CHEMISTRY INVESTIGATORY
PROJECT
TOPIC:
STUDY OF OXALATE ION IN
GUAVA FRUIT
BY: SUNIL.
1
INTRODUCTION:
Guava (/ˈɡwɑːvə/)is a common tropical
fruit cultivated in many tropical and subtropical regions. The common
guava Psidium guajava (lemon guava, apple guava) is a small tree in the
myrtle family (Myrtaceae), native to Mexico, Central America,
the Caribbean and northern South America.[2] The name guava is also
given to some other species in the genus Psidium such as strawberry
guava (Psidium cattley Anum) and to the pineapple guava, Feijoa
sellowiana. In 2019, 55 million tonnes of guavas were produced
worldwide, led by India with 45% of the total. Botanically, guavas
are berries.
Scientific Name: Psidium Guajava
Common Name: Guava
Family: Myrtaceae
Parts Used: Fruits, seeds, and
leaves
Guava Health Benefits:
Aids weight loss
May relieve constipation
may treat colds and cough
Helps with a toothache
Promotes healthy skin
May prevent diabetes
Maintains blood pressure
May prevent cancer
Promotes a healthy cardiovascular system
Guava contains 21% vitamin A that helps brighten up your skin
and maintains mucous membranes.
This fruit also contains 20% folate that works well for pregnant
women and prevents neural tube damage.
Lycopene, found in pink coloured guavas are good for protecting
skin against ultraviolet rays (UV) and also prevents prostate
cancer.
Health Benefits of Guava:
Guava fruits are called the queen of all fruits because of their high level
of medicinal value. Any 100 grams serving of guava fruit contains 68
calories and 8.92 grams of sugar. It is also rich in calcium and contains
18 grams of minerals for every 100 grams. This shows that the fruit has
the capability to aid in different diseases. However, in order for you to
have more insight into the topic, let’s take a peek into the health benefits
of guava.
Guava helps boost your immunity
Guava is rich in vitamin C and is said to contain four times the content of
vitamin C found in oranges. Vitamin C helps boost immunity levels that
prepare your body to fight common infections and pathogens. Also, more
vitamin C helps in good eyesight.
May reduce the risk of developing Cancer
Vitamin C, lycopene and other types of polyphenols act as antioxidants
that help in neutralising infections in the body that prevent the growth of
cancerous cells. Guava fruit has been shown to prevent prostate
cancer and also prevents the growth of breast cancer cells.
Helps to manage blood sugar levels
Guava has a high content of fibre and glycaemic index that helps prevent
the development of diabetes. You may refer to Glycemic Index Food
Chart to find out the GIs of other foods and modify your diet
accordingly. Fibre content regulates blood sugar levels from spiking,
while glycemic index also restricts your blood sugar to rise at a short.
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May help with menstruation pain
Many women experience bad and painful cramps as period symptoms.
There is a study that suggests guava leaf extract can help reduce the pain
during menstruation. This study involved 197 women consuming the
guava leaf extract (6 mg) and found that it greatly helped in reducing the
pain and that it works better than many painkillers as well!
Guava helps women during pregnancy
Guavas benefit pregnant women such that it contains folic acid and
vitamin B-9 which is recommended to be given for women since it
helps in developing the baby’s nervous system and protects the baby
from neurological disorders.
OXALATE ION IN GUAVA FRUIT:
What is Oxalate?
2- 2-
Oxalate is the dianion with the formula C2O4 also written as (COO) .
either name is often used for derivation, such
2-
as salts of oxalic acid for example, sodium oxalate 2[(Na)+2C2O4 ] or
esters. For example, Dimethyl oxalate
((CH3)2C2O4 also forms coordination compounds where it is
abbreviated as ox. Many metal ions from insoluble
precipitates with oxalate.
The Formula for Oxalates:
(C2O4)−2
It is also called Ethanedioate or Oxalate Ion. One can obtain it by
deprotonation of both the carboxyl groups of C2H2O4 i.e., oxalic acids. It
is mainly useful for the derivatives, such as salts of oxalic acid.
Oxalate Content in Guava Fruit:
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.
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Relationship to oxalic acid
The dissociation of protons from oxalic acid proceeds in a stepwise
manner; as for other polyprotic acids, loss of a single proton results in the
monovalent hydrogen oxalate anion HC2O−4.
A salt with this anion is sometimes called an acid oxalate, monobasic
oxalate, or hydrogen oxalate. The equilibrium constant (Ka) for loss of the
first proton is 5.37×10−2 (pKa = 1.27). The loss of the second proton,
which yields the oxalate ion, has an equilibrium constant
of 5.25×10−5 (pKa = 4.28). These values imply, in solutions with
neutral pH, no oxalic acid and only trace amounts of hydrogen oxalate
exist.
Uses of Oxalate:
Although natural Oxalates are harmful to the human body, artificially
made oxalates are useful to mankind in many ways.
Calcium Oxalate is used in the production of ceramic materials,
Barium Oxalate and Strontium Oxalate are used as reducing agents
in laboratory chemistry and pyrotechnics.
Potassium hydrogen-Oxalate, also known as salt of sorrel, is used
as chemical reagents due to its occurrence in the sorrel plant. It is
also used in photography and for the removal of ink stains.
Ferric Oxalate is a chemical compound used in platinum
printmaking,
Cobalt Oxalate is used in the production of cobalt catalysts.
