Experiment: Determination of Vitamin C Content in Fruit Juice
Purpose:
* To quantify the amount of Vitamin C (ascorbic acid) in a sample of fruit juice using an iodine titration.
Materials:
Fruit juice sample Standard solution of Vitamin C
Starch solution Iodine solution
Burette Erlenmeyer flask
Graduated cylinder Pipette
Procedure:
1. Prepare the Vitamin C standard solution: Dissolve a known weight of Vitamin C in water to make a solution of known concentration.
2. Pipette a known volume of fruit juice into an Erlenmeyer flask: Typically, 10-25 mL is used.
3. Add starch solution to the fruit juice: This will serve as an indicator for the titration.
4. Fill a burette with iodine solution: Record the initial volume.
5. Titrate the fruit juice with the iodine solution: Add the iodine solution dropwise while swirling the flask until a faint blue-black color persists for at least 30 seconds.
6. Record the final volume of iodine solution: This will give the volume of iodine required to react with the Vitamin C in the fruit juice.
7. Calculate the concentration of Vitamin C in the fruit juice: Use the stoichiometry of the reaction between Vitamin C and iodine to determine the concentration of Vitamin C in the juice.
Key Procedures:
Maintaining the temperature of the solutions Using accurate glassware for precise measurements
Observing the endpoint of the titration carefully Repeating the titration multiple times to ensure accuracy
Significance:
Vitamin C is a water-soluble vitamin essential for various bodily functions. Determining its content in food samples allows for quality control and nutritional assessment.
* The redox reaction used in this experiment demonstrates the analytical techniques employed in analytical chemistry to quantify substances in different samples.