CERTIFICATE

This is to certify that Ritij Kumar Sah, of class XII of

INFOCUS INDIA PUBLIC SCHOOL has successfully
completed his/her project report in chemistry on the topic
“Sterilization of water using Bleaching powder...” for the
partial fulfillment of AISSCE as prescribed by the CBSE in the
year 2024 - 25.

Viva voce held on:

Registration No:

Signature of the Guide Signature of the principal

Signature of the Internal Signature of the Guide

Examiner Examiner
 ACKNOWLEDGEMENT

I would like to express my gratitude to all the people who have

helped me to successfully complete my project.

Firstly, I would like to express heartfelt gratitude to CBSE for

giving such a wonderful opportunity to create a project and gain
knowledge about this knowledgeable topic.

Secondly, I would like to thank my Chemistry Teacher

who helped me in every single aspect
during the preparation of this project.

And lastly, I would like to thank, all my teachers, my parents

and my friends who have been very supportive to me and for
which this project
has become such a successful one.
AIM OF THE PROJECT 5
INTRODUCTION 6
THEORY 8
REQUIREMENTS
PROCEDURE 10
OBSERVATIONS
RESULT 14
CONCLUSION 15
BIBLIOGRAPHY 16
Aim:
To determine the dosage of bleaching powder required for sterilization or
disinfection of different samples of water.

Introduction:

Need of 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.
 A daily average of 1 gallon per man is sufficient for drinking and cooking
purposes. A horse, bullock, or mule drinks about 11 gallons at a time.
Standing up, an average allowance of 5 gallons should be given for a man,
and 10 gallons for a horse or a camel.
 An elephant drinks 25 gallons, each mule or ox drinks 6 to 8 gallons, each
sheep or pig 6 to 8 pints. These are minimum quantities.

 In order to fulfill such a huge demand of water, it needs to be purified and

supplied in an 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.

Purification of Water:
There are many methods for the purification of water. Some of them are

 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.
Onemajor 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.
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”.

+ In 1854 it was discovered that a cholera epidemic spread through

water. The |
outbreak seemed less severe in areas where sand filters were installed. |
British scientist John Snow found that the direct cause of the outbreak
was |
water pump contamination by sewage water. He applied chlorine to
purify |
the water, and this paved the way for water disinfection.

sr Since the water in the pump had tasted and smelled normal, the
conclusion |
was finally drawn that good taste and smell alone do not guarantee safe
|
drinking water. This discovery led to governments starting to install
municipal water filters (sand filters and chlorination), and hence the
first
government regulation of public water.

«* In the 1890s America started building large sand filters to protect

public |
health. These turned out to be a success. Instead of slow sand filtration,
rapid sand filtration was now applied. Filter capacity was improved by
cleaning it with powerful jet steam.
ss Subsequently, Dr. Fuller found that rapid sand filtration worked
much better
when it was preceded by coagulation and sedimentation techniques. |
Meanwhile, such waterborne illnesses as cholera and typhoid became
less
and less common as water chlorination won terrain throughout the
world. |

s* But the victory obtained by the invention of chlorination did not last
long.
After some time the negative effects of this element were discovered.
Chlorine vaporizes much faster than water, and it was linked to the
aggravation and cause of respiratory disease.

= Water experts started looking for alternative water disinfectants. In

1902 |
calcium hypo chlorite and ferric chloride were mixed in a drinking
water |
supply in Belgium, resulting in both coagulation and disinfection. |

+ The treatment and distribution of water for safe use is one of the
greatest |
achievements of the twentieth century. Before cities began routinely
treating |
drinking water with chlorine (starting with Chicago and Jersey City in
US in |
1908), cholera, typhoid fever, dysentery and hepatitis wpe thousands of

U.S. residents annually.

