VEDIC INTERNATIONAL SCHOOL
SESSION- 2024-2025
A Chemistry project on
Study of the presence of oxalate ions in guava fruit at
different stages of ripening.
Submitted by: Under the guidance of:
Name- Rameswar Purohit Mr. Sachin Kumar Giri
Class- XII, Science Mr. Shailendra Kumar
Section- A1 Miss Niharika Sathpathy
Roll No-
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CERTIFICATE
This is to clarify that Rameswar Purohit
student of class XII (Sci.) has successfully
prepared the report on the project entitled
“TOPIC” under the guidance of Miss Niharika
Satapathy (PGT Chemistry).
The report is the result of her efforts &
endeavours. The report is found worthy of
acceptance as final project report for subject
Chemistry of class-XII (Sci.).
Signature of Chemistry teacher Signature of external examiner
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DECLARATION
I hereby declare that the investigatory project work
entitled Topic- Study has been carried out by own
efforts and fact arrived at my observation under the
guidance & motivation of subject teacher MR. Sachin
Kumar Giri, MR. Sailendra Kumar & Niharika
Satapathy.
Rameswar Purohit
XII Science
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ACKNOWLEDGEMENT
The success and final outcome of this project
required guidance and assistance from many people and I
am extremely fortunate to have got all along the
completion of my project work.
I respect Mr. Sachin Kumar Giri sir, for giving me
opportunity to do this project work and providing us all
support and guidance which made me complete the project
on time. I would like to express my gratitude towards our
teacher Preet sir for helping me in conducting practical for
project.
Last but not the least I would like to thank all my
friends who supported me all the way and my parents who
helped me financially and encouraged me throughout in the
completion of project.
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AIM
To study the presence of oxalate ions in
guava fruit at different stages of ripening.
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INTRODUCTION
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Guava, a tropical fruit popular in India and worldwide,
belongs to the Myrtle family (Myrtaceae) and the genus Psidium,
encompassing around 100 species of tropical shrubs and small
trees. Known for its sweet flavour and high vitamin C content,
guava is also a rich source of oxalate ions, which are organic
compounds of interest due to their potential impact on health,
particularly in relation to kidney stones.
As guavas ripen, they undergo significant changes in
colour, texture, and chemical composition. Initially green and
firm, the fruit softens and turns yellow when fully ripe. During
this ripening process, the concentration of oxalate ions within the
fruit varies, influencing its nutritional profile.
Additionally, guavas are recognized for their distinctive
aroma, similar to lemon rind but less intense, adding to their
appeal. This project aims to study the presence and variation of
oxalate ions in guava fruits at different stages of ripening.
What is Oxalate?
It is a carboxylic acid, primarily found in plants and animals. It is
not an essential molecule and is excreted from our body,
unchanged.
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Our body either produces oxalate on its own or converts
other molecules like Vitamin C to oxalate. External sources
like food also contribute to the accumulation of oxalate in
our body. The oxalate present in the body is excreted in the
form of urine as waste. Too much of oxalate in our urine
results in a medical condition called hyperoxaluria,
commonly referred to as kidney stones. Diet is looked upon
as a preventive measure in addition to medication to treat
kidney stones.
THEORY
Oxalate ions are extracted from the fruit by boiling the pulp
with dilute H2S04. The extracted oxalate ions are then
measured volumetrically through titration with a KMn04
solution. In this process, a reagent known as the titrant,
which has a known concentration (standard solution) and
volume, is used to react with the solution containing the
analyte or titrand, whose concentration is unknown. By
using a calibrated burette or a chemistry pipetting synge to
add the titrant, the exact amount consumed can be
determined when the endpoint is reached. The endpoint,
identified by an indicator, marks the completion of the
titration and ideally coincides with the equivalence point.
The equivalence point is where the number of moles of
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titrant equals the number of moles of analyte or a multiple
thereof, as seen in polyprotic acids. In a typical strong acid-
strong base titration, the endpoint is reached when the pH of the
reactant is close to 7, often indicated by a persistent colour
change, such as the pink hue of phenolphthalein indicator.
