Oxalate Nirbhay.pdf

8/13/2019 Oxalate Nirbhay.pdf

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ACKNOWLEDGEMENT

I hereby acknowledge my deep sense of gratitude and

indebtedness to Mr. Chanchal Singh,PGT(Chemistry) whose

immense help, genius guidance, encouragement, necessary

suggestions, initiations, enthusiasm and inspiration made this

work a master art.

This project was very innovative and exciting for me. I could bringit out successfully and so I am thankful to many people.

I would also like to thank my friends and family, for supporting me

morally. Last but not the least, I would like to thank my institution

for allowing me to do this project and for providing me with all the

necessary chemicals that were required. It is all due to the

support and concern of the above people and institution that Icould complete my investigator project satisfactorily, without

which things would have never gone well.

Nirbhay Singh


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CERTIFICATE

This is to certify that Nirbhay Singh,XII of Allahabad PublicSchool and Colleage,session 2013-14 has satisfactorilycompleted his chemistry project on Study of presence ofOxalate ion in guava fruit at different stages of ripening as

per the syllabus under my guidance.

Chemistry Teacher External ExaminersMr. Chanchal Singh Signature(PGT-Chemistry)

CONTENTS

Introduction


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Benefits And Uses of GuavaProperties / Actions Documented by Research

Guava fruit actions Drug Interactions

Contraindications

What is Oxalate ? Structure

Requirements Apparatus

Chemicals required

Theory Redox titration

Chemical Equations Molecular equations

Ionic equations

ProcedureObservationsCalculations

ConclusionPrecautionsBibliography


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To study the presence of Oxalate ions in Guavafruit at different stages of ripening

INTRODUCTION

Guava or psidum guajava is one of the various my

staceous trees or shrubs of the genus psidum. When ripe,

it has dark or light green-colored peel which turns light

yellow on ripening, the pulp of the fruit is cream coloredwith many seeds embedded in it. Guava has the highest

percentage of vitamin C among all citrus fruit. It also

contains oxalates, amount of which varies during ripening

of fruit. During the process of removal of two equivalent

hydrogen of vitamin C (Ascorbic acid) molecules take

place.Dehydroascorbic acid is further oxidized to oxalic

acid in alkaline medium.


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BENEFITS ND USES OF GU V

1. Guavas are an excellent source of vitamin C andalsocontain iron calcium, and phosphorus. The guavafruitcontains the highest vitamin C content out of all thecitrus fruits with as much as 180 mg per 100 g if fruit.

2. Older children and adults, a cup once or twice daily of a

leaf decoction is the tropical herbal medicine standard.

3. A guava leaf decoction is taken to relieve colds andbronchitis.


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4. The roots, bark, leaves and immature fruits, becauseof their astringency, are commonly employed tohaltgastroenteritis, diarrhea, dysentery and vomiting in

cholera patients.

5. It also has hypoglycemic and anti bacterialproperties.The fruit, when eaten whole helps reduce both,high blood pressure and cholesterol levels.

6. Guava benefits in battling diabetes, combats cancerand protects prostate.

7. Guava can improve heart health by helping to controlblood pressure and cholesterol.

8. Guava is highly effective in removing constipation.PROPERTIES / ACTIONS DOCUMENTED

BY RESEARCHGuava fruit acts as aAmebicide, analgesic (pain reliever), antibacterial, anticandidal,

antidysenteric, antifungal, antimalarial, antioxidant,

antispasmodic, antiulcerous, cardio depressant, cardiotonic

(tones, balances, strengthens the heart), central nervoussystem depressant, cough suppressant, gastrototonic (tones,

balances, strengthens the gastric tract), hypotensive (lowers

blood pressure), sedative, vasoconstrictor).


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Other Properties/Actions Documented by

Traditional UseGuava fruit also has the following effects on human health:

Anti-anxiety, anticonvulsant, antiseptic, astringent, blood

cleanser, digestive stimulant, menstrual stimulant, neervine

(balances / calms nerves), vermifuge (expels worms).

Drug Interactions:

None reported, however excessive or chronic consumption of

guava may potentiate some heart medications.

Main Actions (in order):

Antidysenteric, antiseptic, antibacterial, antispasmodic,

cardiotonic (tones, balances, strengthens the heart).

Contraindications:

1. Guava has recently demonstrated cardiac depressant activity

and should be used with caution by those on heart

medications.


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2. Guava fruit has shown to lower blood sugar levels and it

should be avoided by people with hypoglycemia.


