acknowledgementI owe my thanks to our principal for providing

laboratory facilities. And a tone of thanks to our

chemistry teacher for her valuable guidance and

providing the required app aratus 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 ofCaffeine in different samples of tea…..

Apparatus Required

CHEMICALS REQUIRED

1.Basic Lead Nitrate

3. Chlofororm

5. Animal Charcoal

2. Lead Oxide

4. Distilled water

6. Dilute Mineral Acid

TEA LEAVES OF THE

FOLLOWING VARIETIES

1. RED LABEL TEA (80gm)

2. TAJ MAHAL

TEA (80gm)

3. TATA TEA (80gm)

4. LIPTON

TEA (80gm)

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 color 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. The filtrate thus obtained is added

drop wise to this extract till no precipitation occurs.

The filtrate is treated with animal charcoal to decolorize 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 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 insolu ble lead sulphate as it is a basic oxide.

The activated 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.

OBSERVATIONAbout 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 OF THE TEA VARIETY

CAFFEINE CONTENTS

PERCENTAGE COMPOSITION

TASTE

REDLABEL

0.029 0.0725% MILD AND SOOTHING

TAJ MAHAL

0.05 0.0125% SLIGHTLY STRONG

TATA TEA

0.036 0.09% STRONG PLEASANT

LIPTON 0.047 0.1175%VERY STRONG

Bibliography1.Help from internet.

2. Information from library.

3.Help from teachers.

Chemistry INVERSTIGATORY Project

Chemistry INVERSTIGATORY Project

INDEXCERTIFICATE.ACKNOWLEDGEMENT.AIM.INTRODUCTION.APPARATUS & CHEMICALS REQUIRED.

PROCEDURE.OBSERVATION.INFERENCE.

INTRODUCTIONTea is a highly popular drink all over the world. A cup of tea is often taken as a mind-freshener. This can be primarily attributed to the presence of a stimulant called CAFFEINE in the tea. Besides this tea also contains various polyphenol compounds that act as flavorings 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. 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 called 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.