ACKNOWLEDGEMENT

This project was very innovative and exciting for me. I

could bring it out successfully and so I am thankful to a

couple of people.

First of all I am highly obliged to my Chemistry teacher,

Miss Deepa Jaiswal who approved me for this topic and

guided me throughout.I am also great full to Aadaharshila

School Library for providing me with the necessary books

that I required for the project. I am thankful to Montfort

school laboratory and lab assistant who helped me to

successfully carry out titrations and taught me how to handle

the chemicals carefully.I would also like to thank my friends

and family, for supporting me morally. Last but not the least,

I would like to thank my institution for allowing me to do this

project and for providing me with all the necessary chemicals

that were required. It is all due to the support and concern

of the above people and institution that I could complete

my investigator project satisfactorily, without which things

would have never gone well.

ARPIT SHRINGI

CERTIFICATE

This is to certify that this project is submitted by ARPIT SHRINGI

student of class XII in the academic year 2012-13 of AADHARSHILA

ACADEMY and given satisfactory account of it.

Date :

Teacher Principal

(Signature) (Signature)

School Stamp

CONTENTS

S.No

.

Topic

1. INTRODUCTION

2. BENEFITS AND USES OF GUAVA

3. PROPERTIES / ACTIONS DOCUMENTED BY RESEARCH

4. FOOD VALUE PER 100 g OF EDIBLE PORTION

5. ACID BASE TITRATION

6. REDOX TITRATION

7. TO STUDY THE PRESENCE OF OXALATE ION IN GUAVA

FRUIT AT DIFFERENT STAGES OF RIPENING

8. BIBLIOGRAPHY

INTRODUCTION

Guava or psidum guajava is one of the various mystaceous

trees or shrubs of the genus psidum. When ripe, it has dark

or light green-colored peel which turns light yellow on

ripening, the pulp of the fruit is cream colored with many

seeds embedded in it.

Guava has the highest percentage of vitamin C among all

citrus fruit. It also contains oxalates, amount of which varies

during ripening of fruit. During the process of removal of two

equivalent hydrogen of vitamin C. (Ascorbic acid) molecules

take place. Dehydroascorbic acid is further oxidized to oxalic

acid in alkaline medium.

BENEFITS AND USES OF

GUAVA

1. Guavas are an excellent source of vitamin C and also contain ironcalcium, and phosphorus. The guava fruit contains the highest vitamin C content out of all the citrus fruits with as much as 180 mg per 100 g if fruit.

2. Older children and adults, a cup once or twice daily of a leaf decoction is the tropical herbal medicine standard.

3. A guava leaf decoction is taken to relieve colds and bronchitis.

4. The roots, bark, leaves and immature fruits, because of their astringency, are commonly employed to halt gastroenteritis, diarrhea, dysentery and vomiting in cholera patients.

5. It also has hypoglycemic and anti bacterial properties. The fruit, when eaten whole helps reduce both, high blood pressure and cholesterol levels.

6. Guava benefits in battling diabetes, combats cancer and protects prostate.

7. Guava can improve heart health by helping to control blood pressure and cholesterol.

8. Guava is highly effective in removing constipation.

PROPERTIES / ACTIONS

DOCUMENTED BY RESEARCH

Guava fruit acts as a : Amebicide, analgesic (pain

reliever), antibacterial, anticandidal, antidysenteric,

antifungal, antimalarial, antioxidant, antispasmodic,

antiulcerous, cardio depressant, cardiotonic (tones, balances,

strengthens the heart), central nervous system depressant,

cough suppressant, gastrototonic (tones, balances,

strengthens the gastric tract), hypotensive (lowers blood

pressure), sedative, vasoconstrictor).

Other Properties/Actions Documented by

Traditional Use

Guava fruit also has the following effects on human health :

Anti-anxiety, anticonvulsant, antiseptic, astringent, blood

cleanser, digestive stimulant, menstrual stimulant, neervine

(balances / calms nerves), vermifuge (expels worms).

Main Actions (in order) : Antidysenteric, antiseptic,

antibacterial, antispasmodic, cardiotonic (tones, balances,

strengthens the heart ).

Drug Interactions :

None reported, however excessive orchronic consumption of

guava may potentiate some heart medications.

Contraindications :

1. Guava has recently demonstrated cardiac depressant

activity and should be used with caution by those on

heart medications.

2. Guava fruit has shown to lower blood sugar levels and it

should be avoided by people with hypoglycemia.

FOOD VALUE PER 100 g OF

EDIBLE PORTION

ACID BASE TITRATION

When an acid base reaction is used, the process is called

acid-base titration. When a redox reaction is used, the

process is called a redox titration. Titration is also called

volumetric analysis, which is type of quantitative chemical

analysis.

Titration is a laboratory technique by which we can

determine the concentration of an unknown reagent using a

standard concentration of another reagent that chemically

reacts with the unknown. This standard solution is referred

to as the “titrant”. We have to have some way to determine

when the reaction is complete that we are using. This is

referred to as the “end point” or more technically the

equivalence point. At that point, the entire unknown has

been reacted with the standard titrant and some kind of

chemical indicator must let us know when that point has

been arrived at.

Generally, we know the Normality of the titrant since it is a

standard solution. We also pre-measure the volume of the

unknown. We then titrate with the standard from a burette

into the container with the measured unknown and the

chemical indicator until the indicator either turns color or a

precipitate indicates that the end point or the equivalence

point has been reached. Having the initial and final readings

of the titrant burette gives us the volume of the titrant used.

The only unknown in the above equation is the Normality of

the unknown.

Molarities of acidic and basic solutions are often used to

convert back and forth between moles of solutes and

volumes of their solutions, but how were the molarities of

these solutions determined? This section describes a

procedure called titration, which can be used to find the

molarity of a solution of an acid or a base.

In titration, one solution (solution #1) is added to another

solution ( solution # 2) until a chemical reaction between the

components in the solutions has run to completion. Solution

#1 is called the titrant, and we say that it is used to titrate

solution #2. The completion of reaction is usually shown by a

change of color caused by a substance called an indicator.

A solution of a substance that reacts with the solute in

solution #2 is added to a burette. (A burette is a laboratory

instrument used to add measured volumes of solutions to

other containers). This solution in the burette, which has a

known concentration, is the titrant. The burette is set up over

the Erlenmeyer flask so the titrant can be added in a

controlled manner to the solution to be titrated (figure 1) .

For example a 0.115 M NaOH solution might be added to a

burette, which is set up over the Erlenmeyer flask containing

the nitric acid solution.

REDOX TITRATION

Redox titration (also called oxidation reduction titration ) is a

type of titration based on a redox reaction between the

analyte and titrant.

It is a titration of a reducing agent by an oxidizing agent

between the analyte and titrant.

Redox reaction may involve the use of a redox indicator.

This experiment involves the use of potassium permanganate

which is the oxidizing agent as well as the indicator.

Permanganate ion is a powerful oxidizing agent, especially in

acidic solution, which can be used to analyze (by titration )

solutions containing many different species. In these titration

reactions, the intensely colored MnO-4 ion is reduced to form

the colorless Mn +2 ion.

An advantage of using the permanganate ion in the titration

of colorless unknown solutions is that it is “self indicating”. As

long as the reducing agent remains present in the sample,

the color of MnO-4 quickly disappears as it is reduced to

Mn+2. However, at the endpoint, all the reducing agent has

been used up so the next drop of MnO-4 solution is sufficient

to cause an easily detected color change, colorless (faint,

permanent peach / pink ). So we know that at the endpoint,

the oxidizing agent (MnO-4) and reducing agent (H2O2 or Fe +2)

have reacted in exactly in proportion to their stoichiometry in

the balanced redox equation. If we know how much of the

oxidizing agent we added, then we can figure out exactly how

much reducing agent was present in the unknown!

TO STUDY THE PRESENCE OF

OXALATE ION IN GUAVA FRUIT

AT DIFFERENT STAGES OF

RIPENING

REQUIREMENTS –

100ml measuring flask, pestle and mortar, beaker, titration

flask, funnel burette, weight box, filter paper, dilute H2SO4 N\

20 KMNo4, guava fruits at different stages of ripening.

THEORY -

Oxalate ions are extracted from fruit by boiling pulp with

dil.H2 SO4. Then oxalate ions are estimated volumetrically by

titrating the solution with standard KMnO4 solution.

PROCEDURE –

1. Weigh 50.0 gram of fresh guava and crush it to a fine

pulp using pestle –mortar.

2. Transfer the crushed pulp to a beaker and add about 5o

ml dilute H2 SO4 to it. Boil he contents for about 10

minutes.

3. Cool and filter the contents in a 100 ml measuring flask.

Make the volume up to 100ml by adding distilled water.

4. Take 20 ml of the solution from the measuring flask into

a. Titration flask and add 20 ml of dilute sulphuric acid

to it. Heat the mixture to about 60 0 C and titrate it

against N\20 KMnO4. Taken in a burette. The end point

is appearance of permanent light pink color.

5. Repeat the above experiment with 50.0 grams of 1, 2

and 3 days old guava fruit.

OBSERVATIONS :–

Weight of guava fruit taken each time = 50.0grams

Volume of guava extract taken in

each titration = 20.0 ml

Normality of KMnO4 solution = 1\20

OBSERVATION TABLE

Guava extract from Burette readings Concordant volume of N\20 KMnO4

solution used.

Initial Final

Fresh guava O ml 4.8ml 4.8ml

One day old guava O ml 4.1ml 4.1ml

Two days old guava O ml 3.6ml 3.6ml

Three day old guava O ml 3.0ml 3.0ml

The strength of guava fruit at different

stages of ripening -

Guava extract from Strength

Fresh 1.056 g/liters

One day old 0.902g /liters

Two days old 0.792g/liters

Three days old 0.66g/liters

RESULT:

It is concluded from above experiment that the

amount of oxalate ion in guava at different stages of

ripening decreases.

PRECAUTIONS:

1.) The apparatus must be clean.

2.) Handle acid with care.

3.) Balance should be accurate.

4.) Mix the content well.

5.) Take reading of lower meniscus.

BIBLIOGRAPHY

Chemistry Practical Manual

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