Chemistry Project ~~~~~~~~~
Submitted by Radhika H XII B
CHINMAYA VIDYALAYA VADUTHALA CHEMISTRY PROJECT WORK CERTIFICATE
This is to certify that ………………………………… Roll no……… of Class……… Division……… has completed the project work during the academic year ………………….
REMARKS: DEPARTMENT:
…………… Instructor in Charge
…………… Head of the Department
DATE: ……………
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…………… Principal
INDEX
ACKNOWLEDGEMENT……………………
4
INTRODUCTION……………………………
5
EXPERIMENTS……………………………… 6
BIBLIOGRAPHY………………………………8
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ACKNOWLEDGEMENT I would like to convey our sincere gratitude to the Principal Ms. Maya Mohan for letting us do this project. I would like to thank Mrs. Susheela John, The Head of the Department, Mr. Girish and Mrs. rs. Rekh Rekha a for for guid idin ing g and and in inst stru ruct ctin ing g us throughout the project. I would also like to thank Mr. Anil for all his help. Last but not the leas east, I would like to thank all my friends for helping me with this project.
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INTRODUCTION Tea is made from the young leaves and buds of the tea plant. Tea leaves are rich in caffei caffeine ne (an (an alkalo alkaloid) id).. Beside Besides s caffei caffeine, ne, tea leaves also contain tannic acid and coloring matt matter er,, su such ch as poly polyph phen enol olic ic com compoun pounds ds.. The relative amounts of these substances are different in different varieties of tea leaves, which is why, their tastes and flavours are different. The brownish color of the tea is due to the presence of polyphenolic compounds and some organic ions like Mn+2, Fe+3, etc. Some simp imple exper xperim imen entts can can be carr carrie ied d out to study study the compon component ents s that that are respo responsi nsible ble for for the the vari varia ation ion in tea flav flavo our in vari vario ous brands of tea.
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EXPERIMENT - I AIM: Compare the water soluble polyphenol (catechin) content in various samples of tea leaves. REQUIREMENTS: Beak Beaker ers, s, coni conica call flas flasks ks,, funn funnel els, s, heating arrangement, tea bags of different brands of tea. THEORY: Tea contains upto 30% of the water soluble polyphenols (catechin). These are largely responsible for the flavour of the tea. To estimate the extent of these compounds in a given sample, the tea leaves are immersed in hot water for equal time and the loss in weight of tea leaves is determined. PROCEDURE: 1. Weigh exactly 3 g of each of the different samples of tea and place them in tea bags. 2. Take Take three or four conica conicall flasks flasks and and put 100 ml of hot water into each of them. 3. Put tea bags of different samples of tea in the different conical flasks. After 10 minutes, remove 6
the tea bags and dry them by placing them in an oven. 4. When the the tea bags bags become become dry, reweigh them. 5. Note the the flavour of the tea solution solution obtained. obtained.
OBSERVATIONS:
1.
TYPE R
3
2.3652
0.6348
% OF WATER SOL. COMP. = y/x X 100 78.84 %
2.
TYPE G
3
2.9940
0.0060
99.8 %
3.
TYPE S
3
2.6400
0.3600
88 %
SL NO.
BRAND NAME
INITIAL WEIGHT(x g)
FINAL WEIGHT (y g)
LOSS OF WEIGHT
RESULT: The tea having better taste has more polyphenol content.
EXPERIMENT - II AIM: Comp Compar are e the the tann tannic ic acid acid cont conten entt of vario arious us samples of tea. REQUIREMENTS: Beak Beaker ers, s, coni conica call flas flasks ks,, funn funnel els, s, heating arrangement, various samples of tea, calcium carbonate, conc. HCl. THEORY: The The tann tannic ic acid acid pres presen entt in tea tea leav leaves es is prec recip ipiitat tated as calc alciu ium m tannate ate by treat reatm ment ent of aqu aqueous ous solu luti tion on of tea tea with calc alciu ium m carb arbona onate. te. Calcium tannate is then hydrolyzed with conc. HCl and recrystallised recrystallised from water. PROCEDURE: 7
1. Weig Weigh h 10 10g g of each of the the gi give ven n samp sample les s of tea leaves. 2. Take ake 100 ml of disti istillled led wate ater in a 400 ml of beaker and boil it. Then add the first sample of tea leaves to it and boil it for 10 minutes. Cool and filter the solution. 3. To To the the filt filtra rate te,, add add abou aboutt 2g of soli solid d calc calciu ium m carbonate and boil the contents. Tannic acid gets prec precip ipit itat ated ed as calc calciu ium m tann tannat ate. e. Sepa Separa rate te the the precipitate of calcium tannate by filtration. 4. Calc Calciu ium m tann tannat ate e obta obtain ined ed is hydr hydrol olyz yzed ed by warming with 4-5ml of conc. HCl. The tannic acid obtained is crystallized from water and weighed. 5. Repeat the steps 2, 3 and 4 with the other samples of tea and recode the observations. observations.
OBSERVATIONS: Sl BRAND NAME No OF TEA . 1. TYPE R
WEIGHT. OF TEA LEAVES TAKEN (x g) 10
2.
TYPE G
10
3.
TYPE S
10
WEIGHT OF TANNIC ACID OBTAINED (y g)
% OF TANNIC ACID = y/x X 100
RESULT: The RESULT: The tea sample containing highest percentage of tannic acid gives better flavour.
BIBLIOGRAPHY Comprehensive
Chemistry Practical
Guide Together With Chemistry Practical Guide www.sciencebuddies.org 8
www.teatalk.com
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