oxalate ions in guava.doc
- 1. Chemistry Project Report On “Study the presence of oxalate ions in guava fruit at different stages of ripening” Session: 2015-16 Under Supervision of Submitted by Ms. Poonam Chauhan Rajiv Verma Lecturer in Chemistry Roll No…………… Class XII (Medical)
- 2. MAHARANA PRATAP PUBLIC SCHOOL, KURUKSHETRA
- 3. CERTIFICATE This is to certify that the project titled “Study the presence of oxalate ions in guava fruit at different stages of ripening”, has been undertaken by Rajiv Verma, Roll No. a student of XII (Medical). This project has been carried out as a part of Chemistry projects as prescribed by the Central Board of Secondary Education. This work is done by candidate’s own efforts. Ms. Poonam Chauhan Lect. in Chemistry
- 4. ACKNOWLEDGE MENT I express my deep sense of gratitude to Ms. Poonam Chauhan, Lecturer of Chemistry, Maharana Pratap Public School, Kurukshetra for her inspiration, valuable guidance and constant encouragement in the completion of this project. Without her it would have been an impossible task for me. I have put my sincere effort to make this project interesting. I have fully consulted all the available books on this subject and I am thankful to esteemed authors Rajiv Verma Class 10+2 Medical Roll No.
- 5. Introduction Guava is mainly a winter fruit. It has many medicinal properties and cultivated in almost all parts of India. Approximate composition of this fruit is Constituent % Amount Water 76.10 Proteins 1.50 Fats 0.20 Calcium 0.01 Phosphorus 0.04 Vitamin 0.30 Organic matter 14.50 Guava fruit contains maximum amount of Vitamin C after ‘Amla’. But amount of Vitamin C decreases with the ripening of the fruits. Probably vitamin C gets converted to oxalate with ripening of the fruit. Thus, amount of oxalate in the fruit may be a reflection on the amount of vitamin C in it and its detennination, therefore, makes an important study.
- 6. Objective:- Determination of the oxalate ions in guava fruit at different stages of its ripening. Theory:- Oxalate content of the fruit is made to go into solution by boiling its pulp with distilled water and its amount in the solution is determined by redox titration using potassium permanganate solution. Apparatus: Pestle and mortar, beakers, 20ml measuring flask, funnel, burette, pipette, conical flask, wire gauze. iron stand, tripod stand and knife.
- 7. Chemicals. 0.05N KMnO4 solution, dil. H2 SO4 distilled water fully riped, semi-riped and raw guava. Procedure. (i) Take one fully riped guava and peel off its skin. Weigh 25g of this. (ii) Make very small pieces of this with the help of a knife and crush these in clean pestle and mortar. (iii) Transfer the pulp so obtained into a 250 mL beaker. Wash the pestle and mortar well with about 100 mL of distilled water and transfer the washings also into the beaker. (iv) Boil the contents of the beaker for about 10 minutes. Cool and filter through a funnel. Collect the filtrate in a 250 mL, measuring flask. Make the volume upto the mark i.e. 250 mL by adding distilled water. Label the flask as riped guava solution.
- 8. (v) Similarly, prepare 250 mL solution of 25g semi-riped and raw guava. (vi) Now, pipette out 25 mL of solution from one of the flask into a conical flask. Add 20 mL of dilute sulphuric acid to it. Warm the flask to about 60°C and titrate it with 0.05 N KMnO4 solution until colour of the solution just changes to permanent pink. Repeat the experiment with same solution till three concurrent readings are obtained. (vii) Similarly, find out the amount of 0.05 N potassium permanganate solution required for titration in the other two guava solutions. (viii) Compare the three titre values i.e. volume of KMnO4 consumed for 25 mL of the three guava solutions. The guava solution which consumes maximum volume of the permanganite solution contains maximum oxalate ions.
- 9. Precautions:- (i) Do not mix the three fruits or their solutions. (ii) Boil the crushed fruit with equal amount of water and for the same length of time in all the three cases. (iii) Wash the pestle and mortar well before using for the other. (iv) Weighing should be done accurately.
- 10. Observations: Normality of the KMnO4 solution 0.05N End point Colourless to pink Volume of the guava solution taken each time for titration 25 rnL Guava solution Burette readings Volume of the KMnO4 used in mL Concurrent reading in mL Initial Final Riped Guava …………. …………. ……………….. x1 Semi-riped Guava …………. …………. ……………….. X2 Raw Guava …………. …………. ……………….. X3 (The sample having the highest titre value has the maximum amount of oxalate) Conclusion:- The amount of oxalate ions…………… with the ripening of