CheM IstRY ProJeCt
Submitted By:TARUNMALHOTRAClass : XII- C3
AcknowledgementI wish to express my deepgratitude and sincere thanks to the Principal, Dr M.Barsaley, Greenfields Public school for her encouragement and for all the facilities that she provided for this project work. I sincerely appreciate this magnanimity by taking me into her fold for which I shall remain indebted to her. I extend my hearty thanks to Mrs.Alka Tyagi, Chemistry teacher ,who guided me to the successful completion of this project. I take this opportunity to express my deep sense of gratitude for her invaluable guidance, constant encouragement , immense motivation , which has sustained my efforts at all the stages of thisproject workI cant forgot to offer my sincere thanks to parents and also to my classmates who helprd me to carry out this project work successful and for their valuable advice and support , which I received from them time to time.
-: Certificate :- Guided By :- Mrs. Alka Tyagi Class :- XII C3 Year :- 2011- 2012 Roll No :- ________________ School :- Greenfields Public School Certified to be the bona fide work done by-
Master ______________ of class XII-C3 in theChemistry Lab during the year 2011-2012.Date :-________Submitted for Central Board of Secondary Education.Examination held in Chemistry lab at GreenfieldsPublic School. EXAMINER
-: INDEX :- 1-- Introduction 2-- Some Common Alloys
3-- Preparation of alloys
4-- Analysis of an alloy
5-- Experiment 1 to analyze a sample of brass qualitative
6-- Experiment 2 to analyze a sample of bronze qualitatively
7-- Uses of Alloy
An Alloy is a homogenous mixture of two or more metals or a non-metal.An alloy of mercury with another metal is called amalgam.Alloys are usually harder than their components but very often less ductile and less malleable. Thus the hardness of gold is increased by addition of copper to it. The melting point of an alloy is always lower than the melting points of the constituent metals. Other properties such as reactivity towards atmospheric oxygen and moisture, mechanical strength, ductility, colour etc. also under goes a change when an alloy is made from its constituents (metals). This change of properties is very useful and makes an alloy beneficial.Some of the alloys along with their composition is given below.1. Brass :- It consists copper-50-90%. Zinc. : 20-40% and small amounts of tin, lead and iron.2. Bronze : It consists copper 60-90%.3. Tin : 5-35% and also contains small amounts of lead, iron and zinc. Duralumin : It consists A1 : 95%, Cu = 4% Mn = 0.5%, Mg = 0.5%4. Gun Metal : It consists copper 85 - 90%5. Zinc. : 1-3%6. Tin : 8-12% The composition of alloys may differ slightly depending upon the quality of the alloy though the main components remain the same.
Any alloy of mercuryis calledanamalgam.Most metals aresoluble in mercury,but some (suchasiron)are not. Amalgams arecommonly usedin dentalfillings because theyhave been relativelycheap, easy to use,and durable.In addition, until recently,theyhave been regardedassafe.Theyare made by mixing mercurywith silver ,copper ,tin , and othermetals. The mercury content ofdentalfillings hasrecently stirredcontroversy,basedon thepotentially harmful effects of mercury.
Mercury amalgams have also been usedin the process of mininggoldand silver, because of the ease with whichmercuryamalgamateswith them. In addition , thalliumamalgamis usedas the liquid materialin thermometers, because it freezesat-58C,whereas pure mercury freezesat -38C.
A decorative brass paperweight (left), along with zinc and coppersamples.Brassis the term usedfor alloysof copper and zincin a solidsolution. It hasa yellow color, somewhatsimilartogold. It wasproduced in prehistoric times, long before zinc wasdiscovered, bymelting copperwith calamine,a zinc ore.The amount of zinc in brass variesfrom 5 to 45 percent, creatinga range of brasses, eachwith unique properties. By comparison,bronzeis principally analloy of copperandtin.
