Answer to Question #258904 in General Chemistry for Ayerhs

Question

Investigatory project on Constitutes of Alloys.

With images

Answer 1

HEADING:- INVESTAGATORY PROJECT ON CONSTITUTENTS OF ALLOY

#CONTENTS:-

1- INTRODUCTION

2-SOME COMMON ALLOY

3-PREPRATION OF AN ALLOY

4-ANALYSIS OF AN ALLOY

5-USES OF AN ALLOY

6-EXPERIMENT BRASS

1-INTRODUCTION:-

An alloy is a homogenous mixture of two or more metals or a non-metal. The term alloy is used to describe a mixture of atoms in which the primary constituent is a metal. The primary metal is called a base matrix or the solvent. The secondary constituents are often called solutes. If there is a mixture of only two types of atoms, not counting impurities, such as copper nickel then it is called a binary alloy. If there are three types of atoms forming the mixture such as iron, nickel, and chromium then is called a ternary alloy. an alloy with four constituents is called a quaternary alloy while an alloy with five constituents is termed as quinary alloy.

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 point of the constituents metals. Other properties such as reactivity towards atmospheric oxygen and moisture , mechanical strength, ductility, color e.t.c also undergoes a change when an alloy is made from its constituents. This change of properties is very useful and makes an alloy beneficial.

#SOME OF THE ALLOYS ALONG WITH THIER COMPOSTION IS GIVEN BELOW:-

1-BRASS- It consists copper 50 to 90%

zinc 20 to 40 %

and small amount of tin, lead and iron

2-BRONZE- It consists copper 60 to 90%

tin 5 to 35%

and also contain small amount of lead, iron, and zinc

3-GUN METAL- It consists of copper 85 to 90%

2-SOME COMMON ALLOYS:-

[A] Amalgam:- An alloy of mercury is called an amalgam. Most metals are soluble in mercury, but some (such as an iron) are not. Amalgam are commonly used in dental fillings because they have been relatively cheap, easy to use, and durable. In addition thallium amalgam is used as the liquid material in thermometers, because it freezes at -58 degree Celsius whereas pure mercury freezes at -38 degree Celsius.

[B]Brass:- A decorative brass paper weight along with zinc and copper samples.

Brass is the term used for alloy of copper and zinc in a solid solution. It has yellow color. Brass is relatively resistant to tarnishing and is often used for decorative purposes. Its malleability and acoustic properties have made in the metal of choice for musical instruments such as the tuba, trumpet, and euphonium.

[C]Bronze:- Bronze refers to a broad range of copper alloys usually with tin as the main additive, but sometimes with other element such as phosphorous, manganese, aluminum, or silicon. Basically bronze is about 60% copper and 40% tin. Bronze was used in building material for decorative purposes and tools and weapons. Bronze is less brittle than iron and has a lower casting temperature . Several bronze alloy resist corrosion and metal fatigue better than steel they also conduct heat and electricity better than most steels.

3-PREPRATION OF AN ALLOYS:-

Alloys are prepared from the techniques of fusion, compression or simultaneous electrodeposition. 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.

4-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 alloy. It involves the separation of the components from the alloy quantitatively followed by determination of percentage of each component volumetrically.

5-USES OF AN ALLOY:-

a- To modify chemical reactivity:- When sodium is used as reducing agent it is too reactive to be used but its alloy with mercury called sodium amalgam can be safely used as reducing agent.

b-To increase hardness:- Hardness of gold is increased by adding copper to it. Also zinc is added to copper to make copper hard in form of brass.

c- To increase tensile strength:- Nickeloy an alloy of nickel 1%, copper 4% and aluminium 95% has high tensile strength.

d-To lower the melting point:- Solder metal is which is an alloy of Sn 30% and Pb70% has very less melting point as compared to melting point of Sn and Pb.

e-To resist corrosion:-Iron gets rusted and corroded. Its corrosion takes place with time but stainless steel, an alloy of iron and carbon gets not rusted the composition of stainless steel is iron 98% and carbon 2%

6-EXPERIMENT OF BRASS:-

Aim- To analyze a 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 metal dissolved in 50% of nitric acid due to formation of nitrates which are soluble.

3Cu + 8HNO₃ (DIL.)3Cu (NO₃)2 + 2NO + 4H₂O

The solution is boiled to expel the oxides of nitrogen and the resulting solution is tested for Cu2+ and Zn+2 ions

PROCEDURE:-

1-Place a small pieces 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 dry solid residue is obtained.

3-Dissolove 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 solution coloration in the solution shows the percentage of copper ions in the solution.

5-To test Zn+2 ions boil the filtrate to remove H2S gas then ass solid NH4Cl to this and heat to dissolve NH4Cl. add excess oh NH4OH so that a solution is ammoniacal 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 blueish white ppt. confirm Zn+2ions in the solution.

RESULT:-The given sample of brass contains copper and zinc metals as the main constituents.