- Aligned with Big Idea 1 and Learning Objective 1.16
- Emphasizes Science Practices 1, 2, 3, 4, 5, 6, and 7
Determine the concentration of food dyes in powdered drink mixes using Beer-Lambert’s law. Teach this laboratory experience using either the guided activity or inquiry activity. In the guided activity, students prepare solutions of known concentration for each of 2 food dyes, measure each solution’s absorbance, and graph a calibration curve for each food dye. Students then use their data and curve to determine the concentration of food dye in unknown solutions containing a single food dye.
The inquiry activity allows students to design a procedure to determine the concentration of each food dye in its unknown solution. Students must choose the concentrations of the standard solutions that will allow them to interpolate the concentration of food dye in the drink mix and prepare the solutions. It also provides opportunity for students to present their experiment’s design and results, reinforcing the practice of communicating findings. Detailed preparation and procedure notes guide you through leading a successful inquiry exercise, including a suggested rubric for assessing student performance.
Both activities include Big Idea assessment questions that follow the AP® Chemistry Exam free-response question format. In the Big Idea assessment, students are given absorbance data for a complex ion, asked to identify the wavelength of maximum absorbance, plot provided data to generate a calibration curve, and determine the concentration of the complex ion.
This kit provides the following AP® Chemistry experiences: design a procedure to collect data; analyze data; perform error analysis; plot calibration curves, and interpolate data from the curves. Because the experiment uses food dyes rather than thiocyanate salts, it is safer and generates no hazardous waste. Materials are sufficient for 30 students working in teams of 3. Digital teacher’s manual, included FREE with kit purchase or sold separately, is a 12-month eBook license to the Spectrophotometric Analysis of Food Dyes teacher’s manual. You can also access the digital student guide for this kit for free at
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