Preparation of Potash Alum

CENTRAL
ACADEMY
Submitted by: Vishal Bishnoi

Roll No.: 37
INDEX
➢ CERTIFICATE.
➢ ACKNOWLEDGEMENT.
➢ INTRODUCTION.
➢ AIM.
➢ REQUIREMENTS.
➢ THEORY.
➢ REACTIONS.
➢ PROCEDURE.
➢ OBSERVATIONS.
➢ RESULT.
➢ BIBLIOGRAPHY.
CERTIFICATE
It is hereby certified that, original
And genuine research work is carried
Out to investigate about the subject
matter and the related data
collection has been completed
satisfactorily by
“Vishal bishnoi” regarding the project
titled ‘preparation of potash alum.’
Mrs. Chetna Signature of

Ambedkar chemistry teacher
(Principal)
ACKNOWLEDGEMENT
I own my thanks to our

principal for providing laboratory
facilities,
And special thanks of gratitude
to my teacher Sir. Z.A.Ansari who
gave me the golden opportunity to
do this wonderful project, which
also helped me in doing a lot of
Research and I came to know
about so many new things I am
really thankful to them.
And a lot of thanks to my
friends, classmates and family
members who encouraged me in
doing this project successfully.
INTRODUCTION
Aluminum 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 aluminium cans. Being
good conductor of electricity it is used for
transmission of electricity. Aluminium is also used
cans and other aluminium product is a very
positive contribution to saving our natural
resources. Alums are double sulphates having
general formula…X2SO4M2(SO4)324H2O
X = Monovalent cation; M = Trivalent cation
Some important alum and their names are given
below:
K2SO4Al2(SO4)3.24H2O - Potash
Alum
Na2SO4.Al2 (SO4)3.24H2O - Soda
Alum
Potash alum is used in papermaking, in fire
extinguishers, in food stuffs and in purification of
water soda alum is used in baking powders and
chrome alum is used in tanning leather and water
proofing fabrics.
In addition to these primary uses, alum is also used
as,
1. An astringent substance or preparation that
draws together or consists body tissues and is
effective in stopping the flow of blood or other
secretions. Alum has also been used by
conventional hairdressers for treating shaving cuts.
2. A mordant substances used in dyeing to fix
certain dyes on cloth. Either mordant (if it is
colloidal) or a colloid produced by the mordant
adheres to the fiber, 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.
3. For fireproofing fabrics The major use of alums
are based on two important properties, namely
precipitation of Al(OH)3 and those related to the
acidity created by the production of hydrogen
ions.
AIM- To prepare potash alum.

REQUIREMENT
❖ 250 ml flask
❖ Funnel
❖ Beaker
❖ Scrap aluminium or cola can
❖ Potassium hydroxide solution (KOH)
❖ 6 M Sulphuric Acid (H2SO4)
❖ Water Bath
❖ Ethanol
THEORY
Aluminum metal is treated with hot aqueous KOH
solution. Aluminum dissolves as potassium
aluminate, KAl(OH)4, salt.
2Al + 2KOH +6H2O 2KAl(OH)4 +3H2

Potassium aluminate solution on treatment with
dil. Sulphuric acid first gives precipitate Al(OH)3,
which dissolves on addition of small excess of
2KOH + H2SO4 2Al(OH)3 + K2SO4

+2H2O
The resulting solution is concentrated to near
saturation and cooled. On cooling crystals of
potash alum is crystallize out.
K2SO4 + Al2(SO4)3 + 24H2O

K2SO4Al2(SO4)324H2O
REACTIONS
2AL + 2KOH + 6H2O 2KAl(OH)4 + 3H2
K2SO4 + Al2(SO4)3 + 24H2O K2SO4.Al2(SO4)3.24H2O
2Al(OH)3 + 3H2SO4 Al2(SO4)3 + 6H2O
2KOH + H2SO4 2Al(OH)3 + K2SO + 2H2O

PROCEDURE
1. Clean a small piece of scrap aluminium with
steel wool and cut it into very small pieces.
Aluminium foil may be taken instead of scrap
aluminium.
2. Put the small pieces of scrap aluminium or
aluminium foil (about 1.00g) into a conical flask
and add about 50 ml of 4 M KOH solution to
dissolve the aluminium.
3. The flask may be heated gently in order to
facilitate dissolution. Since during this step
hydrogen gas is evolved this step must be done in
a wall ventilated area.
4. Continue heating until all of the aluminium
reacts.
5. Filter the solution to remove any insoluble
impurities and reduce the volume to about 25ml
by heating.
6. Allow the filtrate to cool. Now add slowly 6 M
H2SO4 until insoluble Al(OH)3 just forms in
solution.
7. Gently heat the mixture until the Al(OH)3
precipitate dissolves.
8. Cool the resulting solution in an ice-bath about
30 minutes whereby alum crystals should separate
out. For better results the solution may be left
overnight for crystallization to continue.
9. In case crystals do not form the solution may be
further concentrated and cooled again.
10. Filter the crystals from the solution using
vacuum pump, wash the crystals with 50/50
ethanol-water mixture.
11. Continue applying the vacuum until the crystals
appears dry.
12. Determine the mass of alum crystals.
OBSERVATION
Mass of aluminium metal = …2.39 g

Mass of potash alum = …4.67g
Theoretical yield of potash alum = …5.43g
Percent yield = 86%
RESULT
Potash alum of 86% yield was prepared from

aluminium scrap
BIBLIOGRAPHY
✓ iCBSE.com
✓ Wikipedia.com
✓ Chemicalland.com
✓ Books.google.co.in

Preparation of Potash Alum

Uploaded by

Copyright:

Available Formats

Preparation of Potash Alum

Uploaded by

Document Information

Original Description:

Original Title

Copyright

Available Formats

Share this document

Share or Embed Document

Sharing Options

Did you find this document useful?

Is this content inappropriate?

Copyright:

Available Formats

Preparation of Potash Alum

Uploaded by

Copyright:

Available Formats

CENTRAL

Submitted by: Vishal Bishnoi

Mrs. Chetna Signature of

I own my thanks to our

AIM- To prepare potash alum.

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

2KOH + H2SO4 2Al(OH)3 + K2SO4

K2SO4 + Al2(SO4)3 + 24H2O

2AL + 2KOH + 6H2O 2KAl(OH)4 + 3H2

K2SO4 + Al2(SO4)3 + 24H2O K2SO4.Al2(SO4)3.24H2O

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

2KOH + H2SO4 2Al(OH)3 + K2SO + 2H2O

Mass of aluminium metal = …2.39 g

Potash alum of 86% yield was prepared from

You might also like