As part of the investigation of a crime scene, detectives note that a white powder is found at the location. Even though they have their suspicions, chemical and physical analyses must be performed to determine the identity of the powder. That’s where the crime scene technicians take over.
In this experiment, students analyze a white power by employing laboratory techniques similar to those practiced by forensic scientists. Students use Vernier technology to analyze the physical and chemical properties of the powder in order to determine its composition: they measure the melting point of the powder with the Go Direct® Melt Station and the pH and conductivity of solutions of the white powder using the Go Direct® pH Sensor and Go Direct® Conductivity Probe. Students also observe chemical reactions of the powder with iodine and acidified iron(III) ion solutions. After comparing the physical and chemical properties of the mystery powder to known chemicals provided by the teacher, students report their observations and conclusions. Note that this experiment can also be done with LabQuest versions of the sensors.