Solution)
CONFIRMATORY TEST
Cu(OH)2 + 2NH4NO3 + 2NH4OH Cu(NH3)4(NO3)2 + 4H2O
(Deep blue)Cu(NO 3)2+ 2NH4OH Cu(OH)2+2NH4NO3 (Black ppt.) If NaOH is added in excess: Cu(OH)2 + 2NH4NO3 + 2NH4OH Cu(NH3)4(NO3)2 + 4H2O (Deep blue)
2CuSO4+K4(FeCN6)+2K2SO4
3+
ALUMINIUM (Al ):
Aluminium gives white ppt. of Al(OH)3 in the IIIrd group. When NH 4 along with NH4CL is added 3Al+3NH4OH
Al(OH)3+3NH4 (White gelatinous ppt.)
Filter and dissolve the ppt. in a little dil. HCL and a drop of blue litmus paper solution and add to it dil.NH4OH drop wise. A blue lake is formed. In case, Al (OH)3 absorbs all the colouring matter of the litmus forming a complex compound called blue lake.
3+
IRON(Fe ):
Iron gives reddish brown ppt. in the
IIIrd group test. Fe3+ + NH4OH
Fe(OH)3+3NH4 (Brown ppt.)
The ppt. of Fe(OH)3is soluble in dil. HCL giving FeCL3
CONFIRMATORY TEST 4FeCl3 + 3K4[Fe(CN)6]
4 FeCL3 + 6KCNS (Pot.Sulphocyanide)
Fe4[Fe(CN)6] + 12KCl (Ferric Frrrocyanide) K3Fe(CNS)6 + 3KCl. (Pot.Feric Sulphosyanide)
2+
ZINC(Zn ):
If Zn2+ is present then on passing H 2S through the IIIrd group white precipitate is formed. Zn2+ + H2S (White ppt.)
ZnS + 2H+
Dissolve the ppt. in dil. HCL and boil of H2S ZnS + 2HCL (i)ZnCL2 + 2NaOH
ZnCL2 + H2S Zn(OH) 2 + 2NaCl (White ppt.)
If NaOH is added in excess: Zn(OH) 2+2NaOH Zn(ONa)2+2H2O
(Sod. Zincate) (ii) 2ZnCL2 + K4Fe(CN)6 Zn2Fe(CN6)+4KCl (Zinc. Ferro cyanide) 2+ MAGNESIUM (Mg ): To the solution add NH 4OH and (NH4)3 PO4 i.e. Ammonium phosphate in excess. White ppt. of Mg NH4CL is formed. Mg(NO3)2 + Na2HPO4 + NH4OH Mg NH4PO4+2NaNO3+H2O
PROCEDURE PREPARATION OF AQUAREGIA: Took a clear
beaker and put three test tubes of conc. HCL in it. To this add one test tube of concHNO3 stir it. Thus, form mixture of aquaregia. TAKE THE SMALL BEAKERS: And paste a white blank slip on these. Put equal amount of aquaregia in all the beakers and label them according to the coins to be put into them. CLEAN THE COINS: So that no dust is left on them and dry them. Put them in beakers label for them. Place three beakers in some safe place and remain them for two to three days. After two days, COINS WERE DISSOLVED and there was solution in the beakers. Add half beaker of water in each solution. Detect the basic radicals step by step in each coin. Tables are given below showing the observations and result of qualitative analysis..
TABLE 1
For coins of 1, 2, 5 paisa.. S.N EXPERIMENT o 1. Observe the colour of the coin 2. Dissolve them in aquaregia 3. To the O.S. add dil. HCL 4. To the above sol pass H2S 5. To the OS add NH4Cl and boil, and then add NH4OH in excess. 6. i)
Confirmatory test: Dissolve the above ppt. in HCl. To this add blue litmus and then add NH4OH drop wise.
OBSERVA TION Silvery white Gas evolved No ppt of HCL No precipitate White precipitate formed.
Blue lake.
INFERENCE Al3+, Zn may be present NO2 may be present. Group 1st is absent. Group 2nd is absent Group 3rd may be present.
Al3+ confirmed.
7. 8.
9.
i)
ii)
To a part of O.S. add No colour. KCNS. To the 3rd group Black ppt filtrate added H2S. If formed. ppt forms pass H2S through the whole solution.
Fe3+ absent.
Dissolve the black ppt in aquaregia. Evaporate to dryness. Confirmatory Test: Yellow residue+ distilled water.divide in two parts. Part 1+NH4OH+ a few drops of dimethylglyoxime(D MG) Part 2+NaOH solution water and boil Reduce the group 4 filtrate to its 1/3rd by boiling +NH4OH take a portion and add (NH4OH)2CO3 solution+ warm and allow to stand
Ni2+ may be present.
Yellow residue.
Group 4 present.
Green colour solution Bright Rose Ni2+ red ppt confirmed formed Black ppt forms
Ni2+ confirmed
No ppt formed
Group 5 absent.
TABLE 2 For coins of Rs 5, Rs2 and Rs1.. S.N EXPERIMENT o 1. Observe the colour of the coin 2. Dissolve them in aquaregia 3. To the O.S. add dil. HCL 4. To the above solution pass H2S 5.
i)
ii)
6.
Wash the ppt with water + 50% HNO 3 and boil. CONFIRMATORY: Divide the solution in three parts. Part 1 + excess of NH3. Part 2 + Acetic acid + potassium Ferrocynaide To the OS add NH4Cl and boil, and then add
OBSERVA TION Silvery white Gas evolved No ppt. Black precipitate formed Bluish green
INFERENCE Al3+, Zn may be present NO2 may be present. Group 1st is absent. Group 2nd is present Cu2+ may be present.
Blue colour Cu2+ confirmed Chocolate brown ppt
Cu2+ confirmed
Reddish brown
Group 3rd may be
NH4OH in excess. 6.
i)
ii)
8.
9.
precipitate formed.
Confirmatory test: Ppt + dil HCl dissolve and divide in 2 portions Portion 1+ pot Prussian ferrocynaide solution blue colouration. Portion 2+ pot. Blood red sulphocyanide colouration solution To the 3rd group Black ppt filtrate added H2S. If formed. ppt forms pass H2S through the whole solution. Dissolve the black Yellow ppt in aquaregia. residue. Evaporate to dryness. Confirmatory Test: Yellow residue+ distilled water. Divide in two parts. Part 1+NH4OH+ a few drops of dimethylglyoxime(D MG) Part 2+NaOH
present.
Fe3+ confirmed. Fe3+ confirmed. Group 4 present.
Ni2+ may be present.
Green colour solution Bright Rose Ni2+ red ppt confirmed formed Black ppt
Ni2+
solution water and boil
forms
confirmed
CONCLUSION 1) The one to five paisa coins contain: Al3+, Ni2+ ions. 2) The coins of Rs 1, Rs 2, Rs 5 contain: Cu2+, Fe3+, Ni2+ ions.
PRECAUTION i) Handle the apparatus carefully. ii) The solution of aquaregia prepared should be handled carefully. iii) The colour of the solution made after test should be observed carefully. iv) The chemicals should be put accurately in the test tubes.
BIBLOGRAPHY www.google.com www.rbi.org.in/currency/museum/c-rep.html
