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The objective of this experiment is to determine the vitamin C content of a lemon.

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Introduction

Aim: The objective of this experiment is to determine the vitamin C content of a lemon. Apparatus: Lemon juice, vitamin C solution (fresh, 0.1%), 2 test tubes, test tube rack, pipette to measure 2.00 cm3 volume, DCPIP (dichlorophenolindophenol, 0.1% aqueous solution). Procedure: The lemon juice and vitamin C solution were provided by the teacher. The vitamin C solution was made up to contain 0.001 g vitamin C in 1.0 cm3 water. (i) Using a pipette, place exactly 2.00cm3 of DCPIP solution into a test tube. (ii) Using a different graduated pipette, add the vitamin C solution, drop by drop, to the DCPIP solution in the test tube. ...read more.

Middle

(vi) The next step is to find the volume of lemon juice which contains the equivalent mass of vitamin C. To find this, repeat steps (i)-(iii) using lemon juice (add the lemon juice drop by drop to 2cm3 of DCPIP solution in a test tube until it becomes decolorized. Record the exact volume of lemon juice added). (vii) Repeat Step (vi). Average the two results. This is the volume of lemon juice which contains the mass of vitamin C calculated in Step (v). (viii) Work out the mass of vitamin C in 1.00 cm3 of lemon juice. Data Collection: Vitamin C needed to decolorize 2.00cm3 of DCPIP Trial 1 Trial 2 Average 1.12 mL 1.12 mL 1.12 mL Lemon Juice needed to decolorize 2.00cm3 ...read more.

Conclusion

1.12 mg * 120 mL / 1.41 mL = 95.3 mg vitamin C / lemon Conclusion: The major source of error in this investigation is that we did not take an exact measurement of the volume of the lemon, but rather approximated the volume to 120 mL. This leads to an inaccurate result. Experimentally we found that a lemon contains about 95 mg of vitamin C. The recommended daily intake is 60 mg but researchers are thinking of increasing the value to 100-200 mg. The reason for this is that ascorbic acid is found to be an antioxidant (abundant in fruits and vegetables), that is, it protects the cardiovascular system and prevents scurvy as well as the oxidation of cholesterol, which in turn decreases the possibility of heart attacks and strokes. ...read more.

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