Students investigate 8 household white powders and classify them based on their physical and chemical properties. Using their findings, students then identify an unknown powder obtained from a crime scene to determine the suspect’s guilt or innocence. Students gain experience in the identification of chemical and physical changes, careful organization of data, and writing chemical reactions. This hands-on activity is flexible and can be modified to accommodate both high school and undergraduate courses.
Safety and disposal Students can safely complete the experiment either at home or in the lab, and all waste generated can be safely disposed of down the drain.
White household solids
- NaHCO3 (baking soda)
- CaSO4 (plaster of Paris)
- CaCO3 (chalk)
- Na2CO3 (washing soda)
- Na2B4O7 (borax)
*Adapted from: Journal of Chemical Education 2001, 78, 11, 1475
Authors: Sally Solomon, Bryan Brook, Justine Ciraolo, Shawn Daly, Leia Jackson, Maria Oliver-Hoyo, and DeeDee Allen
*The original paper includes some materials that may not be suitable for at-home experiments