Aim

To determine different metals present in different coins.

Requirements

Apparatus

1.Test Tubes 2.Beakers3.Funnel4.Filter Paper5.Burner6.China Dish7.Wire Gauze8.Tripod Stand 9.Test Tube Holder

Chemicals Required

1.Concentrated Nitric Acid2.Concentrated Hydrochloric Acid3.Dilute Hydrochloric Acid4.Hydrogen Sulphide5.Ammonium Hydroxide6.Ammonium Chloride7.Potassium Ferrocyanide8.Potassium Sulphocyanide9.DMG (Dimethyl Glyoxime)

Procedure

1.Prepare 100mL aqua regia by mixing 25mL concentrated nitric acid and 75mL concentrated hydrochloric acid.

2.Take 5mL of aqua regia in a china dish.3.Place the coin to be tested inside the china dish

carefully.4.Heat the china dish along with its contents.5.Wait for the metal in the coin to corrode in the

aqua regia.6.Take out the coin from the china dish and pour

the liquid left in the dish in a beaker.7.Use this liquid to test for the metals present in

the coin.8.Repeat the same procedure for different coins.

Observation Table

One Rupee Coin

Experiment Observation InferenceGroup ITo the original solution dil. HCl was added

No ppt. was formed Group I is absent

Group IITo the original solution dil. HCl was added and H2S gas was passed

No ppt. was formed Group II is absent

Group IIITo the original solution NH4Cland NH4OH were added

Confirmation:-The ppt. was filtered and HCl was added and then divided into parts.

1. K4[Fe(CN)6] was added to first part.

2. KSCN was added to second part.

Reddish brown ppt. was formed

Blue ppt. was formed

Blood red ppt. was formed

Fe3+ ions may be present

Fe3+ ions confirmed

Group IVTo the original solution NH4Cland NH4OH were added and H2S gas was passed

Confirmation:-The ppt. was dissolved in aqua regia and few drops of DMG and excess of NH4OH were added

Black ppt. was formed

Scarlet red ppt. was formed

Ni2+ ions may be present

Ni2+ ions confirmed

Two Rupee Coin

Experiment Observation InferenceGroup I

To the original solution dil. HCl was added

No ppt. was formed Group I is absent

Group IITo the original solution dil. HCl was added and H2S gas was passed

No ppt. was formed Group II is absent

Group IIITo the original solution NH4Cland NH4OH were added

Confirmation:-The ppt. was filtered and HCl was added and then divided into parts.

1. K4[Fe(CN)6] was added to first part.

2. KSCN was added to second part.

Reddish brown ppt. was formed

Blue ppt. was formed

Blood red ppt. was formed

Fe3+ ions may be present

Fe3+ ions confirmed

Group IVTo the original solution NH4Cland NH4OH were added and H2S gas was passed

Confirmation:-The ppt. was dissolved in aqua regia and few drops of DMG and excess of NH4OH were added

Black ppt. was formed

Scarlet red ppt. was formed

Ni2+ ions may be present

Ni2+ ions confirmed

Five Rupee Coin

Experiment Observation InferenceGroup I

To the original solution dil. HCl was added

No ppt. was formed Group I is absent

Group IITo the original solution dil. HCl was added and H2S gas was passed

Confirmation:-Ppt. was filtered and divided into two parts.

1. K4[Fe(CN)6] was added to first part.

2. KSCN was added to second part.

Black ppt. was formed

Chocolate brown colour appearedDeep blue colour appeared

Cu2+ ions may be present

Cu2+ ions confirmed

Group IIITo the original solution NH4Cland NH4OH were added

Confirmation:-The ppt. was filtered and HCl was added and then divided into parts.

1. K4[Fe(CN)6] was added to first part.

2. KSCN was added to second part.

Reddish brown ppt. was formed

Blue ppt. was formed

Blood red ppt. was formed

Fe3+ ions may be present

Fe3+ ions confirmed

Group IVTo the original solution NH4Cland NH4OH were added and H2S gas was passed

Confirmation:-The ppt. was dissolved in aqua regia and few drops of DMG and excess of NH4OH were added

Black ppt. was formed

Scarlet red ppt. was formed

Ni2+ ions may be present

Ni2+ ions confirmed

Result

1.One Rupee coin contains iron and nickel metals.2.Two Rupee coin contains iron and nickel metals.3.Five Rupee coin contains iron, nickel and copper

metals.

