CHEMISTRY
INVERSTIGATORY
PROJECT
Name: Durjay
Tabiyar
Class: XII-A
School:
K.V.NO.2
INDEX
CERTIFICATE.
ACKNOWLEDGEMENT.
AIM.
INTRODUCTION.
APPARATUS & CHEMICALS
REQUIRED.
PROCEDURE.
OBSERVATION. INFERENCE.
KENDRIYA VIDYALAYA
Eklinggarh no.2
CERTIFICATE
Certified by the DEPARTMENT OF
CHEMISTRY that it is a bonified project
conducted by
DURJAY TABIYAR Of CLASS XII-A
During the ACADEMIC YEAR 2024-25
conducted by CBSE, NEW DELHI.
Signature of external Signature of
chemistry
Examiner teacher
ACKNOWLEDGEMENT
I owe my thanks to our principal
for providing laboratory facilities.
And a tone of thanks to
for his valuable guidance and providing
the required apparatus to perform my
project work.
And a lot of thanks to my friends,
classmates and family members who
encouraged me in doing this project
successfully.
AIM
TO DETERMINE
THE PERCENTAGE
OF CAFFEINE IN
DIFFERENT
SAMPLES OF
TEA…
INTRODUCTION
Tea is a highly popular drink all over the
world.
A cup of tea is often taken as a mind-
freshner.
This can be primarily attributed to the
presence of a stimulant called
CAFFEINE in the tea.
Besides this tea also contains
various polyphenolic compounds that act
as flavourings
agents. Relative contents of these
compounds result in different
varieties available under different
brand names.
The quality of tea leaves also greatly
influence of the taste of the
tea.
Tea is popular name of the tropical plant
whose botanical name is Camellia thea.
India is the largest producer of good
quality tea and it is mainly grown in
slope of hills of Assam, West Bengal
and Nilgiri Hills. A cup of Indian tea
contains 80mg of caffeine which is the
indispensable content of tea.
Caffeine is a nitrogenous organic
compound of alkaloid group. These
groups of substances have a marked
physiological effect on the human
body when taken in considerable
amount. It is widely used as a stimulant
of the
central nervous system and also has
hypotonic
and sleep inducing effect. Pure caffeine
has the
general formula C8H10N402. IUPAC
name of this substance is 1, 3, 7-
trimethyl xanthamine.
It occurs as a white powder that melts at
around
2380C. It is fairly soluble in hot water
and on cooling the solution gives
crystals made up of caffeine
monohydrate. In this case the
compound is less soluble in organic
solvents
than in hot water. It is odorless but even
a small
amount have a very bitter taste.
Caffeine is the main flavoring agent in
the tea leaves. It is obtained from the
decaffeination of tea dust and also
from coffee.
It exerts a simulative effect on the
cerebral cortex but later has a
depressant and narcotic action. It is
also useful in cardiac dropsy. An
abnormal sate arising from caffeine is
callrd caffeinism. The main symptoms
are
nervousness, Insomnia and
Tachycardia. It is used in medicines
in the form of chlorides and nitrates.
In this project we will do a careful
study of different brands of tea and
will extract and
carefully analyze their caffeine
content. The
result would thus tell the exact
content of caffeine present in
different samples analyzed.
APPARATUS REQUIRED
1.ROUND BOTTOM
FLASK.
2.BUNSEN
BURNER, MATCH STICK.
3.BEAKERS.
(250ml AND 75
ml)
CHEMICALS REQUIRED
1.Basic Lead 2. Lead Oxide
Nitrate
3. Chlofororm 4. Distilled
water
5. Animal Charcoal 6. Dilute Mineral Acid
Procedure
In a litre round bottom flask 40gm of first sample
was taken.
To this about 250ml of distilled water was added
and the contents were refluxed for about an
hour.
The brown colour extracted is separated by
decantation followed by filtration when still hot.
Lead acetate is dissolved into water in 250ml
beaker.
The solution is boiled and the lead oxide is
added slowly to the boiling solution with
constant stirring.
It is filtered and again boiled.
The filterate thus obtained is added dropwise to
this extract till no precipitation occurs.
The filtrate is treated with animal charcoal to
decolourise extract.
The clear solution is extracted with 100mg of
chloroform after separating by filtration.
The total solution is taken into distillation flask
to remove the solvent by distillation.
The residue left in the flask is dissolved in
minimum amount of hot water and the dissolved
contents are transferred to the boiling tube.
The solution is kept for slow crystallization.
When the white crystalline solid comes out of
the solution it is filtered, dried in desiccators and
weighed.
The above procedure is repeated for all samples
of tea. The observations are carefully recorded.
The chemistry involved in the
experiment is as follows:
Caffeine being soluble in water
goes into the solution on refluxing.
Lead oxide when added to lead
acetate solution helps lead to
precipitate and come out in the
form of insoluble lead sulphate as
it is a basic oxide.
Theactivated charcoal adsorbs the
coloured pigments from the brown
coloured solution.
Chloroform is used for extracting
the caffeine as it is a more soluble
in CHCl3 than in cold water.
On boiling caffeine being more
volatile evaporates leaving a white
mass behind.
On adding more chloroform and by
gradual evaporation we get nice
crystalline caffeine.
OBSERVATION
About 49gm of each sample was taken.
The contents of caffeine of the samples
were noted and their presence in terms of
percentage was calculated.
NAME CAFFEINE PERCENTAG TASTE
OF CONTENT E
THE TEA S COMPOSITIO
VARIETY N
RED 0.029 0.0725% MILD AND
SOOTHING
LABEL
TAJ 0.05 0.0125% SLIGHTLY
MAHAL STRONG
TATA 0.036 0.09% STRONG
PLEASANT
TEA
VERY
LIPTON 0.047 0.1175% STRONG
INFERENCE
FROM THE CAFFEINE
CONTENT AND THE TASTE
OF THE TEA AS DESCRIBED
ABOVE SHOWS THAT THE
GREATER THE AMOUNT OF
CAFFEINE, THE
BITTERNESS AND
STIMULATING EFFECT OF
THE TEA.
Bibliography
1. Help from
internet.
2. Information from
library.
3. Help from
teachers.
durjay tabiyar
xii-A
