Objective:
- To determine whether the concentration of Vitamin C in a fruit juice changes upon heating at a constant temperature for different periods of time.
- To investigate how the trend goes (whether the concentration of Vitamin C increases or decreases) if the amount of Vitamin C does change.
Theory:
- Hypothesis: The concentration of Vitamin C in the fruit juice changes and decreases upon heatingat a constant temperature for increasing periods of time.
- Method to test hypothesis: The hypothesis can be tested by first determining the amount of ascorbic acid needed to decolourize 3mL of DCPIP solution, and calculating the concentration of Vitamin C in the ascorbic acid. Next, determine the amount of fruit juice needed to decolourize 3mL of DCPIP solution, and calculating the concentration of Vitamin C in the fruit juice initially. Then, heat a few test tubes of fruit juice in a boiling water bath for different periods of time- 3min, 7min, 11min, and 15 min. The test tubes should hold amounts of fruit juice that are more than the amount of fruit juice needed to decolourize 3mL of DCPIP initially. Take out the test tubes at the designated times and calculate their concentrations. Finally, the concentrations can be compared and the trend can be shown.
- Assumptions: Heating the test tubes for different periods of time provide environments where different amounts of heat are exerted onto the orange juice and the concentration of Vitamin C may be affected. It is suggested that the test tubes should hold amounts of fruit juice that are more than the amount of fruit juice needed to decolourize 3mL of DCPIP initially, as this allows investigation for whether more or less juice is needed, thus whether the concentration is decreased or