The document describes an experiment to determine the dosage of bleaching powder required to sterilize different water samples. It includes a certificate of authenticity, acknowledgements, introduction on water purification techniques, theory on bleaching powder preparation, experimental procedure, observations, calculations and results. The key findings are that 0.215gm, 1.077gm and 1.231gm of bleaching powder are required to sterilize 1 liter of Bisleri water, rain water and borewell water respectively.

1. INDEX
1. Certificate of Authenticity
2. Acknowledgement
3. Introduction
-Need of Water
-Purification of Water
-Need for a stable purification technique
4. Theory
-Bleaching powder and its preparation
5. Experiment
-Aim
- Requirements
- Pre-Requisite Knowledge
-Procedure
6. Observation
7. Result
8. Bibliography

2. CERTIFICATE OF AUTHENTICITY
This is to certify that GAURAV SHARMA, a student of
class XII has successfully completed the research project in
chemistry on the topic “Sterilization of Water by using
Bleaching Powder” under the guidance of Mr.Madhav
Murthi (Subject Teacher) during the year 2014-15.
This project is absolutely genuine and does not indulge in plagiarism of
any kind. The references taken in making this project have been declared
at the end of this report.
Signature (Subject Teacher) Signature (Examiner)

3. ACKNOWLEDGEMENT
I wish to express my deep gratitude and sincere thanks to the
Principal, Mr. R Pramod for his encouragement and for all
the facilities that he provided for this project work. I
sincerely appreciate this magnanimity by taking me into his
fold for which I shall remain indebted to him. I extend my
hearty thanks to Mr.Madhav Murthi (teacher), who guided
me to the successful completion of this project. I take this
opportunity to express my deep sense of gratitude for his
valuable guidance, constant encouragement, immense
motivation, which has sustained my efforts at all the stages
of this project work.
I can’t forgot to offer my sincere thanks to Mr. S.Sekaran,
(lab assistant) and also to my classmates who helped me to
carry out this project work successful and for their valuable
advice and support , which I received from them time to
time.

4. INTRODUCTION
Need for Water
Water is an important and essential ingredient in our quest for
survival on this planet. It is very essential for carrying out various
metabolic processes in our body and also to carry out Hemoglobin
throughout the body.
In order to fulfill a huge demand of water, it needs to be purified and
supplied in a orderly and systematic way.
But with the increasing world population, the demand for drinking water has also
increased dramatically and therefore it is very essential to identify resources of
water from which we can use water for drinking purposes. Many available
resources of water do not have it in drinkable form. Either the water contains
excess of Calcium or Magnesium salts or any other organic impurity or it simply
contains foreign particles which make it unfit and unsafe for Drinking.

5. Purification of Water
There are many methods for the purification of water. Some of them are
1. Boiling
2. Filtration
3. Bleaching powder treatment
4. SODIS
Boiling is perhaps the most commonly used water purification technique in use
today. While in normal households it is an efficient technique; it cannot be
used for industrial and large scale purposes. It is because in normal
households, the water to be purified is very small in quantity and hence the
water loss due to evaporation is almost negligible. But in Industrial or large
scale purification of water the water loss due to evaporation will be quite high
and the amount of purified water obtained will be very less.
Filtration is also used for removing foreign particles from water. One major drawback
of this purification process is that it cannot be used for removing foreign
chemicals and impurities that are miscible with water.
SODIS or Solar Water Disinfection is recommended by the United Nations for
disinfection of water using soft drink bottles, sunlight, and a black surface-- at
least in hot nations with regularly intense sunlight.
Water-filled transparent bottles placed in a horizontal position atop a flat
surface in strong sunlight for around five hours will kill microbes in the
water. The process is made even more safe and effective if the bottom half of
the bottle or the surface it's lying on is blackened, and/or the flat surface is
made of plastic or metal. It's the combination of heat and ultraviolet light
which kills the organisms

6. The major drawback of this purification technique is that it cannot be used in
countries with cold weather. Also, the time consumed for Purification process is
more and it also needs a ‘blackened’ surface, much like solar cookers.
Need for a stable purification technique
Therefore we need a purification technique which can be used anytime and
anywhere, does not require the use of any third party content and which is also
economically feasible on both normal scale and large scale.
Hence we look at the method of purification of water using the technique of
treatment by bleaching powder commonly known as chlorination.

7. THEORY
PREPARATION OF BLEACHING POWDER:
It is prepared by either calcium process or sodium process.
Calcium Process: Calcium hypochlorite, also known as chloride of lime, is
made by reacting chlorine with calcium hydroxide:
2Cl2 + 2Ca(OH)2 → Ca(ClO)2 + CaCl2 + 2H2O
Sodium Process: Calcium hypochlorite is made by reacting chlorine with
sodium hydroxide:
2Ca(OH)2 + 3 Cl2 + 2 NaOH → Ca(OCl)2 + CaCl2 + 2 H2O + 2 NaCl
Bleaching powder is actually a mixture of calcium hypochlorite Ca(ClO)2
and the basic chloride CaCl2 , Ca(OH)2 , H2O with some slaked lime,
Ca(OH)2 .

