CHEM 181 Chapter : woc 4- vitamins a to k.docx

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CHEM 181 Full Course Notes

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Vitamins pages 129 to 132- vitamins a to k. Vitamins are substances that must be included in the diet in order to maintain health and prevent certain deficiency diseases: deficiency diseases include scurvy (thousands of sailors perished from this disease). First treated by boiling leaves of a tree and drinking the tea (treatment by the stadacona people). In the 17th century, some ships of the. East india company carried supplies of lemon juice to ward off the disease. Scottish physician james lind had heard accounts of treating scurvy with various foods or beverages and decided to get to the bottom of it. On a ship, he selected 6 pairs of men. To each pair he gave one of the following daily doses: cider; dilute sulfuric acid; vinegar; sea water; a mash of garlic, mustard seed and radish root; or two oranges and a lemon.

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Show transcribed image text 47 EXPERIMENT 47 Report Sheet 1. The kind of fruit drink appl Jwic 2. Molarity of iodine solution ad 3. Titration results Sample 1 (100 mL) Sample 2 (20.0 mL) Sample 3 (30.0 mL) a. Initial buret reading b. Final buret reading c. Total volume of iodine ,',ã¼, mL u. 2 mL 2.5 mL 4.amL 10.5 mL 10.5 mL 20.5 mL solution used: (b)-(a) 4. The weight of vitamin C in the fruit drink sample: [(3c) x 1.76 mg/mL] 5. Concentration of vitamin C in the fruit drink (mg/100 mL): [(4)/volume of drink] x 100 O,20,30 5S 6. Average concentration of vitamin Cin the fruit drink 52 mg/100 mL
Post-Lab Questions 1. Use the average concentration of vitamin C from your data, and calculate the volume that would satisfy your minimum daily requirement of vitamin C. Show your work 2. Vitamin C is ascorbie acid. If you examine the structure of ascorbic acid given in the Background t. In the structure shown, the ascorbic acid is section (equation 2), there is no -COOH grou - as a lactone or cyclic ester. Write the equation for the hydrolysis (cleavage by addition of water) of E ste the lactone to the carboxylic acid. 3. Write the net ionic equation for the conversion of iodine, la, to iodide, I. What kind of reaction is this? 4. Refer to the Background section and examine the chemical reaction for the oxidation of ascorbic acid (equation 2) a. What happened to the hydrogen atoms that were present in the ascorbic acid? b. Acid was added in the titration, but it is not present in equation (2) in a stoichiometric amount. So, what is the purpose of the acid? 5. The iodine for this experiment is in the form of 15, and not 12 (see equation (1), Background section]. Why is this form of iodine used? 577
ts for General Organic and Blochemistry Bettelheim/Landesberg Vitamin C is oxidized by 12 (as 15) according to the following chemical reaction: HO-CH- CH2OH HO-CH-CH,OH O. . o 2HI Ð½ Ð¾Ð½ Ð¾Ð½ Oxidized product (MW 174) (MW 254) Vitamin C (MW 176) As vitamin C is oxidized by iodine, I2 becomes reduced to I. When the end point is reached (no vitamin C is left), the excess of 12 will react with a starch indicator to form a starch-iodine complex, which is blackish-blue in color. I2 +starch iodine-starch complex (blackish-blue) It is worthwhile to know that although vitamin C is very stable when dry, it is readily oxidized by air (oxygen) when in solution; therefore, a solution of vitamin C should not be exposed to air for long periods. The amount of vitamin C can be calculated by using the following conversion factor 41 mL of 12 (0.01 M) = 1.76 mg vitamin C OBJECTIVE To determine the amount of vitamin C that is present in certain commercial food products by the titration method. Pro to this laboratory, there are techniques that you should revieo. You uoll find the relevant techmiques in the following experiments: (a) Use of the Spectroline pipet filler is in Experiment 2; (b) buret use and titration techniques are im Experiment 19.
terps Tile logical antioxidant (reducing agent). It helps to keep the iron in the yme, prolyl hydroxylase, in the reduced form and, thereby, it helps to to prevent scurvy is ascorbic acid. It is a powerful Acave ingredient in fruits and intain th thesis of normal ions and broken blood vessels. e enzyme activity. Prolyl hydroxylase is essential for the collagen. In scurvy, the abnormal collagen causes skin Vitamin C cannot be synthesized tained from the diet ( in the human body and must be e.g., citrus fruits, broccoli, turnip greens, sweet ppers, tomatoes) or by taking synthetic vitamin C (e.g, vitamin C blets, "high-C" drinks, and other vitamin C-fortified commercial foods). he minimum recommended adult daily requirement of vitamin C to y is 60 mg. Some people, among them the late Linus Pauling, wice Nobel Laureate, suggested that very large daily doses (250-10,000 ng) of vitamin C could help prevent the common cold, or at least lessen he symptoms for many individuals. No reliable medical data support this At present, the human quantitative requirement for vitamin C is still revent scurv claim. In this experiment, the amount of vitamin C is determined quantita- tively by titrating the test solution with a water-soluble form of iodine, I5: controversial and requires further research. [I: 1:1: -(triioode ion) (1) :11:+:1:-- Expanded octets 569

4. what are the products formed by digestion of the followingnutrients?

a. carbohydrates

b.fats

c. proteins

8. give definitions for the following words and terms as appliedto fats and fatty acids

a. saturated

b. monounsaturated

c. polyunsaturated

d. partially hydrogenated

12, what are the major cateogries of information required on anutrition facts label?

16. overdoses of which of the following vitamins shoulddefinitely be avoided? Why?

a. riboflavin

b. vitamin c

c. vitamin a

d. vitamin b

e. vitamin d

18. what is the gras list?

24, lactose is sometimes refeered to as milk sugar because it isthe principal carbohydrate in milk. the lactose structure follows.is this a monosacharide, disaccharide, orpolysaccharide?explain

28. folic acid is found in citrus fruits and leafy greenvegetables. the fda is now requiring that folic acid be added tocereals, breads, and pastas. The american journal of public healthysays that such grain fortification would prevent 300 to 700 birthdefects per year. at the level recommended for addition,approximately 3.25 million adults over 50 would recieve too muchfolic acid. what question would you want to answer before you wouldsupport such a nationwide program?

30. should the government embark on a national program to addmore calcium to our diets to reduce our chances of calciumdeficiency and osteoporosis? giv eone reason for such a program andone against.

34. what foods have you eaten during the past week that did notcontain any food additive?

2. give definitions of the following terms

a. over-the-counter drug

b. prescription drug

c. generic name for a drug

d. trade name for a drug

4. what are antibotics?

10. for what disease or condition is each of the followingclasses of drugs used?

a. analgesics

b. antipyretics

c. antibiotics

d. antihistamines

16. describe the following and give an example of each

a. schedule 1 drugs

b. schedule 2 drugs

20. name a drugh that might be used to treat angina

28. what are the applications for the following drugs?

a. tylenol

b. ibuprofen

30. how are cocaine and crack related?

38. describe the normal steps in the action of aneurotransmitter at a nerve synapse

42. the fda requires extensive testing of a prospective drug.the process can take almost 12 years. other countries have muchshorter approval processes. imagine that you have a close relativewho is suffering from a serious illness and an effective drug isavailable only outside the united states. what are the possiblecourse of action? what would you do?

CHEM 181 Chapter : woc 4- vitamins a to k.docx

CHEM 181 Full Course Notes

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