Oxalate Nirbhay.pdf

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. m e. I could bring it out successfully and so I am thankful to many people.

I would also like to thank my m y friends and family, for supporting me morally. Last but not the least, I would like to thank m my y 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 I could complete my investigator project pr oject 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 Public School and Colleage,session 2013-14 has satisfactorily completed his chemistry project on “ Study of presence of Oxalate ion in guava fruit at different stages of ripening” ripening ” as per the syllabus under my guidance.

Chemistry Teacher Mr. Chanchal Singh (PGT-Chemistry)

External Examiner’s

Signature

CONTENTS    2    e    g    a    P

Introduction

Benefits And Uses of Guava Properties / 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

Procedure Observations Calculations Conclusion Precautions Bibliography

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To study the presence of Oxalate ions in Guava fruit 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 colored with 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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1. Guavas are an excellent source of vitamin C and alsocontain iron calcium, and phosphorus. The guava fruitcontains the highest vitamin C content out of all the citrus 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 and bronchitis.    6    e    g    a    P

4. The roots, bark, leaves and immature fruits, because of their astringency, are commonly employed to haltgastroenteritis, diarrhea, dysentery and vomiting in cholera patients. 5. It also has hypoglycemic and anti bacterial properties.The fruit, when eaten whole helps reduce both, high blood pressure and cholesterol levels. 6. Guava benefits in battling diabetes, combats cancer and protects prostate. 7. Guava can improve heart health by helping to control blood pressure and cholesterol. 8. Guava is highly effective in removing constipation.

PROPERTIES / ACTIONS DOCUMENTED BY RESEARCH Guava fruit acts as a

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Amebicide, analgesic (pain reliever), antibacterial, anticandidal, antidysenteric, antifungal, antimalarial, antioxidant, antispasmodic, antiulcerous, cardio depressant, cardiotonic (tones, balances, strengthens the heart), central nervous system depressant, cough suppressant, gastrototonic (tones, balances, strengthens the gastric tract), hypotensive (lowers blood pressure), sedative, vasoconstrictor).

Other Properties/Actions Documented by Traditional Use Guava 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:

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1. Guava has recently demonstrated cardiac depressant activity and should be used with caution by those on heart medications.

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 the 2 2 formula C2O4 −, also written (COO) 2 −. Either name is often used for derivatives, such as salts of oxalic acid (for 2 example sodium oxalate, ((Na+)2C 2O4 −) or esters thereof (for example dimethyl oxalate, ((CH3) 2C2O4). Oxalate also forms coordination compounds where it is sometimes abbreviated as ox. Oxalate is an organic acid, primarily found in plants, animals and humans. It is not an essential molecule and is excreted from our body in an unchanged form. Our body either produces oxalate on its own or it converts other molecules like vitamin C to oxalate.External sources like the foods we eat also contribute to the accumulation of oxalate in our body. The oxalate present in the body is excreted in our urine as a waste. Too much of oxalate in our urine,results in a medical condition called as hyperoxaluria, 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

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X-ray crystallography of simple oxalate salts show that the oxalate anion may adopt either a planar conformation with D2h molecular symmetry, or a conformation where the OC-C-O dihedrals approach 90° with approximate D 2d symmetry.Specifically, the oxalate moiety adopts the planar, D2h conformation in the solid-state structures of M2C2O4 (M = Li, Na, K).However, in structure of Cs 2C2O4 the O-C-C-O dihedral angle is 81(1)°. Therefore, Cs2C2O4

is more closely approximated by a D 2d symmetry structure because the two CO 2 planes are staggered. Interestingly, two forms of Rb2C2O4 have been structurally characterized by single-crystal, X-ray diffraction: one contains a planar and the other a staggered oxalate.  As the preceding examples indicate that the conformation adopted by the oxalate dianion is dependent upon the size of the alkali metal to which it is bound, some have explored the barrier to rotation about the central C−C bond. It was determined computationally that barrier to rotation about this bond is roughly 2 –6 kcal/mole for the 2 free dianion, C2O4 −.[6] Such results are consistent with the interpretation that the central carbon-carbon bond is best regarded as a single bond with only minimal pi interactions between the two CO 2 units.This barrier to rotation about the C−C bond (which formally corresponds to the difference in energy between the planar and staggered forms) may be attributed to electrostatic interactions as unfavorable O−O repulsion is maximized in the planar form. It is important to note that oxalate is often encountered as a bidentate, chelating ligand, such as in potassium ferrioxalate. When the oxalate chelates to a single metal center, it always adopts the planar conformation.

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REQUIREMENTS (A)Apparatus  100

ml measuring flask  Pestle  Mortar  Beaker  Titration flask  Funnel  Burette  Weight box  Filter paper (B)Chemicals Required  Dilute

H2SO4  N/20 KMnO4 solution  Guava fruits at different stages of ripening.