8. Aim: To determine the dosage of bleaching powder
required for sterilization or disinfection of different
samples of water.
Requirements: Burette, titration flask, 100ml graduated
cylinder, 250ml measuring flask, weight box, glazed tile,
glass wool.
Chemicals required:
Bleaching Powder, Glass wool, 0.1 N Na2S2O3 solution, 10%
KI solution, different samples of water, starch solution.
EXPERIMENT

9. Pre-Requisite Knowledge:
1. A known mass of the given sample of bleaching powder is dissolved in water
to prepare a solution of known concentration. This solution contains dissolved
chlorine, liberated by the action of bleaching powder with water.
CaOCl2+H20 Ca(OH)2+Cl2
2. The amount of Chlorine present in the above solution is determined by
treating a known volume of the above solution with excess of 10% potassium
iodide solution, when equivalent amount of Iodine is liberated. The Iodine,
thus liberated is then estimated by titrating it against a standard solution of
Sodium thiosulphate, using starch solution as indicator.
3. A known Volume of one of the given samples of water is treated with a known
volume of bleaching powder solution. The amount of residual chlorine is
determined by adding excess potassium iodide solution and then titrating
against standard sodium thiosulphate solution.
4. From the readings in 2 and 3, the amount of chlorine and hence bleaching powder
required for the disinfection of a given volume of the given sample of water can be
calculated.
Cl2+2KI 2KCl + I2
I2+2Na2S2O3 Na2S4O6+2NaI

10. Procedure
1- Preparation of N/10 Na2SO4 solution :
Take 0.79gm of sodium thio-sulphate hydrated and dilute it in about
100ml of water . Equivalent mass of sodium thiosulphate solution =
Molecular mass/nfactor
= (158 g /mol)/2 = 79 g/mol
Normality = (number of gram equivalents of Na2SO4 )/Vol. Of
solutions(Lts)
1N----------79g------------1000ml water
1N/10----------7.9g-----------1000ml water
1N/10----------0.79g------------100ml water
2- Preparation of 10%KI solution :
Take 10gm. of KI powder and then dilute the mixture with water to
make the volume 100 ml and take it in the measuring flask.
3- Preparation of 1% Bleaching Powder solution :
Weight 2.5gm of bleaching powder and mix it in about 200 ml of
distilled water in a conical flask. Stopper the flask and shake it
vigorously. The suspension thus obtained is filtered through glass
wool in measuring flask of 500ml. and dilute the filtrate with water to
make the volume 250 ml. The solution of obtained is 1% bleaching
powder of solution.
4- Preparation of starch solution :
Take about 1gm of soluble starch and 10 ml of distilled water in a test
table. Mix vigorously to obtain a paste. Pour the paste in about
100ml. of hot water contained in a beaker with constant stirring. Boil
the contents for 4-5 minutes and then allow to cool.

11. TITRATION:
5- TITRATION-1(WATER SAMPLE: Distilled Water) :
Take 100ml. of distilled of water and then 20ml of bleaching powder
of solution in a stopper conical flask and add to it 20ml of 10% KI
solution. Shake the mixture, titrate this solution against N/10
Na2S2O3. Sodium thio-sulphate solution taken in burette. When
solution in the conical flask becomes light yellow in colour add about
2ml of starch solution as indicator. The solution now becomes blue in
colour. The end point is disappearance of blue colour, so continue

12. titrating till the blue colour just disappears. Repeat the titration to get a set
of two concordant readings.
6- TITRATION-(WATER SAMPLE-Bisleri Water, Rain Water, Borewell
water) :
Take 100ml of water sample in a conical flask, add 20ml of bleaching
powder of solution in a stopper conical flask and add 20ml of KI
solution and stopper the flask. Shake it and titrates against N/10
Na2S2O3 until the solution become yellow. Then add 2ml of starch
solution and then again titrate till the blue colour disappears. Repeat
titration to get a set of two concordant readings.
7- Repeat the step 6 with other samples of water and record the
observation.

13. OBSERVATIONS
Burette solution: Sodium Thiosulphate
Titrated against: 20ml(bleaching powder solution)+20ml KI + 100ml(Water Sample)
Indicator: Starch
End point: Blue colour to colourless solution
Titration : I
 Volume of Distilled water taken 100ml
 Volume of bleaching powder sol. taken 20ml
 Volume of KI solution added 20ml
Burette Reading
Sr.N
o.
Initial ( in ml) Final ( in ml) Final Vol. of 0.1N Na2S2O3 sol.
Used ( in ml)
1. 0.0 6.5 6.5
2. 6.50 13.0 6.5
Concordant Reading:6.5ml
Titration : II
 Volume of water sample I taken 100ml
 Volume of bleaching powder sol. added 20ml
 Volume of KI solution added 20ml
Burette Reading
Sr.N
o.
Initial ( in ml) Final ( in ml) Final Vol. of 0.2N Na2S2O3
sol.
Used ( in ml)
1. 0.0 5.8 5.8
2. 5.8 11.6 5.8
Concordant Reading:5.8ml

