March 1 - March 4, 2010
Report Sheets for Experiment 16-077 and 17-044 are due this week.
The data from all the Chemistry 102 sections will be posted on blackboard by the end of this week. There is no lab next week but the report for Experiment 18-201 is due to Dr. Chanatry (Wynn B37) by 9:00 am on Friday, March 11, 2010 (before you leave for spring break). Lab resumes on Monday March 22nd.
EXPERIMENT 18-201: Determination of Vitamin C Content of Citrus Fruit Juice.
The purpose of this laboratory experiment is to determine the amount of vitamin C in various citrus fruit. This experiment presents a challenge for the adventurous among you (actually for all of you). You will use chemistry and techniques that you are familiar with to meet this challenge. The ultimate goal of this experiment is to decide the best citrus fruit to pack to prevent an outbreak of scurvy for a 20-person crew embarking on a 50 day voyage at sea. You can think of this as your very own “Survivor” challenge, or perhaps the “Oregon Trail” game at sea. Your mission is to use your expertise in the laboratory to collect and analyze the relevant data in order to prevent an outbreak of scurvy on your journey.
Experimental.
The method used to analyze for ascorbic acid (vitamin C) involves chemistry we have seen before. We are going to use an oxidation-reduction reaction and a technique that you are familar with – titration. Vitamin C is easily oxidized so we can use this chemical reactivity to detect vitamin C in solution.
In the first part of the experiment, a sample of ascorbic acid is oxidized by iodine. The ascorbic acid will be titrated with potassium iodate, KIO3. Using the titration volume of KIO3 needed to reach the endpoint, you can determine the mass of ascorbic acid per volume of KIO3. This conversion factor will allow you to determine the vitamin C present in a sample of citrus fruit juice.
In the second part of the experiment you are going to test various citrus fruits and determine the vitamin C content of each fruit. You will be working in groups of two or three and each lab section will be responsible for testing one citrus fruit. The data from all chemistry 102 lab sections will be compiled and posted on blackboard. Using this data, we challenge you to decide the optimal cargo of fruit that must be packed to prevent scurvy during your voyage.
Chemistry 102 Laboratory Home Page
Last Updated: