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
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
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
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.
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.
Guava fruit acts as a : Amebicide, analgesic (pain reliever),
antibacterial,
antifungal,
antimalarial,
anticandidal,
antidysenteric,
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.
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 (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 -4
reactions, the intensely colored MnO 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, -4
the color of MnO
quickly disappears as it is reduced to
+2
Mn . However, at the endpoint, all the reducing agent has -4
been used up so the next drop of MnO solution is sufficient to cause an easily detected color change, colorless (faint, permanent peach / pink ). So we know that at the endpoint, -4
+2
the oxidizing agent (MnO ) and reducing agent (H 2O2 or Fe ) 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!
REQUIREMENTS – 100ml measuring flask, pestle and mortar, beaker, titration flask, funnel burette, weight box, filter paper, dilute H 2SO4 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 KMnO 4 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.
Chemistry Practical Manual
www.scribd.com
www.google.com
