ixolate ion

Index
Acknowledgement
Introduction & Objective
Theory
Requirements
Procedure
Observation & Calculation
Result

Acknowledgement

I __________ of class _______ thereby declare that this investigatory project of chemistry on “Study of presence of Oxalate Ion content in Guava fruit at different stages of ripening” is made by my own hard work and efforts under the supervision of our Chemistry Teacher__________________
Signature:___________________

Introduction & Objective

Guava is a sweet, juicy and light dark green coloured fruit, when ripe it acquires a yellow colour & has a penetrating strong scent. The fruit is rich in vitamin C & minerals. It is a rich source of oxalate and its content in the fruit varies during different stages of ripening. In this project, we will learn to test for the presence of oxalate ions in the guava fruit and how it amount varies during 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 dilution with standard KMnO4 solution. fig:- Oxalate Ion
Requirements: -
100 ml. Measuring flask, pestle & mortar, beaker, titration flask, funnel, burette, weight-box, pipette, filter paper, dilute H2SO4, N/20 KMnO4 solution, guava fruits at different stages of ripening.

PROCEDURE
1.) Weigh 50.0 g of fresh guava & crush it to a fine pulp using pestle-mortar.
2.) Transfer the crushed pulp to a beaker & add about 50 ml. dil. H2SO4 to it. Boil the contents for about 2 minutes.
3.) Cool & filter the contents in a 100 ml. measuring flask. Make the volume up to 100 ml. by adding distilled water.
4.) Take 20 ml. of the solution from the measuring flask into a titration flask& add 20 ml. of dil.H2SO4 to it. Heat the mixture to about 60oC & titrate it against N/20 KMnO4 solution taken in a burette.
5.) END POINT: appearance of permanent Light-Pink colour.
6.) Repeat the exp. With 50.0 g of 1, 2 & 3 days old guava fruit.

Observations & Calculations

Weight of Guava Fruit taken:- 50.0 g
Volume of guava extract in titration:- 20.0 ml
Normality of KMnO4 Solution:- 1/20
Guava extract from
Burette Readings
Initial
Final

Con. Vol. of N/20 KMnO4
Fresh Guava

ml.
1 day Guava

ml.
2 day Guava

ml.
3 day Guava

ml.
Concordant volume: (X) _____ml.
For fresh Guava,
(guava extract) N1V1 = N2V2 (KMnO4 sol.) N1 X 10 = 1/20 x (X)

Normality of Oxalate, N1 = (X)/200

1.) Strength of Oxalate in Fresh guava extract, = Normality x Eq. mass of oxalate ion = (X)/200 x 44 = /200 x 44 = _____ g/l. of the diluted extract
2.) Strength of Oxalate in 1 Day guava extract, = Normality x Eq. mass of oxalate ion = (X)/200 x 44 = /200 x 44 = _____ g/l. of the diluted extract
3.) Strength of Oxalate in 2 Day guava extract, = Normality x Eq. mass of oxalate ion = (X)/200 x 44 = /200 x 44 = _____ g/l. of the diluted extract
4.) Strength of Oxalate in 3 Day guava extract, = Normality x Eq. mass of oxalate ion = (X)/200 x 44 = /200 x 44 = _____ g/l. of the diluted extract
Result

Strength of Oxalate ion in,
Fresh Guava: _____g/l.
1 Day Guava: _____g/l.
2 Day Guava: _____g/l.
3 Day Guava: _____g/l.
Presence of oxalate ion is high in guava, about ____% of guava contains oxalate ions, amount of oxalate ion decreases as it ripens!!!