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Laboratory Class Objectives You should perform the following titrations in pairs. To successfully complete this experiment you should read and follow the following general procedures: Using a volumetric flask Using a volumetric pipette Using a burette Your first objective for this class is to perform a redox titration on vitamin C tablets (Berocca) as described below in Part 1. From your assay data you must determine the amount of vitamin C in the tablet you used (stated content is 500 mg per tablet). Your second objective is to carry out a redox titration on packaged orange juice as detailed on Part 2. As for the previous assay, you must determine the amount of vitamin C in this juice (for stated content, check the nutrition information on the label). * Chemicals needed 0.005 mol L + Iodine solution . . Equipment needed Burette and stand 100 mL beaker 100 mL volumetric flask 250 mL conical flasks • 5 and 20 mL volumetric pipettes 10, 25 and 50 mL measuring cylinders Stirring rod Spatula/spoon Starch powder Vitamin C tablets (Berocca) Commercial orange juice .
- Part 2 - Titrimetric Analysis of Vitamin C in Fruit Juice 1. Use a volumetric pipette to transfer 20.00 mL of the packaged orange juice into a clean or pre-rinsed 250 mL conical flask. 2- Add 45 mL deionised water to bring the total volume of the flask to 50 mL. 3- Add 1 teaspoon of solid starch powder indicator to the diluted solution and swirl well to mix. 4- Titrate the sample with the provided standardised iodine solution (0.005 mol L-iodine). The endpoint of the titration is identified as the first permanent trace of a dark blue black colour due to the starch-iodine complex. 5. If possible, repeat the titrations with further aliquots of sample solutions until you obtain concordant results (titres agreeing within 0.1 mL). 6- Record all data collected in the table below. 7- Calculate an average value for the titre values that you have chosen. Justify any exclusions you have made. Initial burette reading Final burette reading Iodine volume consumed Sample 1 Sample 2 Sample 3 Sample 4 Average 8- Calculate the amount of vitamin C in the original packaged orange juice in mg. Take into account any dilutions you may have needed to make.