Precautions

1.All acids and aqua regia should be handled with care.

2.Chemicals should not be misused.3.Burner should be used carefully.4.Vapours rising from the heated solutions must

not be inhaled.

Chemical Reactions Involved

Cu2+ + 4NH4OH [Cu(NH3)4]2+ + 4H2O

Deep blue complex

2Cu2+ + K4[Fe(CN)6] Cu2[Fe(CN)6] + 4K+

Chocolate brown ppt.

4Fe3+ + 3K4[Fe(CN)6] Fe4[Fe(CN)6]3 + 12K+

Dark blue ppt.

Fe3+ + 3KSCN Fe(SCN)3 + 3K+

Blood red ppt.

DMG Scarlet red ppt.

Theory

MetalA metal (from Greek "μέταλλον" – métallon, "mine, quarry, metal") is a solid material (an element, compound, or alloy) that is typically hard, opaque, shiny, and features good electrical and thermal conductivity. Metals are generally malleable—that is, they can be hammered or pressed permanently out of shape without breaking or cracking—as well as fusible (able to be fused or melted) and ductile (able to be drawn out into a thin wire). 91 of the 118 elements in the periodic table are metals.

AlloyAn alloy is a mixture or solid solution composed of a metal and another element. An alloy will contain one or more of the three: a solid solution of the elements (a single phase); a mixture of metallic phases (two or more solutions); an intermetallic compound with no distinct boundary between the phases. Solid solution alloys give a single solid phase microstructure, while partial solutions give two or more phases that may or may not be homogeneous in distribution, depending on the thermal (heat treatment) history of the material. An intermetallic compound will have another alloy or pure metal embedded within another pure metal.

Alloys are used in some applications as their properties are superior to those of the pure component elements for those applications. Examples of alloys are solder, brass, pewter, phosphor bronze and amalgam.

Aqua RegiaAqua regia (Latin and Ancient Italian, lit. "regal water"), aqua regis (Latin, lit. "king's water"), or nitro-hydrochloric acid is a highly corrosive mixture ofacids, a fuming yellow or red solution. The mixture is formed by freshly mixing concentrated nitric acid and hydrochloric acid, optimally in a volume ratio of 1:3. It was named so because it can dissolve the so-called royal or noble metals, gold and platinum. However, titanium, iridium, ruthenium,tantalum, osmium, rhodium and a few other metals are capable of withstanding its corrosive properties.

Aqua regia is primarily used to produce chloroauric acid, the electrolyte in the Wohlwill process. This process is used for refining highest quality (99.999%) gold.

Aqua regia is also used in etching and in specific analytic procedures. It is also used in some laboratories to clean glassware of organic compoundsand metal particles. This method is preferred over the "traditional" chromic acid bath for cleaning NMR tubes, because no traces of paramagneticchromium can remain to spoil spectra.[3] While chromic acid baths are discouraged because of the high toxicity of chromium and the potential for explosions, aqua regia is itself very corrosive and has been implicated in several explosions due to mishandling.[4]

Due to the reaction between its components resulting in its decomposition, aqua regia quickly loses its effectiveness (yet remains a strong acid), so its components are usually only mixed immediately before use.

Acknowledgement

I gratefully acknowledge the valuable contributions of Ms. Madhu Mehta and Mr. Rajesh without whom this project would not have been materialized.

Bibliography

http://en.wikipedia.org/wiki/Metalhttp://en.wikipedia.org/wiki/Alloyhttp://en.wikipedia.org/wiki/Aqua_regia

Certificate

This is to certify that this project has been completed under my guidance and supervision by Tushar Garg, Class XII-A of Kulachi Hansraj Model School, Phase-III, Ashok Vihar, New Delhi, 110052.

Ms. Madhu Mehta

(Chemistry Dept.)