Study of presence of

Oxalate ions
In

Guava Fruit
At different stages of ripening

Made By:
JIGNESH
GURJAR
XII Sci B
 CERTIFICATE
This is certified to be bonafide work of the JIGNESH GURJAR of
Class XII B in the CHEMISTRY LABORATORY during academic
year 2023-2024.

Teacher In-charge

Examiner’s Signature Principal Signature

Date………………
 INDEX

S.No. Topic Page

1. Acknowledgement 4
2. Introduction 5
3. Plant Chemicals 6
4. Oxalic Acid 8
5. Experiment 9
6. Observations 11
7. Calculations 12
8. Conclusion 13
9. Bibliography 14
 ACKNOWLEDGEMENT
I would like to express my sincere gratitude to Mr. Vikash Upadhyay
for the valuable guidance and help
provided by her for undertaking and completing this project.

I would also like to thank my PARENTS for providing me the material

and help in completing this project.
 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-colored bark that flakes off, showing a greenish
layer beneath.

Guava fruit today is considered minor in terms of commercial world

trade but is widely grown in the tropics, enriching the diet of
hundreds of millions of people in the tropics of the world. Guava
has spread widely throughout the tropics because it thrives in a
variety of soils, propagates easily, and bears fruit relatively quickly.
The fruits contain numerous seeds that can produce a mature fruit-
bearing plant within four years.
 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 antidiarrhea effect of
guava; it is able to 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, alphahumulene,

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, Dgalactose, 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 D, 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.
GUAVA PLANT SUMMARY
Main Preparation Method: decoction

Main Actions (in order):

antidysenteric, antiseptic, antibacterial, antispasmodic,
cardiotonic (tones, balances, strengthens the heart)

Main Uses:

1. for dysentery (bacterial and amebic), diarrhea, colic,

and infantile rotavirus enteritis
2. as a broad-spectrum antimicrobial for internal and
external bacterial, fungal, candidal, and amebic
infections
3. to tone, balance, protect and strengthen the heart (and
for arrhythmia and some heart diseases)
4. as a cough suppressant, analgesic (pain-reliever), and
febrifuge (reduces fever) for colds, flu, sore throat, etc
5. as a topical remedy for ear and eye infections

Properties/Actions Documented by Research:

amebicide, analgesic (pain-reliever), antibacterial,
anticandidal, antidysenteric, antifungal, antimalarial,
antioxidant, antispasmodic, antiulcerous, cardiodepressant,
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:

anti-anxiety, anticonvulsant, antiseptic, astringent, blood
cleanser, digestive stimulant, menstrual stimulant, nervine
(balances/calms nerves), vermifuge (expels worms)

Cautions: It has a cardiac depressant effect and is

contraindicated in some heart conditions.
 OXALIC ACID
Oxalic acid is the chemical compound formula H2C2O4. 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 sour 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. Such
tiny crystals can cause damage to human tissue, especially to the
stomach, the kidneys, and the bladder. It is commonly believed that
oxalates contribute to the formation of kidney and bladder stones;
one common nutrient with which oxalic acid combines is calcium,
making the salt calcium oxalate, and calcium oxalate is found in
kidney stones.
To study the presence of Oxalate
Ion content in Guava Fruit at different stages
of ripening
Requirements:

100 ml measuring flask, pestle and

mortar, beaker, titration flask, funnel,
burette, weight box, pipette, filter
paper, dilute H2SO4, KMnO4, and guava fruits at different stages
of ripening.

Theory:

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.

End Point:

Appearance of permanent pink colour.

Procedure:

1. 50.0g of fresh guava was weighed and crushed to a fine pulp

using pestle-mortar.
2. The crushed pulp was transferred to a beaker and about 50ml
dil. H2SO4 was added. The contents were boiled for about 10
minutes.
3.The contents were filtered and cooled in 100ml measuring
flask. The volume was made up to 100ml by adding distilled
water.
4. 20ml of this solution was taken into a titerating flask and 20ml
of dil. H2SO4 was added to it. The mixture was heated to about
60°C and titerated against the standard KMnO4 solution taken
in a burette
 Observations:
Weight of guava taken = 50.0 g

Volume of guava extract taken = 20.0 ml

Normality of KMnO4 solution =

Guava extract from Burette readings Concordant

volume of
Initial Final
KMnO4
Solution used
Fresh 0 50 50
1 day old 0 30 30
2 day old 0 15 15
3 day old 0 9 9
 CAlCULATION
N1V1 = N2V2
(guava extract) (KMnO4 solution)

N1 x 20 = 1/20 x V
∴ Normality of oxalate, N1 = V/400
Strength of oxalate = Normality x Eq. mass of oxalate ion extract
= V/400 x 44 g/litre of the diluted

Guava extract from Strength of oxalate ion (g/litre)

Fresh 5.5
1 day old 3.3
2 day old 1.65
3 day old 0.99
 CONCLUSION
Oxalic acid and oxalates are abundantly present in many plants,
most notably in sour grass, and sorrel (including Oxalis), roots and
leaves of rhubarb and buckwheat.

After doing this experiment we can conclude that unripe guava has
a high content of Oxalate ions. The concentration of oxalate ions
decreases with the ripening of fruit.
 BIBLIOGRAPHY
In order to complete this project, I took help from: My chemistry
teacher
Comprehensive Practical Chemistry (Lab Manual) of
Millinium
Different internet sites:
www.google.com www.rain-tree.com
www.wikipedia.com