** Drinking water chlorination and filtration have helped to virtually
eliminate |

these diseases in the U.S. and other developed countries. Meeting the
goal of |
clean, safe drinking water requires a multi-barrier approach that
includes:
protecting source water from contamination, appropriately treating raw
|
water, and ensuring safe distribution of treated water to consumers’
taps.
During the treatment process, chlorine is added to drinking water as |
elemental chlorine (chlorine gas), sodium hypochlorite solution or dry
calcium hypochlorite. When applied to water, each of these forms “free
chlorine,” which destroys pathogenic (disease-causing) organisms.
Almost all systems that disinfect their water use some type of chlorine-
based
process, either alone or in combination with other disinfectants. In
addition
to controlling disease-causing organisms, chlorination offers a number
of
benefits including:

Reduces many disagreeable tastes and odors;

Eliminates slime bacteria, molds and algae that
commonly grow in water supply reservoirs, on the
walls of water mains and in storage tanks;

Removes chemical compounds that have unpleasant

tastes and hinder disinfection; and

Helps remove iron and manganese from raw water.

As importantly, only chlorine-based chemicals provide “residual

disinfectant”
levels that prevent microbial re-growth and help protect treated water
throughout the distribution system.

For more than a century, the safety of drinking water supplies has been
greatly improved by the addition of bleaching powder. Disinfecting our
drinking water ensures it is free of the microorganisms that can cause |
serious and life-threatening diseases, such as cholera and typhoid fever.
To |
this day, bleaching powder remains the most commonly used drinking
water
disinfectant, and the disinfectant for which we have the most scientific |
information. Bleaching powder is added as part of the drinking water |
treatment process.

However, bleaching powder also reacts with the organic matter,

naturally
present in water, such as decaying leaves. This chemical reaction forms
a|
group of chemicals known as disinfection by-products. Current
scientific data |
shows that the benefits of bleaching our drinking water (less disease)
are
much greater than any health risks from THMs and other by-products.
Although other disinfectants are available, bleaching powder remains
the
choice of water treatment experts. When used with modeyn water
filtration
a ee ee a

methods, chlorine is effective against virtually all microorganisms.

Bleaching |
powder is easy to apply and small amounts of the chemical remain in
the |
water as it travels in the distribution system from the treatment plant to
the
consumer's tap, this level of effectiveness ensures that microorganisms
cannot recontaminate the water after it leaves the treatment.

‘** Bleaching powder or Calcium hypochlorite is a chemical compound

with
formula Ca(ClO),. It is widely used for water treatment and as a
bleaching
agent bleaching powder).

'» This chemical is considered to be relatively stable and has greater

available
chlorine than sodium hypochlorite (liquid bleach). It is prepared by
either |
calcium process or sodium process. |

Calcium Process

«= This chemical can be used for sterilizing water by Using 5 drops of

bleach per
each half gallon of water to be purified, and allowing it to sit
undisturbed for
half an hour to make it safe for drinking.

s* Letting it sit several hours more will help reduce the chlorine taste,
as the
chlorine will slowly evaporate out. A different reference advises when
using
household bleach for purification; add a single drop of bleach per quart
of |
water which is visibly clear, or three drops per quart of water where the
water is NOT visibly clear. Then allow the water to sit undisturbed for
half

an hour.
ss The combination of following processes is used for municipal
drinking water |
treatment worldwide:

Pre-chlorination - for algae control and arresting any biological

growth

Aeration - along with pre-chlorination for removal of

dissolved iron and manganese

Coagulation - for flocculation

Coagulant aids also known as polyelectrolyte’s - to improve

coagulation and for thicker floc formation

Sedimentation - for solid separation

Filtration - for removal of carried over floc

Disinfection - for killing bacteria

«« Out of these processes, the role of Bleaching powder is only in the

last step |
i.e. for Disinfection of water.

Requirements

a) Apparatus

= Burette,
titration flask
100ml graduated cylinder
250ml measuring flask
weight box
glazed tile

sx glass wool

b) Chemicals

sz Bleaching Powder

= Glass wool

= 0.1 N Na,S,0, solution

« 10% KI solution

Different samples of water

Starch solution.
|

ee ee en
ee i ee ee

| pre-Requisite Knowledge:

= A known mass of the given sample of bleaching powder is dissolved

in water
0 prepare a solution of known concentration. This solution contains
dissolved chlorine, liberated by the action of bleaching powder with
water.

f CaOCl,+H,0 —» Ca(OH),+Cl, — ‘|

= 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.

