Hello,

I need help with this lab. Specifically with questions #4,#5,#7 in the post lab questions. I'm not sure how to calculate the answer. Thank you.

Vitamin C in Fruit Juices and Capsules Goals: fter completing this lab activity, you should be able to: - Perform a titration to determine the concentration of vitamin C in solution. - Calculate the amount of vitamin C in a known quantity of solution. - Compare the amount of vitamin C in your sample to dietary standards. Materials and Equipment: Spot plates; Beral pipets, thin-stem (short); pieces of white paper. Ascorbic acid standard solutions: (1.00mg/mL and 10.00mg/mL); samples of orange juice, apple juice, white grape juice; standard starch solution; standard iodine solution. Introduction: Ascorbic acid is commonly known as vitamin C. This water soluble compound is found in many fruits and vegetables. In the human body, vitamin C is known as an essential vitamin, which means that it must be consumed through the food, drinks or supplements that we ingest. We cannot synthesize it in our own bodies. It is also water soluble, which means the body has a limited ability to store vitamin C. The primary function of vitamin C is maintaining collagen, which is a protein necessary for the formation of connective tissues in our ligaments and bones. Deficiency of vitamin D can lead to serious conditions, such as scurvy. In this lab activity, we will use a standard solution of ascorbic acid which has been prepared by the stock room. The titration, which a comparison of the behavior of two solutions of possibly different concentration, is the method by which a concentration of an unknown may be determined. Using the equation: (THE STANDARD ASCORBIC ACID SOLUTION = 1.00 MG ASCORBIC ACID / ML OF SOLUTION.) An Example: Suppose the average number iodine drops to titrate the standard solution is 40 drops. Using the same iodine solution, if the average number iodine drops to titrate the fruit juice is 20 drops, the relationship would be as follows: 1.00mg/mL ascorbic acid 40 drops iodine =xmg/mL ascorbic acid in juice 20 drops iodine Solving for x gives the fruit juice a concentration of 0.5mg/mL. To calculate the quantity of ascorbic acid in one serving of the juice requires some simple conversions. Note: There are 8.0oz in one serving and there are 30.mL in 1.0 ounce. Procedure for Fruit Juices: Safety and chemical hazards: Iodine solution-irritates eyes and is somewhat corrosive to skin. It will stain your clothing and paper. Wear chemical splash goggles and chemical-resistant gloves. Waste disposal: Place your titrated solutions into the halogenated waste container in the fume hood. The asiest way to do this is to rinse the contents of your spot plate into a beaker with a small amount of water. Page 2 of 5 6. Dobtain approximately 1mL of the standard ascorbic acid solution in a clean test tube. The concentration should be noted on the stock room label as 1.00mg ascorbic acid / mL of solution. To titrate the ascorbic acid solution: place ten drops of the solution into a well of the reaction plate (spot plate). Add five drops of starch solution to the same well. Now titrate with the iodine solution a drop at a time. Record the number of drops of iodine solution required to make the mixed solution turn blue-grey. Repeat the titration five more times and calculate the average number of drops required to titrate the ascorbic acid standard. Record this information on your report sheet. Wash your pipet before testing a new solution. 2. To titrate the apple juice: place ten drops apple juice into a well of the reaction plate (spot plate). Add five drops of starch solution to the same well. Now titrate with the iodine solution a drop at a time. Record the number of drops of iodine solution required to make the mixed solution turn blue-grey. Repeat the titration five more times and calculate the average number of drops required to titrate the apple juice. Record this information on your report sheet. Wash your pipet before testing a new juice. 3. Repeat the titration with each of the other juices, recording the results of the six titrations for each juice and calculating the average number of drops required to titrate each juice. Record the data and calculations on you report sheet. 4. Calculating the Results of the Titrations Using the equation: Standard concentration average drops iodine = Juice concentration average drops iodine, (The standard ascorbic acid solution =1.00mg ascorbic acid /mL of solution) 5. Analysis: Compare the data for the juices that you obtained with the minimum daily requirements provided by your instructor. rocedures for Vitamin C Capsules: 1. You will titrate a more concentrated solution for the Vitamin C capsules section of this lab. Obtain approximately 1mL of the standard ascorbic acid solution in a clean test tube. The concentration should be noted on the stock room label as 10mg ascorbic acid / mL of solution. To titrate the ascorbic acid solution: place 10 drops of the solution into a well of the reaction plate (spot plate). Add five drops of starch solution to the same well. Now titrate with the iodine solution a drop at a time. Record the number of drops of iodine solution required to make the mixed solution turn blue-grey. Repeat the titration five more times using clean wells, and calculate the average number of drops required to titrate the ascorbic acid standard. Record this information on your report sheet. Wash your pipet before testing a new solution. 2. To titrate the vitamin C capsule solution. Open a vitamin C capsule and dissolve the powder in enough distilled water to form 100mL of vitamin C solution. If the capsule used is a 500mg capsule, the 250mg concentration of the vitamin C solution should be 500mg/100mL Page 3 of 5 Titrate the vitamin C solution from the capsule the same way as in step 1. Place 10 drops of your vitamin C capsule solution into a well of the reaction plate (spot plate). Add five drops of starch solution to the same well. Now titrate with the iodine solution a drop at a time. Record the number of drops of iodine solution required to make the mixed solution turn blue-grey. Repeat the titration five more times and calculate the average number of drops required to titrate the vitamin C capsule solution. Record this information on your report sheet. Wash your pipet before testing a new solution. 3. Calculating the Results of the Titrations Using the equation: Standard concentration x average drops iodine = Juice concentration x average drops iodine (The standard ascorbic acid solution =10.00mg ascorbic acid /mL of solution) Data for Fruit Juices: Enter drops of iodine solution used for each trial Show your calculations for the concentrations of juices per ml, and per 6 oz serving and compare to the stated value on the package/label. Apple: 111.00mg/mL=5Cmg/mL Pineapple :111.00mglm=8xcmg/mL ecord the number of drops of iodine solution used for each trial Post-lab Questions: 1. Compare your result for the amount of vitamin C per 6 oz serving to the manufacturer's label. Is it the same or different? The mg of vitamin C per serving in our results was different from the manufacturer's label. 2. If it is different, why do you think that is the case? I think they are different the manufacturer might have had more trials or more accurate ways to test for the amount of vitamin C in their product. 3. What is the concentration (mg/mL ) of ascorbic acid in standard solution? (Get value from the bottle) The concentration (mg/mL) of the absorbic acid in standard solution is 10mg/ml. 4. Show your calculation for the concentration (mg/mL) of ascorbic acid in the initial vitamin C capsule solution that you prepared? 1610.0mg/mL=24xmg/mL1616x=16240=15mg/mL 5. Show your calculation for the average experimental concentration (mg/mL) of ascorbic acid in vitamin C capsule? 6. What is the stated number of milligrams in vitamin C capsule? 250mg. 7. What is the percentage difference between experimental and theoretical values. 8. What are some of the conditions that could result from a deficiency of ascorbic acid (vitamin C)