chemistry project class xii

8/14/2019 CHEMISTRY PROJECT class XII

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CHEMISTRY PROJECT

PREPARATION OF POTASH

ALUM FROM SCRAP

ALUMINIUM

KAPIL KUMAR

XIITH C3

ROLL NO. -123123132

GREENFIELDS PUBLIC SCHOOL


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CERTIFICATE

It is to hereby certify that, the original and genuine

research work is carried out to investigate aboutthe subject matter and the related data collection

has been completed solemnly and satisfactorily by

Kapil Kumar of class XII C3 regarding the project

Preparation of Potash Alum from Scrap

Aluminium

Signature

(Mrs. Rekha Chopra)


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ACKNOWLEDGEMENTS

I would like to thank my chemistry teacher Mrs. Rekha

Chopra for her guidance and support. I also like tothank my Principal Mrs. M. Barsaley. I would also like

to thank my parents and my classmate for encouraging

me during the course of this project.

Kapil Kumar


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Introduction

Aluminium because of its low density, high tensile

strength and resistance to corrosion is widely used for

the manufacture of aeroplanes, automobiles, lawn

furniture as well as for aluminium cans. Being good

conductor of electricity it is used for transmission of

electricity. Aluminium is also used for making utensils.

The recycling of aluminium cans and other aluminium

products is a very positive contribution to saving our

natural resources. Most of the recycled aluminium is

melted and recast into other aluminium metal

products or used in the production of various

aluminium compounds, the most common of which arethe alums.

Alums are double sulphates having general formula:-

X2SO4.M2(SO4)3.24H2O


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Some important alums and their names are given

below:

K2SO4.Al2(SO4)3.24H2O- Potash Alum

Na2SO4.Al2(SO4)3.24H2O- Soda Alum

K2SO4.Cr2(SO4)3.24H2O- Chrome Alum

(NH)2SO4.Fe2(SO4)3.24H2O- Ferric Alum

Potash alumis used in papermaking, in fire

extinguishers, in food stuffs and in purification of

water.

Soda alumused in baking powders and chrome alumis

used in tanning leather and water proofing fabrics.


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In addition to these primary uses, alum is also used as

i) An astringent. A substance or preparation, thatdraws together or constricts body tissues and iseffective in stopping the flow of blood or other

secretions. Alum has also been used by

conventional hairdressers for treating shaving

cuts.

ii) A mordant. Substances used in dyeing to fixcertain dyes on cloth. Either the mordant or a

colloid produced by the mordant adheres to thefiber, attracting and fixing the colloidal mordant

dye. The insoluble, colored precipitate that is

formed is called a lake. Alum is a basic mordant

used for fixing acid dyes.

iii) For the removal of phosphate from natural andwaste waters.The aluminium ions of alum

combine with the orthophosphate around pH 6

to form the solid aluminium hydroxyphosphate

which is precipitated.

iv) For fireproofing fabrics.


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Aim

To prepare potash alum from

aluminium scrap.


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Apparatus

250 ml flaskFunnelBeakerScrap aluminium or cola canPotassium hydroxide solution(KOH)6 M Sulphuric Acid (H2SO4)Water BathEthanol


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Theory

Aluminum metal is treated with hot aqueous KOH

solution. Aluminium dissolves as potassium aluminate,

KAl(OH)4, salt.

Potassium aluminate solution on treatment with dil.Sulphuric acid first gives precipitate Al(OH)3, which

dissolves on addition of small excess of H2SO4and

heating.

The resulting solution is concentrated to near

saturation and cooled. On cooling crystals of potash

alum crystallize out.


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Reactions


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Procedure

Clean a small piece of scrap aluminium with steelwool and cut it into very small pieces. Aluminium

foil may be taken instead of scrap aluminium.

Put the small pieces of scrap aluminium oraluminium foil (about 1.00g) into a conical flask andadd about 50 ml of 4 M KOH solution to dissolve

the aluminium.

The flask may be heated gently in order tofacilitate dissolution. Since during this step hydrogen

gas is evolved this step must be done in a well

ventilated area.

Continue heating until all of the aluminium reacts. Filter the solution to remove any insoluble

impurities and reduce the volume to about 25 ml by

heating. Allow the filtrate to cool. Now add slowly 6 M

H2SO4until insoluble Al(OH)3just forms in the

solution.


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Gently heat the mixture until the Al(OH)3precipitate dissolves.

Cool the resulting solution in an ice-bath for about30 minutes whereby alum crystals should separateout. For better results the solution may be left

overnight for crystallization to continue.

In case crystals do not form the solution may befurther concentrated and cooled again.

Filter the crystals from the solution using vacuumpump, wash the crystals with 50/50 ethanol-water

mixture.

Continue applying the vacuum until the crystalsappear dry.

Determine the mass of alum crystals.


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Observations

Mass of aluminium metal = __________g

Mass of potash alum = __________g

Theoretical yield of potash alum = __________g

Percent yield = __________%


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Result

Potash alum was prepared fromaluminium scrap.


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Bibliography

www.cbseportal.comWikipedia

Chemicalland.com

books.google.co.in

chemistry project class xii

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