This lab experiment is designed to introduce the electromagnetic spectrum to non-science majors in a food chemistry course by using everyday food (i.e. Kool-Aid packets). Students will use a spectrophotometer to correlate wavelength to color, as well as determine the mass percent of certain colored dyes in a Kool-Aid sample. Paper chromatography is also introduced to determine the number of dyes in a Kool-Aid sample. This lab is adapted from Sigmann, S; Wheeler, D. J. Chem. Ed., 2004, 81, p. 1475.
After completing this experiment, the student will be able to:
- Correlate color to wavelength of light
- Analyze Kool-Aid packets to find the number of dyes present by paper chromatography
- Generate a Beer's law calibration curve
- Calculate the percent mass of dye in Kool-aid
- White Chalk
- Strawberry, Ice Blue Raspberry, Grape, Cherry Kool-Aid packets
- Coffee Filters
- Drinking water
- Red Dye #40
- Blue Dye #1
- Gallon jugs
- 25mL, 50mL, 100mL, and 200mL volumetric flasks
- Test tubes
This lab experiment was designed for a lab class of non-science majors taking a food chemistry course. The students worked in pairs for the experiment. Half the class started with paper chromatography while the other half began with correlating wavelength and color if instrument access is limited. To decrease the overall time of the experiment, the students could graph the calibration curves and complete calculations outside of class time.
Unknown Kool-aid samples for day 2 of the experiment should be diluted at least 5:1 to fall inside the calibration curve. The unknown samples used in the experiment are Kool-aid packets with only one dye.
Students are able to work with their lab partners to answer the questions throughout the laboratory. Questions (including Excel graphs) are due at the end of the second laboratory period. Also, a follow-up laboratory quiz is given the laboratory period after the experiment is completed which includes questions from both concepts and data analysis for the laboratory.