Department Of Chemistry

Project Report 2024-2025

To study the presence of oxalate ions in guava fruit

at different stages of ripening

VIVEKANANDA VISION SENIOR SECONDARY

SCHOOL KATCHUR

GUIDED BY

Mr. Anoop George

PGT Chemistry
MSc Chemistry, B.Ed.

DONE BY- KARAN.T

ROLL NO-
 CERTIFICATE

I hereby that is a bona-fide report of project work done

by Karan.T of XII, Vivekananda Vision Senior
Secondary School, Katchur, Tiruvallur District, Tamil
Nadu under my supervision during the academic year
2024-25.

 Place:
Katchur
 Date:
Mr. Anoop P George
PGT Chemistry
MSc Chemistry, B.Ed.

Vivekananda Vision Senior Secondary School, Katchur

This is to certify that, karan.t roll. No. has

submitted this project for project for practical examination
of
SSCE 2024-25

SIGNATURE OF

PRINCIPAL: INTERNAL

EXAMINER: EXAMINER IN

CHARGE:
 ACKNOWLEDGEMENT

This is to acknowledge that this investigatory project

would not have been successful without the help of the
source that are mentioned below.
project so at the onset a very great thanks to our
respected subject teacher Mr. Anoop George (PGT
CHEMISTRY) without his guidance this investigatory
project would not have been possible. Lastly, I would
like to thank our parents who really helped us in each
and every movement, friends and everyone who is
directly or indirectly associated with the completion of
this investigatory project of chemistry.

DONE BY- KARAN.T

 INDEX

 ACKNOWLEDGEMENT
 INTRODUCTION
 PLANT CHEMICALS
 OXALIC ACID
 THEORY
 EXPERIMENT
1) REQUIREMENTS
2) PROCEDURE
3) PRECAUTIONS
4) OBSERVATIONS
5) CALCULATIONS
6) CONCLUSIONS
 INTRODUCTION

Family: Myrtaceae
Genus: Psidium
Species: guajava
Common names: Guava, goiaba,
guayaba, djamboe, djambu,
goavier, gouyave, goyave, goyavier, perala, bayawas,
dipajaya jambu, petokal, tokal, guave, guavenbaum,
guayave, banjiro, goiabeiro, guayabo, guyaba,
goeajaaba, guave, goejaba,
kuawa, abas, jambu batu, bayabas, pichi, posh, enandi
Part Used: Fruit, leaf, bark.
Guava is a common shade tree or shrub in dooryard
gardens in the tropics. It provides shade while the guava
fruits are eaten fresh and made into drinks, ice cream,
and preserves. In the richness of the Amazon, guava
fruits often grow well beyond the size of tennis balls on
well-branched trees or shrubs reaching up to 20 m high.
Cultivated varieties average about 10 meters in height
and produce lemon-sized fruits. The tree is easily
identified by its distinctive thin, smooth, copper-
coloured bark that flakes off, showing a greenish layer
beneath.

PLANT CHEMICALS
Guava is rich in tannins, phenols, triterpenes,
flavonoids, essential oils, saponins, carotenoids, lectins,
vitamins, Fiber and fatty acids. Guava fruit is higher in
vitamin C than citrus (80 mg of vitamin C in 100 g of
fruit) and contains appreciable amounts of vitamin A as
well. Guava fruits are also a good source of pectin- a
dietary Fiber. The leaves of guava are rich in
flavonoids, in particular, quercetin. Much of guava's
therapeutic activity is attributed to these flavonoids.
The flavonoids have demonstrated antibacterial activity.
Quercetin is thought to contribute to the anti-diarrhoea
effect of guava; it can relax intestinal smooth muscle
and inhibit bowel contractions. In addition, other
flavonoids and triterpenes in guava leaves show
antispasmodic activity. Guava also has antioxidant
properties, which is attributed to the polyphenols found
in the leaves.
Guava's main plant chemicals include: alanine, alpha-
humulene, alpha-hydroxyursolic acid, alpha-linolenic
acid, alpha-selinene, amritoside, araban, arabinose,
arabopyranosides, arjunolic acid, aromadendrene,
ascorbic acid, ascorbigen, asiatic acid, aspartic acid,
avicularin, benzaldehyde, butanal, carotenoids,
caryophyllene, catechol- tannins, crataegolic acid, D-
galactose, D-galacturonic acid, ellagic acid, ethyl
octanoate, essential oils, flavonoids, gallic acid,
glutamic acid, goreishic acid, guafine, guavacoumaric
acid, guaijavarin, guajiverine, guajivolic acid,
guajavolide, guavenoic acid, guajavanoic acid,
histidine, hyperin, ilelatifol isoneriucoumaric acid,
isoquercetin, jacoumaric acid, lectins, leucocyanidins,
limonene, linoleic acid, linolenic acid, lysine,
mecocyanin, myricetin, myristic acid, nerolidiol,
obtusinin, octanol, oleanolic acid, oleic acid, oxalic
acid, palmitic acid, palmitoleic acid, pectin,
polyphenols, psidiolic acid, quercetin, quercitrin, serine,
sesquiguavene, tannins, terpenes, and ursolic acid.