C4, +2KI > 2KCI+I,

I,+2Na,S,0, —> Na,S,0,+2Nal

= 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.

ss From the readings, the amount of chlorine and hence

required for the disinfection of a given volume of the given sample of
water
can be calculated.

Procedure

Preparation of Aeaching powder solution,

= Weigh accurately 2.5g of the given sample of bleaching powder and
transfer

it to a 250m! conical flask. Add about 100-150ml of distilled water.

Stopper
the flask and shake it vigorously. The suspension thus obtained is
filtered
through glass wool and the filtrate is diluted with water (in a measuring
flask) to make the volume 250ml. The solution obtained is 1%
bleaching

bleaching powder |

powder solution.
sx Take 20ml of bleaching powder solution in a stoppered conical flask
and add |

it to 20m! of 10% KI solution. Stopper the flask and shake it

vigorously.
Titrate this solution against 0.1N Na,S,0, solution taken in the burette.
When the solution in the conical flask becomes light yellow in color,
add |
about 2ml starch solution. The solution now becomes blue in color.
Continue
titrating till the blue color just disappears. Repeat the ti ation to get a set
of
three concordant readings.

Take 100ml of the water sample in a 250ml stoppered conical flask and
add

it to 10ml of bleching powder solution. Then add 20m of KI solution

and
stopper the flask. Shake vigorously and titrate
using starch solution as indicator.

Repeat the step 3 with other samples of water and record the
observations.
Observations

= Volume of bleaching powder solution taken is 20 ml.

= Volume of KI solution added is 20 ml.

= Volume of different samples of water is 100 ml

CBurette
reading
initial

10.1

10.1

18.4

18.4

26.6

Titration

CBurette
reading
initial

Final
‘Reading

15.1

25.2

25.2

35.2

35.2

Titration table for pond water

CBurette
reading
initial

0.2%

7.2

4.9

12.1

4.8

16.9

4.7
1) oank water ( Sample 1)
** amount of bleaching powder used to disinfect 100 ml of tap water

(8.2 - 10.1) ml of 0.2 N of Na,S,O, solution

= 1.9 ml of 0.2 N of Na,S,0, solution.

Since 250 ml bleaching powder solution contains 2.5 g bleaching
powder, 1ml
of bleaching powder solution contains 0.01g of bleaching powder.
20ml of bleaching powder solution consumes 8.2 ml of 0.2 N of
Na,S,0;
So 1 ml of Na,S,0, solution consumes 2.0 / 8.2 ml of bleaching powder
solution
Volume of bleaching powder solution used to disinfect 100 ml of water
= 1.9 x 20/8.2 ml
1.9.x 20/8.2 ml of bleaching powder solution contains 1.9 x 20x
0.01/8.2 g bleaching powder

Amount of bleaching powder to disinfect 1 litre of water is

19 x20x0.01x 1000
8.2x100

= 0.4634 gm

2) Pond water (Sample 2)

Amount of bleaching powder used to disinfect 100 ml of pond water

= (8.2 - 4.8) ml of 0.2 N Na,S,0, solution

= 3.4ml

Accordingly,
Volume of bleaching powder solution required to disinfect 1 litre of
water.

— 3.4x20x0.01x1000
8.2x 100

0.8293 g
Result

Amount of the giv

given sample of bleaching powder required to disinfect one litre

of water for

Tank water (Sample I) = 0.4634 g

Pond water (Sample II)= 0.8293 g

Since amount of bleaching powder required for disinfecting

POND WATER is more than a required for TANK WATER ,thus

It can be concluded that the former contains more impurities

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This is the convenient method of sterilizing water. It leaves

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@ http://www.vlib.us/medical /scancamp/water.htm
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wz http://en.wikipedia.org/wiki/bleaching_powder

= http:// en.wikipedia.org/wiki/water_treatment

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