14. Titration: III
 Volume of water sample II taken 100ml
 Volume of bleaching powder sol. added 20ml
 Volume of KI solution added 20ml
Burette Reading
Sr.N
o.
Initial ( in ml) Final ( in ml) Final Vol. of 0.2N Na2S2O3
sol.
Used ( in ml)
1. 0.0 3.0 3.0
2. 3.0 6.0 3.0
Concordant Reading:3.0ml
Titration : IV
 Volume of water sample III taken 100ml
 Volume of bleaching powder sol. added 20ml
 Volume of KI solution added 20ml
Burette Reading
Sr.N
o.
Initial ( in ml) Final ( in ml) Final Vol. of 0.2N Na2S2O3
sol.
Used ( in ml)
1. 0.0 2.5 2.5
2. 2.5 5.0 2.5
Concordant Reading:2.5ml

15. CALCULATIONS
Sample I (BISLERI WATER) :-
 Amount of bleaching powder used to disinfect 100ml of water.
= (6.5 - 5.8 ) = 0.7ml of 0.1 N of Na2S2O3 solutions.
 1 ml of bleaching powder solution contains bleaching powder.
= 2.5/250 = 0.01gm
 20 ml of bleaching powder solution = 2.5 ml of 0.1 Na2S2O3
 So, 1ml of 0.1 N Na2S2O3 solution = 20/2.5 ml of bleaching powder
solution
 Volume of bleaching powder solution required to disinfect 100ml of
water sample I
= 0.7 x 20/6.5 ml.
 0.7 x 20/6.5 ml of bleaching powder solution
= ((0.7 x 20) / 6.5) x 0.01 gm of bleaching powder
 Amount of bleaching powder required to disinfect 1 ltr. of water
sample I
= 0.7 x (20/6.5) x ((0.01 x 1000 ) / (100))g = 1.4/6.5 = 0.215gm
Sample II (RAIN WATER)
 Amount of bleaching powder used to disinfect 100ml of water.
= (6.5 - 3.0 ) = 3.5ml of 0.1 N of Na2S2O3 solutions.
 1 ml of bleaching powder solution contains bleaching powder.
= 2.5/250 = 0.01gm
 20 ml of bleaching powder solution = 2.5 ml of 0.1 Na2S2O3
 So, 1ml of 0.1 N Na2S2O3 solution = 20/2.5 ml of bleaching powder
solution
 Volume of bleaching powder solution required to disinfect 100ml of
water sample I
= 3.5 x 20/6.5 ml.

16. 3.5 x 20/6.5 ml of bleaching powder solution
= ((3.5 x 20) / 6.5) x 0.01 gm of bleaching powder
 Amount of bleaching powder required to disinfect 1 ltr. of water
sample I
= 3.5 x (20/6.5) x ((0.01 x 1000 )/(100))g = 7.0/6.5g = 1.077gm
Sample III (BOREWELL WATER) :-
 Amount of bleaching powder used to disinfect 100ml of water.
= (6.5 - 2.5 ) = 4.0ml of 0.1 N of Na2S2O3 solutions.
 1 ml of bleaching powder solution contains bleaching powder.
= 2.5/250 = 0.01gm
 20 ml of bleaching powder solution = 2.5 ml of 0.1 Na2S2O3
 So, 1ml of 0.1 N Na2S2O3 solution = 20/2.5 ml of bleaching powder
solution
 Volume of bleaching powder solution required to disinfect 100ml of
water sample I
= 4.0 x 20/6.5 ml.
 4.0 x 20/6.5 ml of bleaching powder solution
= ((4.0 x 20) / 6.5) x 0.01 gm of bleaching powder
 Amount of bleaching powder required to disinfect 1 ltr. of water
sample I
= 4.0 x (20/6.5) x ((0.01 x 1000 ) / (100))g = 8.0/6.5= 1.231gm

17. RESULT
Amount of the given samples of bleaching powder required to disinfect
one litre of water:
Sample I = 0.215gm
Sample II = 1.077gm
Sample III = 1.231gm
Thus we get the amount required for disinfection and if bleaching powder
is taken less than this amount water will remain impure and if it taken in
excess than this will also be harmful as it will contain chlorine.
The results shows that Samples III is the more impure water as the amount
of bleaching powder required is maximum and Sample I is less impure
than others as the bleaching powder required is minimum.
The tables also show the difference. Titration IV has minimum reading
because of impurities and titration I has maximum reading because the
sample was distilled water.

18. BIBLIOGRAPHY / WEBLIOGRAPHY
1.www.icbse.com
2.http:/en.wikipedia.org/wiki/bleaching
3.http:/en.wikipedia.org/wiki/watertreatment
4.www.edstorm.com/doclib/mi4174.pdf