Powder Analysis

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What Is That White Powder?

A forensic scientist may discover powder at a crime scene. In order to determine if it is illegal or not the crime lab will identify the substance using chemistry. Take on the role of a forensic chemist to identify unknown substances.

Become a Forensic Chemist by following these procedures and filling in the Powder Analysis Chart with your results. You will need Adobe Acrobat Reader to view and print the chart.

Complete the appearance, texture, and smell activities before opening the vinegar and iodine bottles.

1. Place one-fourth teaspoon (1 ml) of the four white powders on a sheet of black construction paper. Label the powders with the white chalk or white crayon.
2. Study the powders with the magnifying glass. Examine what each powder looks like. How would you describe the powder's shape. Does it have large or small grains? Your observations should be written in the appearance column of the chart.
3. Examine the powders further by rubbing each powder between your fingers. Describe how each powder feels in the Texture column of the chart.
4. Determine if there is a smell to any of the powders. Record your findings in the Smell column of the chart.
5. Take the eyedropper and place a drop of water on each individual powder. Examine what happens? Do the powders dissolve? Is there a reaction? Write your observations in the Reaction to Water column.
6. Place one-half teaspoon (2ml) of each powder in a separate jar. Add 2 drops of iodine to each jar using the eyedropper. Record what happens in the Reaction to Iodine column. Iodine should be handled with care.

Comparing test results of substances that are known help Forensic Scientists identify unknown substances.

Try this in your classroom: After analyzing and recording results of each substance have your partner leave the area. Select and place one of the powders on construction paper and do not tell which substance it is. Invite your partner back to see if she/he can determine the powder by performing the same experiments and observations previously done. Change places so your partner can select one of the powders for you to identify. Can you correctly identify the mystery powder?

Extension: View the powders under a microscope.

4 sheets of back construction paper