(Solved): find the purpose and hypothesis Analysis of Vitamin C Purpose Hypothesis Facts to Know Vitamins are ...

Analysis of Vitamin C Purpose Hypothesis Facts to Know Vitamins are complex organic molecules required in small amounts by the body at regular intervals in order to maintain health and well-being. Generally, the daily requirements of the various vitamins are very small quantities, but whenever these small quantities are not available, the body cannot function properly. For example, if a person's diet does not include a sufficient amount of vitamin \( \mathrm{C} \) (the Food and Drug Administration recommends around 50 milligrams per day) a disease called scurvy results. In this experiment you will learn to analyze a sample of material for vitamin \( C \) content using a technique called titration. The analysis makes use of the reactivity of vitamin C. Both iodide (V) ions and iodate \( \left(\mathrm{IO}_{3}^{-}\right) \)ions are added to a solution containing the vitamin \( \mathrm{C} \) along with some starch. First, the iodide and iodate ions react with each other to form elemental iodine \( \left(b_{2}\right) \). The vitamin \( C \) then reacts with the \( I_{2} \), consuming the vitamin \( C \) in the process. When all of the vitamin C has reacted, the next tiny amount of iodine formed reacts with the added starch to produce a deep blue color. The appearance of this blue color signals that all of the vitamin C has reacted and that the titration is finished. This is called the endpoint of the titration. PART I - Analysis of Commercial Vitamin C Tablets: 1. Clean, rinse and fill a buret with \( 0.050 \mathrm{M} \mathrm{KIO}_{3} \) (ie, potassium iodate) solution. 2. Crush one vitamin C tablet in a mortar and pestle. Dissolve this in about \( 150 \mathrm{~mL} \) of distilled water using a \( 250-\mathrm{mL} \) conical flask. Note that some insoluble material (that is not vitamin C) remains from the tablet. 3. To the flask containing the dissolved vitamin C add \( 5.0 \mathrm{~mL} \) of \( 1.0 \mathrm{M} \mathrm{HCl} \) (this speeds up the reaction between the \( \mathrm{I} \) and the \( \left.10_{3}^{-}\right), 10.0 \mathrm{~mL} \) of \( 0.60 \mathrm{M} \mathrm{KI} \) solution, and 10 drops off freshly prepared starch indicator solution. Place on a heater/stirrer and use a Teflon stir bar to mix solution during titration, but do not heat the solution. 4. Return to the buret with \( \mathrm{KIO}_{3} \) solution and take an initial buret reading to one decimal place ie, the tenths place; this is your \( 1^{\text {st }} \) data point to record (1). Open the buret valve and slowly (ie, dropwise fashion) add \( \mathrm{KIO}_{3} \) solution from the buret to the vitamin \( \mathrm{C} \) solution. Add until the mixture in the flask turns a permanent bluish-purple color. 5. Record the final buret reading (2). Subtract the initial buret reading ftom the final buret reading to detemine the volume of the \( \mathrm{KIO}_{3} \) solution required for the titration (3). 6. Repeat steps 2 through 5 with a second vitamin C tablet (4), (5), (6). PART II-Analysis of Tang: 1. Weigh out 12-15 \( \mathrm{g} \) of Tang and record the weight (7). Place in a flask. 2. Add about \( 150 \mathrm{~mL} \) of distilled water, \( 5 \mathrm{~mL} \) of \( 1.0 \mathrm{M} \mathrm{HCl}, 10 \mathrm{~mL} \) of KI solution, and 8 drops of starch indicator solution. 3. Titrate carefully as before ( 8 ), (9), (10), Remember, the color of the solution will be a: composite of the Tang color and the color of the indicator. The endpoint will be indicated by a color change, but not necessarily to blue-black. The endpoint may be indicated by a brown or green color.