Some Common Alloys :-
Despite this distinction, some typesof brassesare calledbronzes.Brass is relatively resistant to tarnishing and is oftenusedfordecorative purposes. Its malleability and acoustic propertieshavemade it the metalof choiceformusical instrumentssuchasthe
trombone,tuba, trumpet, and euphonium. AlthoughsaxophonesAnd harmonicasare made out of brass, the saxophone is awoodwind instrument, and the harmonica, a freereed aero phone.In organpipesdesignedas"reed" pipes, brass strips are usedasthe "reed."
Aluminummakesbrass strongerand more corrosion-resistant. Itforms a transparent, self-healing, protective layerof aluminumoxide (Al2O3) on the surface.Tin hasa similareffect and finds itsuse especially in seawaterapplications (navalbrasses).Combinations of iron, aluminum, silicon, and manganesemake brassresistant to wear and tear.
Bronzerefers to a broadrange of copper alloys, usually with tinasthe main additive,but sometimeswith otherelement ssuchasphosphorus,manganese,aluminum, or silicon. Typically,bronze isabout 60 percent copperand 40 percent tin. The use of bronze wasparticularly significant for early civilizations, leading to the name "Bronze Age." Tools, weapons,armor, and building materials suchasdecorative tileswere madeof bronze,as theywere found to be harderand more durablethantheir stone and copperpredecessors.
In early use,the naturalimpurity arsenicsometimescreateda superior naturalalloy,called"arsenical bronze."
Though not asstrong assteel, bronze is superior to ironin nearlyevery application. Bronze develops a patina (a green coating onthe exposedsurface), but it doesnot oxidize beyond the surface.It is considerably less brittle thaniron and hasa lowercastingtemperature.Severalbronze alloysresist corrosion(especially byseawater) and metalfatigue betterthansteel; theyalso conduct
Heat andelectricitybetterthanmost steels.Bronze hasmyriadusesin industry.It is widely usedtodayforsprings, bearings, bushings, and similarfittings, and is particularlycommon in the bearings of small electric motors. It is also widelyusedfor cast metalsculptureand is the most popularmetalfortop-quality bells and cymbals.
Commercialbronze,otherwise known asbrass, is 90 percentcopperand 10 percent zinc.It contains no tin
Preparation of Alloys
Alloys are prepared from the techniques of fusion, compression or simultaneous electro - deposition. Generally the components are mixed together in proper properties in a fuse clay crucible, melted and stirred with a piece of charcoal to avoid oxidation. The molten mixture is now allowed to cool. When an alloy is obtained e.g. brass is prepared by above melted. Analysis of an alloy
The complete analysis of an alloy involves two steps.1. Qualitative Analysis :This involves identification of the components of the alloys.
2. Quantitative Analysis :This involves determination of the components of the alloy. It involves the separation of the components from the alloy quantitatively followed by determination of percentage of each component volumetrically or gravimetrically.In this project we will carry out qualitative analysis only.Objectives of Project :In this project, our aim is to know the various metals present in the given sample of alloy.
To analyze a sample of brass
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.3 Cu + 8HNO3(Dil) 3 Cu (NO3)2 + 2NO + 4H2O orCu + 8H+ + 2NO3 3 Cu+2 + 2NO + 4H2O4Zn + 10HNO3(Dil) 4 Zn (NO2)2 + N2O + 5H2O4Zn + 2NO3 + 10H+ 4 Zn+2 + N2O + 5H2OThe solution is boiled to expel the oxides of nitrogen and the resulting solution is tested for Cu2+ and Zn+2ions.Procedure :1. Place a small piece of brass in a china dish and heat this with minimum quantity of 50% HNO3so 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 is obtained. Separate the black ppt. and keep the filtrate for the test of Zn+2 ions Dissolve black ppt. by heating them with 50% HNO3. To this solution add ammonium hydroxide solution. Appearance of deep blue coloration in the solution shows 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 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. 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 Zn+2ions in the solution.
Result :The given sample of brass contains copper and zinc. metals as the main constituents.
Aim : To analyze a sample of brass qualitatively.
To analyze a sample of bronze
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% an