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Experimental Design for Orange Juice, Vitamin C

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What Type of Orange Juice has the Most Vitamin C?

Introduction

Question: What type of orange juice has the most vitamin c?

Hypothesis: Freshly squeezed orange juice will have the most vitamin C compared to the other types of orange juice and drinks, because the fruit is picked fresh, and it is not stored, preserved or exposed to oxygen.

Materials i. Vitamin C Indicator Solution a) One tablespoon of cornstarch b) Water c) 250 milliliters of boiling water ii. Two percent iodine solution iii. Medicine dropper. iv. (6) Disposable pipettes. v. (1) Stirring rod. vi. Cheesecloth vii. Distilled water viii. Masking tape ix. Permanent marker x. Small funnel xi. …show more content…

p. Add 10 drops of starch indicator solution. q. Set up the 50 mL buret on the the ringstand. r. Fill the buret nearly full with your iodine titration solution. s. Write down the initial volume of the iodine titration solution in the buret. t. Place the Ehrlenmeyer flask (containing the vitamin C and starch solutions) under the buret. u. Carefully release the spring clamp of the buret to add iodine solution drop by drop. v. Swirl the flask to mix in the iodine solution after each addition. w. The titration is complete when the iodine creates a distinct color change in the juice/starch solution. This color change will be harder to see than with the vitamin C solution, since the juice starts out orange. The color will change from orange to grayish brown when the endpoint is reached. If you continue to add iodine, the color will darken further. You want to note the volume of iodine added when the color first changes. x. Record the final volume of the iodine solution in the buret. y. The difference between the initial volume and the final volume is the amount of iodine titration solution needed to oxidize the vitamin C. z. Repeat this step three times. You should get results that agree within about 0.1 mL. viii. For each juice (fresh, premium, or from-concentrate), calculate the average amount of iodine needed to titrate a 20 mL

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