Description
Determine the concentration of ascorbic acid in a commercial fruit juice by redox titration.
Teach this laboratory experience using either the guided activity or inquiry activity. In the guided activity, students titrate solutions of known ascorbic acid concentration to create a standard curve then titrate a sample of fruit juice and determine the concentration of ascorbic acid from the curve. In the inquiry activity, students design an experiment to determine the concentration of ascorbic acid in a sample they choose.
The inquiry activity provides an opportunity for students to present their experiment’s design and results, reinforcing the practice of communicating findings. Detailed preparation and procedure notes guide you, the teacher, through leading a successful inquiry exercise, including a suggested rubric for assessing student performance.
Both activities include assessment questions that follow the format of the AP® Chemistry exam free-response questions. In the assessment, students write and balance half-reactions and net ionic equations for 2 different redox titrations and use the data provided to calculate the concentration of analyte in each experiment. These exercises give students practice working with multiple redox titration experiments as well as balancing complex redox chemical equations.