chemistry project on preparation of potash alum

PREPARATIOIN OF POTASH ALUM

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A PROJECT REPORT SUBMITTED TOCHEMISTRY DEPARTMENT

DIST: AMRELIGUJARAT

BY:-ANURAG AGARWALROLL NO:XII SCI.

2009-2010PRINCIPAL INTERNALEXAMINER

EXTERNAL EXAMINER

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CERTIFICATECertificate

This is to certify that this project work issubmitted by ANURAG AGARWAL to theChemistry department, Aditya Birla PublicSchool, Kovaya was carried out by him underthe guidance & supervision during academicyear 2008-2009.

Principal TeacherMrs. Raji Jayaprasad Mr. B.D.KOTWANIAditya Birla public School (Head of chemistry dept.)Kovaya

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ACKNOWLEDGEMENTAcknowledgement

I wish to express my deep gratitude and sincere thanksto Principal, Mrs. Raji Jayaprasad, Aditya Birla publicschool, kovaya for her encouragement and for all thefacilities that she provided for this project work. Isincerely appreciate this magnanimity by taking me intoher fold for which I shall remain indebted to her.I extend my hearty thanks to Mr. B.D.KOTWANI,chemistry HOD, who guided me to the successfulcompletion of this project. I take this opportunity toexpress my deep sense of gratitude for his invaluableguidance, constant encouragement, constructivecomments, sympathetic attitude and immensemotivation, which has sustained my efforts at allstages of this project work. I am also thankful to Mr.Pankaj Bajpai who has helped in each step of myproject work.I can’t forget to offer my sincere thanks to myclassmates who helped me to carry out this projectwork successfully & for their valuable advice & support,which I received from them time to time.

ANURAG AGARWAL.

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DECLARATIONDeclaration

I do hereby declare that this project work hasbeen originally carried under the guidance andsupervision of Mr. B.D. KOTWANI, head ofchemistry department, Aditya Birla Public School,Kovaya.

ANURAG AGARWAL.

Roll NO.

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INDEXIndex

1) Certificate (ii)2) Acknowledgement (iii)3) Declaration (iv)4) Dedication (vi)5) Introduction 076) Aim 107) Requirements 108) Theory 119) Reactions 1210)Procedure 1311)Observations 1512)Result 1513)Bibliography 16iC

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DEDICATIONDedication

I DEDICATE THIS PROJECTWORK TO THE LOTUS FEET OF

MY FATHERMR.K.M.AGARWAL

&MY MOTHER

MRS. RAMA AGARWALiCB

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INTRODUCTIONIntroduction

Aluminium because of its low density, hightensile strength and resistance to corrosion is widely usedfor the manufacture of aeroplanes, automobiles lawnfurniture as well as for aluminium cans. Being goodconductor of electricity it is used for transmission ofelectricity. Aluminium is also used for making utensils.The recycling of aluminium cans and other aluminiumproducts is a very positive contribution to saving ournatural resources. Most of the recycled aluminium ismelted and recast into other aluminium metal products orused in the production of various aluminium compounds,the most common of which are the alums. Alums aredouble sulphates having general formula

X2SO4.M2(SO4)3.24H2O

X = Monovalent cation; M = Trivalent cation

Some important alum and their names are given below:

K2SO4.Al2(SO4)3.24H2O - Potash Alum

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Na2SO4.Al2(SO4)3.24H2O - Soda Alum

Introduction

K2SO4.Cr2(SO4)3.24H2O - Chrome Alum

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

Potash alum is used in papermaking, in fireextinguishers, in food stuffs and in purification of watersoda alum used in baking powders and chrome alum isused in tanning leather and water proofing fabrics.

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

i. An astringent a substance or preparation that drawstogether or constricts body tissues and is effective instopping the flow of blood or other secretions. Alum hasalso been used by conventional hairdressers for treatingshaving cuts,

ii. A mordant substances used in dyeing to fix certaindyes on cloth. Either the mordant (if it is colloidal) or acolloid produced by the mordant adheres to the fiber,attracting and fixing the colloidal mordant dye. Theinsoluble, colored precipitate that is formed is called alake. Alum is a basic mordant used for fixing acid dyes.

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Introduction

iii. For the removal of phosphate from natural andwaste waters the aluminium ions of alum combine withthe orthophosphate around pH 6 to form the solidaluminum hydroxyphosphate which is precipitated and

iv. For fireproofing fabrics The major uses of alums arebased on two important properties, namely precipitationof Al(OH)3 and those related to the acidity created by theproduction of hydrogen ions.

Al(H2O)6+3 → Al(OH)3 ↓ + 3H2O + 3H+

The H+ ions generated are used foe reacting with sodiumbicarbonate to release CO2. This property is made use ofin baking powder and CO2 fire extinguishers.

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AIMAim

To prepare potash alum from aluminium scrap

REQUIREMENTRequirement

250 ml flask

Funnel

Beaker

Scrap aluminium or cola can

Potassium hydroxide solution (KOH)

6 M Sulphuric Acid (H2SO4)

Water Bath

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Ethanol

THEORYTheory

Aluminum metal is treated with hot aqueous KOHsolution. Aluminium dissolves as potassium aluminate,KAl(OH)4, salt.

2Al(s) + 2KOH(aq) + 6H2O(l) 2KAl(OH)4 (aq) + 3H2

Potassium aluminate solution on treatment with dil.Sulphuric acid first gives precipitate Al(OH)3, whichdissolves on addition of small excess of H2SO4 andheating.

2KOH(aq) + H2SO4(aq) 2Al(OH)3 (s) + K2SO4(aq) + 2H2O(l)

2Al(OH)3 (s) + 3 H2SO4(aq) Al2(SO4)3(aq) +6H2O(l)

The resulting solution is concentrated to near saturationand cooled. On cooling crystals of potash alum crystallizeout.

K2SO4(aq) + Al2(SO4)3(aq) + 24H2O(l) K2SO4.Al2(SO4)3.24H2O(s)

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REACTIONSReactions

2Al(s) + 2KOH (aq) + 6H2O (l) 2KAl (OH)4 (aq) + 3H2


2Al(OH)3 (s) + 3 H2SO4(aq) Al2(SO4)3(aq) +6H2O(l)

2KOH(aq) + H2SO4(aq) 2Al(OH)3 (s) + K2SO4(aq) + 2H2O(l)


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PROCEDUREProcedure

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

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

The flask may be heated gently in order to facilitatedissolution. Since during this step hydrogen gas isevolved 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 impuritiesand reduce the volume to about 25 ml by heating.

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Allow the filtrate to cool. Now add slowly 6 MH2SO4 until insoluble Al(OH)3 just forms in the solution.

Procedure

Gently heat the mixture until the Al(OH)3 precipitatedissolves.

Cool the resulting solution in an ice-bath for about 30 minuteswhereby alum crystals should separate out. For better results thesolution may be left overnight for crystallization to continue.

In case crystals do not form the solution may be furtherconcentrated and cooled again.

Filter the crystals from the solution using vacuum pump, washthe crystals with 50/50 ethanol-water mixture.

Continue applying the vacuum until the crystals appear dry.

Determine the mass of alum crystals.

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OBSERVATION

Observation

Mass of aluminium metal =…………….g

Mass of potash alum =…………….g

Theoretical yield of potash alum =……………g

Percent yield =……………%

RESULTResult

Potash alum of % yield was prepared fromaluminium scrap.

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BIBLIOGRAPHY

Bibliography

iCBSE.com

Wikipedia,

Chemicalland.com

books.google.co.in

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chemistry project on preparation of potash alum

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