EXPERIMENT REPORT FILE Final Presence of Amount of Oxalate Ion

Chemistry Project

Contents

Aim Introduction Theory Requirements Procedure Chemical Equations Observations Calculations Result Precautions BibliographyAimTo study the presence of oxalate ions in guava fruit at different stages of ripening. IntroductionConstituents % Amount

Water76.10

Proteins1.50

Fats0.20

Calcium0.01

Phosphorus0.04

Vitamin C0.03

Organic Matter14.5

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.

Requirements100 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.

Chemical EquationsMolecular equations:

Ionic equations:

Observations

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 fromBurette ReadingsInitialFinal

Con. Vol. of N/20 KMnO4

Fresh Guavaml.

1 day Guavaml.

2 day Guavaml.

3 day Guavaml.

Concordant volume: (X) _____ml.

CalculationsFor 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 extract2.) 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 extract3.) 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 extract4.) 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!!!

Precautionsa. There should be no parallax while taking measurements.b. Spillage of chemicals should be checked.c. Avoid the use of burette having a rubber tap as KMnO4 attacks rubber.d. 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.e. Add about an equal volume of dil.H2SO4 to the guava extract to be titrated (say a full test tube) before adding KMnO4.f. Read the upper meniscus while taking burette reading with KMnO4 solution.g. In case, on addition of KMnO4, 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.Bibliography Search Engines Used: 1.www.reader.google.com 2.www.quora.com 3.www.wikipedia.org 4.www.google.com 5.www.labs.google.com Practical Chemistry by Laxmi Publications The Family Encyclopedia by Dorling Kindersley Pradeeps Chemistry NCERT Chemistry Chemistry Today Britannica Encyclopedia