PM SHRI SCHOOL JAWAHAR NAVODAYA VIDYALAYA
VENNELA VALASA , SRIKAKULAM
CHEMISTRY INVESTIGATORY
PROJECT
PRESENCE OF OXALATE ION IN GUAVA FRUIT AT
DIFFERENT STAGES OF RIPENING
GUIDED BY:
SHRI A.MALLIKARJUNA RAO
PGT CHEMISTRY
DONE BY :
K.GOVINDA RAO
CLASS XII
ROLL NO: 09
ACKNOWLEDGEMENT
I wish to express my deep gratitude and sincere thanks to the
principal, SHRI D. PARASURAMAIAH , for his encouragement and for a
the facilities that he provided for this project work. I extend my hear
thanks to SHRI A. MALLIKARJUNA RAO teacher who guided me
towards the successful completion of the project. I take this
opportunity to express my deep sense of gratitude for his valuable
guidance, constant encouragement, immense motivation, which has
sustained my efforts at all stages of this project work. I cannot forge
to offer my sincere thanks to my classmates who help me to carry ou
this project work successfully end for there valuable advice and
support, which I received from them time to time...
CERTIFICATE:This is to certify that KUNIBILLI GOVINDA RAO
student of class XII has successfully completed the
investigatory project work titled TO STUDY THE
PRESENCE OF OXALATE ION IN GUAVA FRUIT AT
DIFFERENT STAGES OF RIPENING under the
guidance of A.MALLIKARJUNA RAO, PGT
(CHEMISTRY) during the academic year
2025-2026
Signature of external examiner
Signature of internal examiner
Signature of principal
OBJECTIVE : The presence of oxalate ion content in
guava fruit at stages of ripening
MATERIALS REQUIRED:
Measuring flask, pestle and mortar, beaker, titration flask,
tunnel, burette, weight box, filter paper, Dil.H2SO4, 0.05
KMnO4 solution, guava fruit at different stages of ripening.
THEORY:
Oxalate ions are extracted from the fruit by boiling the fruit
pulp with Dil.H2SO4. Then oxalate ions are estimated
volumetrically by titrating the solution with standard KMnO4
solution.
PROCEDURE:
i. Take only one fully riped guava and peel of its skin weight
25g of this.
ii. Make very small pieces of this with the help of knife, crush it
with the help of pestle and mortar.
iii. Transfer the pulp into 250ml beaker and wash pestle and
mortar with 100ml of distilled water, boil the content for 10
minutes. Cool and filter.
iv. Collect the filtrate into 250ml measuring flask. Make the
volume up to the mark by adding water.
v. Now, pipette out 20ml of this solution from measuring flask and add 20ml
Dil.H2SO4. Heat this 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.
vi. Repeat the above experiment with 25g of 1, 2, 3 days old
guava.
Observation:
Weight of the guava fruit for each time was 50 g.
•Volume of guava extract taken for each titration was 20ml.
N.ormality of KMnO4 solution was (1/10).
t
Guava
Solution
Raw
Semi
Ripened
Ripened
Burette
reading
initial
Final Volume of Concurrent
KMno
4
Reading
Reading
150
150
150
18
137
136.06
13 139.2
10.8
Calculations:
1> For raw guava
N 1 V1 = N2 V 2
132
___>N 1 x 10= (1/10) x 32
____
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
-1
=0.581 g L
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
=0.603g 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
Conclusion :
The strength of oxalate decreases as the guava fruit ripes
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