What is oxalate?
It is a carboxylic acid, it is not an essential molecule
and is excreted from our body, unchanged. Our body
either produces oxalate on its own or converts other
molecules like Vitamin C to oxalate.

OXALIC ACID

It is the chemical compound formula H:C₂O. This

dicarboxylic acid is better described with the formula
HO₂CCO₂H. It is a relatively strong organic acid,
being about 10,000 times stronger than acetic acid. The
dianion, known as oxalate, is also a reducing agent and
a ligand in coordination chemistry. Oxalic acid and
oxalates are abundantly present in many plants, most
notably in souw grass, and sorrel (including Oxalis),
roots and leaves of rhubarb and buckwheat.
At high concentrations, it is a dangerous poison, but
such immediately toxic levels are not found in
foodstuffs but rather in manufactures, such as some
bleaches, some anti-rust products, and some metal
cleaners (among other things). It is also a naturally
occurring component of plants and is found in relatively
high levels in dark-green leafy foods In the human
body, ingested oxalic acid is not a useful nutrient; so,
like all such unneeded components of diet, it is
processed by the body to a convenient form and that
byproduct is then excreted-- in this case, in the urine. In
the course of being processed by the body, oxalic acid
combines with other substances to form various salts,
called oxalates; usually, those salts are in solution, but
in high concentration some may precipitate out in
crystalline form. Suck tiny crystals can cause damage to
Auman tissue, especially to the stomach, the kidneys,
and the bladder. It is commonly believed that oxalates
contribute to the formation of kidney and Gladder
stones; one common nutrient with which oxalic acid
combines is calcium, making the salt calcium oxalate,
and calcium oxalate is found in kidney stone.
 THEORY
Oxalate ions are extracted from the fruit by boiling pulp
with dilute H2SO4.The oxalate ions are estimated
volumetrically, by titrating the solution with KMnO4
solution.

A reagent, called the titrant, 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.

REQUIREMENT

(A) Apparatus
100 ml measuring flask,Pestle &
Mortar,Beaker,Funnel,Burette,Weighning
machine,Filter Papers.

(B) Chemicals
Dil. H2SO4, (Ν/10) KMnO4 solution.

(C) Guava fruits at different stages of ripening.

 PROCEDURE
(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 HSO 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 60° 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 1 day,

2 day and 3-day old guava fruits.
 PRECAUTIONS
1. There should be no parallax while taking
measurements.

2. Spillage of chemicals should be checked.

3. Avoid the use of burette having a rubber tap

as KMnO4 attacks rubber.

4. To get some idea about the temperature of the

solution touch the flask with the back side of your hand.
When it becomes unbearable to touch, the required
temperature is reached.

5. Add about an equal volume of dil. H₂SO4 to the

guava extract to be titrated (say a full test tube) before
adding KMnO4

6. Read the upper meniscus while taking burette reading

with KMnO4 solution.
7. In case, on addition of KMnO4, a brown ppt.
appears, this shows that either H2SO4 has not been
added or has been added in insufficient amount. In
such a case, throw away the solution and titrate again.

OBSERVATION

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

 CALCULATION

1) For raw guava

NIV1 = 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
2) For semi ripened guava (1 day old).
Strength of oxalate in one day old guava extract
= (1.37/100) x 449/litre of diluted extract
=0.603 g L-1
3) For ripened guava
Strength of oxalate in fresh guava extract
= (1.39/100) x 449/litre of diluted extract
= 0.612 g L-1
 RESULTS

(a) The normality of oxalate ions of:

(i) Fresh guava solution is = 1.32ml
(ii) Semi-ripen guava solution is =1.37 ml.
(iii) Ripened guava solution is =1.39ml

(b) The strength of oxalate ions of:

(i) Fresh guava solution is = 0.58ml
(ii) Semi-ripened guava is = 0.60ml
(iii) Ripened guava is = 0.61 ml

CONCLUSIONS

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.
 Bibliography

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 Kinders