MATERIAL REQUIRED
APPARATUS
100ML Measuring flask
Beaker
Burette
Funnel
Weighing machine
Fitter Paper
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Chemicals
Dil. H2SO4
N/10 KMnO4 Solution
Guava fruit at different stages of ripening
PROCEDURE
1. Take three fresh pieces of guava of small size. Number these as l, 2,
and 3, keep these at room temperature.
2. Take 50g of guava from piece and crush it into fine pulp using pestle
and mortar.
3. Transfer the crushed guava to a beaker and add 50 ml dil. H2S04.
Boil the contents for 10 minutes
4. Cool and filter the contents in a 100 ml measuring flask. Make up
the volume up to the mark by adding distilled water
5. Fill the burette with standard KMnO4 solution.
6. Note down the initial reading of KMnO4 solution in the burette.
7. Pipette out 20ml of this solution into a conical flask / titration and
add 20ml of dil. Sulfuric acid to it. Heat it to 60-70 oc.
8. Add KMno4 solution from the brute into Titration flask slowly till
permanent light pink colour is obtained. Note the reading of upper
meniscus in the burette.
9. Repeat steps 6, 7, 8—3-4 times so as to get concordant readings.
10. Repeat steps 2-9 with guava sample 2 after I day and with guava
sample 3 after 2 days.
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CHEMICAL EQUATIONS
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OBSERVATION
Weight of the guava fruit for each time was 50 g.
Volume of guava extract taken for each titration was 20 ml
Normality of KMno4 solution was 1/10
End point : colour changes to pink
Burette Burette
Guava Volume of Concurrent
Reading Reading
Solution KMn04 Reading
(Initial) (Final)
Raw 150 18 132
Semi-
150 13 137 136.06
ripened
Ripened 150 10.8 139.2
'
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CALCULATION
CALCULATION
1. For raw guava
N1 V1 = N2 V2
N1 * 10= 1/10 * (X)
Normality of Oxalate , N1 = x/100
Strength of oxalate in fresh guava extract
= normality * Eq. mass of oxalate ion
= 1.32/100 * 44 g/ litre of diluted extract
= 0.581 g/L
2. For semi- ripening guava (1 day old)
Strength of oxalate in one day old guava extract
= 1.37/100 * 44 g/L of diluted extract
= 0.603 g/L
3. For ripening guava
Strength of oxalate in ripening guava extract
= 1.39/100 * 44g/L of diluted extract
= 0.612g/L
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RESULT
a) The normality of oxalate ions of;
Fresh guava solution is = 1.32 ml
Semi-ripen guava solution is =1.37ml
Ripened guava solution is = 1.39 ml
b) The strength of oxalate ions of;
Fresh guava solution is = 0.58 ml
Semi- ripened guava is = 60.0 ml
Ripened guava is = 61.0 ml
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CONCLUSION
The investigation successfully determined the presence
and variation of oxalate ions in guava fruit at different stages
of ripening. The experimental results revealed that the content
of oxalate ions increases as the guava ripens. The strength of
oxalate ions was found to be 0.581 g/L in raw guava, 0.603
g/L in semi-ripened guava, and 0.612 g/L in fully ripened
guava. This trend indicates a clear increase in oxalate
concentration as the fruit matures.
The normality of oxalate ions also showed a gradual
increase from 1.32 ml in raw guava to 1.39 ml in ripened
guava. This aligns with the hypothesis that oxalate content
changes during the ripening process.
The content of oxalate ions in guava was found to be
59.67%, which is close to the literature value of 60%. This
further validates the accuracy of the experimental procedure.
It is evident from the study that the content of oxalate ions
increases as the guava ripens, making the fruit's ripeness a
critical factor in its oxalate concentration.
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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 KMn04
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. 1-12S04 to the guava
extract to be titrated (say a full test tube) before adding
KMn04
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.
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REFERANCES
www. YouTube. Com
www.google. com
www. Wikipedia.com
https:// studylib.net/
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