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Oxalate ions are extracted from the fruit by boiling pulp with dil.H2SO4.Then oxalate ions are estimated volumetrically by titrating the solution with standard KMnO4 solution.Titration is a common laboratory method of quantitative chemical analysis that is used to determine the unknown concentration of a known reactant. Because volume measurements play a key role in titration, it is also known as volumetric analysis. A reagent, called the titrant or 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 a calibrated burette or chemistry pipetting syringe to add the titrant, it is possible to determine the exact amount that has been consumed when the endpoint is reached. The endpoint is the point at which the titration is complete, as determined by an indicator. This is ideally the same volume as the equivalence point-the volume of added titrant at which the number of moles of titrant is equal to the number of moles of analyte.In the classic strong acidstrong base titration,the endpoint of a titration is the point at which the pH of the reactant is just about equal to 7, and often when the solution takes on a persisting solid colour as in the pink of phenolphthalein indicator.

Redox titration    4    1    e    g    a    P

Redox titration (also called oxidation reduction titration ) is a type of titration based on a redox reaction between the analyte and titrant. It is a titration of a reducing agent by an oxidizing agent between the analyte and titrant. Redox reaction may involve the use of a redox indicator. This experiment involves the use of potassium permanganate which is the oxidizing agent as well as the indicator. Permanganate ion is a powerful oxidizing agent, especially in acidic solution, which can be used to analyze (by titration ) solutions containing many different species. In these titration reactions, the intensely colored MnO 4  ion is reduced to form the colorless Mn +2 ion.  An advantage of using the permanganate ion in the titration of colorless unknown solutions is that it is “self indicating”. As long as the reducing agent remains present in the sample, the color of MnO 4  quickly disappears as it is reduced to +2 Mn . However, at the endpoint, all the reducing agent has been used up so the next drop of MnO 4  solution is sufficient to cause an easily detected color change, colorless (faint, permanent peach / pink ). So we know that -4 at the endpoint, the oxidizing agent (MnO 4 ) and reducing +2 agent (H2O2 or Fe ) have reacted in exactly in proportion to their stoichiometry in the balanced redox equation. If we know how much of the oxidizing agent we added, then we can figure out exactly how much reducing agent was present in the unknown    5    1    e    g    a    P

CHEMICAL EQUATIONS Molecular Equations

2KMnO4 + 3H2SO4  K2SO4+ 2MnSO4+ 2H2O +4[O] {HOOC-COOH.2H2O +[O]

 2CO2+

2H2O } x 5

3KMnO4+ 3H2SO4+5HOOCCOOH.2H2O K2SO4+2MnSO4 +18H2O + 10CO2



Ionic Equations -

+

MnO4 +16H + 5e - 

2+

 Mn

+ 4H2O x 5

-

2C2O4  2CO2+ 2e x 5 -

+

2-

2MnO4 + 16H + 5C2O4

2+

2Mn

+8H2O + 10CO2

PROCEDURE    6    1    e    g    a    P

(1) Weighed 50 g of fresh guava and crushed it to a fine pulp using pestle and mortar. (2) Transferred the crushed pulp to a beaker and added about 50 ml dilute H2SO4 to it. (3) Boiled the content for about 10 minutes. Cooled and filtered the contents in a 100 ml measuring flask. (4) Made up the volume 100 ml by adding ample amount of distilled water. (5) Took 20 ml of the solution from the flask and added 20 ml 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 the end point had an appearance of pink colour. (7) Repeated the above experiment with 50 g of 1day, 2 day and 3 day old guava fruits.

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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 Guava Burette Final Volume of Solution reading Reading KMnO4 Initial Raw 150 18 132 13 137 Semi-ripened 150 Ripened 150 10.8 139.2

Concurrent Reading

136.06

CALCULATIONS 1.For raw guava  N1V1 =

N2V2 N1 x 10 = (1/10) x132 1/10 x Normality of oxalate = (x/100) = strength of oxalate in fresh guava extract = normality x Eq. mass of oxalate ion = 1.32/100 x 44g/litre of diluted extract = 0.581 g L-1    8    1    e    g    a    P

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

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) x 44g/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 be 59.67 per cent, which is close to the literature value of 60 percent. It was also noticed that the content of oxalic ions grows with ripening of guava.

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The content of oxalate ions in guava was found to be 59.67 per cent, which is close to the literature value of 60 percent. It was also noticed that the content of oxalic ions grows with ripening of guava.

PRECAUTIONS 1. KMnO4 solution is always taken in the burette. 2.Avoid the use of burette having a rubber tap as KMnO 4  Attacks rubber. 3.In order to get some idea about the temperature of the solution touch the flask to the back side of your hand. When it becomes unbearable to touch, the required temperature is reached. 4.Add about an equal volume of dil. H 2SO4 to the guava extract to be titrated (say a full test tube) before adding KMnO 4.

5.Read the upper meniscus while taking burette reading with KMnO4 solution.    0    2    e    g    a    P

6.In case, on addition of KMnO 4 a brown ppt. appears, this shows that either H 2SO4 has not been added or has been

added in insufficient amount. In such a case, throw away the solution and titrate again. 7.The concentration of oxalate ion obtained from the filtrate is unfavourably high. If the titration is carried with concentrated filtrate, the scale of the burette is out of scope in regard to the concentration of the oxalate ion. So diluting the concentrated filtrate to an appropriate proportion and titrating it withKMnO 4 and estimating the end point will make it favourable.After estimating the end from the diluted solution, the original concentration of the concentrated filtrate can be calculated by multiplying the concentration the estimated filtrate with the factor by which it was diluted.

Bibliography    1    2    e    g    a    P

1.Search engines used: 

www.google.com



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.

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