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WHAT IS OXALATE ?

Oxalate (IUPAC: ethanedioate) is the dianion with theformula C2O4

2, also written (COO)2

2. Either name is

often used for derivatives, such as salts of oxalic acid (forexample sodium oxalate, ((Na+)2C2O4

2) or esters thereof

(for example dimethyl oxalate, ((CH3)2C2O4). Oxalate alsoforms coordination compounds where it is sometimesabbreviated as ox.

Oxalate is an organic acid, primarily found in plants,animals and humans. It is not an essential molecule and isexcreted from our body in an unchanged form. Our bodyeither produces oxalate on its own or it converts othermolecules like vitamin C to oxalate.External sources likethe foods we eat also contribute to the accumulation of

oxalate in our body. The oxalate present in the body isexcreted in our urine as a waste. Too much of oxalate inour urine,results in a medical condition called ashyperoxaluria, commonly referred to as kidney stones.


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Diet is looked upon as a preventive measure in addition to

medicines to treat kidney stones.

Structure

X-ray crystallography of simple oxalate salts show that theoxalate anion may adopt either a planar conformation withD2h molecular symmetry, or a conformation where the O-C-C-O dihedrals approach 90 with approximate D2d

symmetry.Specifically, the oxalate moiety adopts theplanar, D2h conformation in the solid-state structures ofM2C2O4(M = Li, Na, K).However, in structure of Cs2C2O4the O-C-C-O dihedral angle is 81(1). Therefore, Cs2C2O4


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is more closely approximated by a D2d symmetry structurebecause the two CO2planes are staggered. Interestingly,

two forms of Rb2C2O4have been structurally characterizedby single-crystal, X-ray diffraction: one contains a planarand the other a staggered oxalate.

As the preceding examples indicate that the conformationadopted by the oxalate dianion is dependent upon the sizeof the alkali metal to which it is bound, some haveexplored the barrier to rotation about the central CCbond. It was determined computationally that barrier to

rotation about this bond is roughly 26 kcal/mole for thefree dianion, C2O4

2.[6] Such results are consistent with

the interpretation that the central carbon-carbon bond isbest regarded as a single bond with only minimal piinteractions between the two CO2units.This barrier torotation about the CC bond (which formally correspondsto the difference in energy between the planar and

staggered forms) may be attributed to electrostaticinteractions as unfavorable OO repulsion is maximized inthe planar form.It is important to note that oxalate is often encountered asa bidentate, chelating ligand, such as in potassiumferrioxalate. When the oxalate chelates to a single metalcenter, it always adopts the planar conformation.


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REQUIREMENTS

(A)Apparatus

100 ml measuring flaskPestleMortarBeakerTitration flaskFunnel

BuretteWeight boxFilter paper

(B)Chemicals Required

Dilute H2SO4

N/20 KMnO4 solutionGuava fruits at different stages of ripening.

THEORY


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Oxalate ions are extracted from the fruit by boiling pulpwith dil.H2SO4.Then oxalate ions are estimated

volumetrically by titrating the solution with standardKMnO4solution.Titration is a common laboratory methodof quantitative chemical analysis that is used to determinethe unknown concentration of a known reactant. Becausevolume measurements play a key role in titration, it is alsoknown as volumetric analysis. A reagent, called the titrantor titrator, of a known concentration (a standard solution)and volume is used to react with a solution of the analyte

or titrand, whose concentration is not known. Using acalibrated burette or chemistry pipetting syringe to add thetitrant, it is possible to determine the exact amount thathas been consumed when the endpoint is reached. Theendpoint is the point at which the titration is complete, asdetermined by an indicator. This is ideally the samevolume as the equivalence point-the volume of added

titrant at which the number of moles of titrant is equal tothe number of moles of analyte.In the classic strong acid-strong base titration,the endpoint of a titration is the pointat which the pH of the reactant is just about equal to 7,and often when the solution takes on a persisting solidcolour as in the pink of phenolphthalein indicator.

Redox titration


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Redox titration (also called oxidation reduction titration ) isa type of titration based on a redox reaction between theanalyte and titrant.