Oxalates may also be used in some instances as sources of the
metals they contain.
ABSTRACT:
The Aim of this project is to determine the concentration
of oxalate ion present in guava fruit. The oxalate content
of guava fruit at different stages of ripening were found
out by permanganometric method. Oxalate rich foods are
usually restricted to some degree, particularly in patients
with high urinary oxalate level. Guava have the highest
percentage of vitamin C among citrus fruits. It also
contains oxalate amount of which varies with ripening of
the fruit. During ripening of guava fruit; the oxalate
content increases progressively and the fully ripe fruit
has the maximum oxalate content. Further investigations are
warranted to explore the implications of consuming guava fruit
on oxalate-related health concerns.
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EXPERIMENT
AIM: To study the presence of oxalate ion in guava
fruit at different stages of ripening.
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 titrant, 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.
Constituent % Amount
Water 76.10
Protein 1.50
Fats 0.20
Calcium 0.01
Phosphorus 0.04
Vitamin C 0.03
Organic matter 14.50
APPARATUS REQUIRED:
1. 100ml measuring flask
2. Pestle & mortar
3. Beaker Funnel
4. Filter paper
5. Weighing machine
Chemicals:
6.dil H2SO4
7.KMnO4 solution
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Guava fruit at different stage of ripening:
CHEMICAL EQUATIONS:
2KMnO4 + 3H2SO4 → K2SO4 + 2MnSO4 + 2H2O + 4[O] HOOC -
COOH.2H2O + [O] → 2CO2 + 2H2O x 5
2KMnO4 + 3H2SO4 + 5HOOC-COOH.2H2O → K2SO4 + 2MnSO4 +
18H2O + 10CO2
IONIC EQUATIONS:
MnO4 - + 16H+ + 5e- → Mn2+ + 4H2O x 2 C2O4 2-→ 2CO2 + 2e- x 5
2MnO4 - + 16H+ + 5C2O4 2- → 2Mn2+ + 8H2O + 10CO2
PROCEDURES:
Weighed 50 g of fresh guava and crushed it to a fine pulp using
pestle and mortar.
Transferred the crushed pulp to a beaker and added about 50 ml
dilute H2SO4 to it.
Boiled the content for about 10 minutes. Cooled and filtered the
contents in a 100 ml measuring flask.
Made up the volume 100 ml by adding ample amount of distilled
water.
Took 20 ml of the solution from the flask and added 20 ml of dilute
sulphuric acid to it.
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.
Repeated the above experiment with 50 g of 1 day, 2 day and 3-day
old guava fruits.
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PRECAUTIONS:
There should be no parallax while taking measurements.
Spillage of chemicals should be checked.
Avoid the use of burette having a rubber tap as KMnO4 attacks
rubber.
In order 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.
Add about an equal volume of dil H2SO4 to the guava extract to
be titrated (say a full test tube) before adding KMnO4 .
Read the upper meniscus while taking burette reading with
KMnO4 solution
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.
OBSERVATIONS:
Weight of the guava fruit for each time was 50 g.
Volume of guava extract taken for each titration was 10 ml.
Normality of KMnO4 solution was (1 / 10).
End point: Colour changes to pink
GUAVA Burette Final Volume of Concordant
SOLUTION
reading Reading KMnO4 Reading
initial
Raw 150 18 132
Semi Ripened 150 13 137 136.06
Ripened 150 10.8 139.2
CALCULATIONS:
1. For Raw Guava:
N1V1 = N2V2
N1 x 10 = (1 / 10) x 132
N1 = 132 /100 = 1.32
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Strength of oxalate in fresh guava extract = normality x Eq. mass of
oxalate ion = 1.32 /100 x 44g / litre of diluted extract = 0.581g L-1
2. For Semi-Ripen Guava:
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 ripened guava extract = 1.39 /100 x 44g / litre
of diluted extract = 0.612 g L-1
RESULT:
a) The Normality of Oxalate Ion of:
Fresh guava solution is = 1.32 N
Semi - ripen guava solution is = 1.37 N
Ripened guava solution is = 1.39 N
b) The Strength of Oxalate Ion of:
Fresh guava solution is = 0.58 gL-1
Semi - ripen guava solution is = 0.60 gL-1
Ripened guava solution is = 0.61 gL-1
CONCLUSION:
The content of oxalate ion in guava was found to be 59.67 percent,
which is close to the literature value of 60 percent.
It was also noticed that the content of oxalate ion grows with
ripening of guava.
Bibliography:
http://greenparkschool.co.in/greenpark/index.php/blog/chemistry/PRESENCE%20OF
%20OXALATIVE%20IONS%20IN%20GUAVA.pdf
https://en.wikipedia.org/wiki/Guava
https://www.botanichealthcare.net/psidium-guajava/
https://www.scribd.com/document/618691026/Presence-of-Oxalate-Ions-in-Guava-Chemis-
2
https://www.google.com/search?
q=ripe+guava&tbm=isch&rlz=1C1CHBF_enIN914IN914&hl=en-
GB&sa=X&ved=2ahUKEwjH067kupD_AhUAzqACHSunDi4QBXoECAEQYw&biw=1404&bih=68
4
https://pharmeasy.in/blog/guava-fruit-benefits-amazing-uses-of-guava-leaves/
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