It is a titration of a reducing agent by an oxidizing agentbetween the analyte and titrant.Redox reaction may involve the use of a redox indicator.This experiment involves the use of potassiumpermanganate which is the oxidizing agent as well as theindicator.Permanganate ion is a powerful oxidizing agent, especiallyin acidic solution, which can be used to analyze (by

titration ) solutions containing many different species. Inthese titration reactions, the intensely colored MnO4

-ion is

reduced to form the colorless Mn+2ion.An advantage of using the permanganate ion in thetitration of colorless unknown solutions is that it is selfindicating. As long as the reducing agent remains presentin the sample, the color of MnO4

-quickly disappears as it

is reduced toMn

+2. However, at the endpoint, all the reducing agent has

been used up so the next drop of MnO4-solution is

sufficient to cause an easily detected color change,colorless (faint, permanent peach / pink ). So we know thatat the endpoint, the oxidizing agent (MnO4

-4) and reducing

agent (H2O2or Fe+2

) have reacted in exactly in proportionto their stoichiometry in the balanced redox equation. If weknow how much of the oxidizing agent we added, then wecan figure out exactly how much reducing agent waspresent in the unknown


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(1) Weighed 50 g of fresh guava and crushed it to a finepulp using pestle and mortar.

(2) Transferred the crushed pulp to a beaker and addedabout 50 ml dilute H2SO4 to it.

(3) Boiled the content for about 10 minutes. Cooled andfiltered the contents in a 100 ml measuring flask.

(4) Made up the volume 100 ml by adding ample amountof distilled water.

(5) Took 20 ml of the solution from the flask and added 20ml of dilute sulphuric acid to it.

(6) Heated the mixture to about 600 C and titrated it

against (n/10) KMnO4 solution taken in a burette till theend point had an appearance of pink colour.

(7) Repeated the above experiment with 50 g of 1day, 2day and 3 day old guava fruits.

OBSERV TIONS


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1. Weight of the guava fruit for each time was 50 g.

2. Volume of guava extract taken for each titration was 20 ml.

3. Normality of KMnO4 solution was (1/10).

4. END POINT: Colour Changes to pink

GuavaSolution

BurettereadingInitial

FinalReading

Volume ofKMnO4

ConcurrentReading

Raw 150 18 132136.06Semi-ripened 150 13 137

Ripened 150 10.8 139.2

CALCULATIONS

1.For raw guava

N1V1= N2V2N1x 10 = (1/10) x1321/10 x Normality of oxalate = (x/100) = strength ofoxalate in fresh guava extract = normality x Eq. mass ofoxalate ion

= 1.32/100 x 44g/litre of diluted extract= 0.581 g L-1

2) For semi ripened guava (1 day old).


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Strength of oxalate in one day old guava extract= (1.37 /100) x 44g/litre of diluted extract= 0.603 g L-1

3) For ripened guava

Strength of oxalate in fresh guava extract = ( 1.39/100) x44g/litre of diluted extract= 0.612 g L-1(a) The normality of oxalate ions of;

(i) Fresh guava solution is = 1.32 ml(ii) Semi-ripen guava solution is = 1.37 ml(iii) Ripened guava solution is = 1.39 ml(b) The strength of oxalate ions of;(i) Fresh guava solution is = 0.58 ml(ii) Semi-ripened guava is = 0.60 ml(iii) Ripened guava is = 0.61 ml

The content of oxalate ions in guava was found to be59.67 per cent, which is close to the literature value of 60percent.It was also noticed that the content of oxalic ions growswith ripening of guava.

CONCLUSIONS


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The content of oxalate ions in guava was found to be59.67 per cent, which is close to the literature value of 60percent.

It was also noticed that the content of oxalic ions growswith ripening of guava.

PRECAUTIONS

1. KMnO4 solution is always taken in the burette.

2.Avoid the use of burette having a rubber tap as KMnO4Attacks rubber.

3.In order to get some idea about the temperature of thesolution touch the flask to the back side of your hand.When it becomes unbearable to touch, the requiredtemperature is reached.

4.Add about an equal volume of dil. H2SO4to the guava extract to be titrated (say a full test tube)before adding KMnO4.

5.Read the upper meniscus while taking burette readingwith KMnO4solution.

6.In case, on addition of KMnO4a brown ppt. appears, thisshows that either H2SO4has not been added or has been


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www.wikipedia.com

www.reader.google.com

www.labs.google.com

www.quora.com

2. Practical Chemistry by Laxmi Publications.

3. The Family Encyclopedia by Dorling Kindersley.
http://www.wikipedia.com/http://www.reader.google.com/http://www.labs.google.com/http://www.quora.com/http://www.quora.com/http://www.labs.google.com/http://www.reader.google.com/http://www.wikipedia.com/

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Oxalate Nirbhay.pdf