REED COLLEGE SCIENCE OUTREACH PROPERTIES OF MATTER

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Lesson Eight- Mystery Powders 3
Objectives
o Students will use their knowledge of physical and chemical properties to identify
mystery powders.
Lesson Background- Properties of Matter Review
Today the students will use all the information they have learned about the physical and
chemical properties of matter to identify mystery powders. Students should already
know the following:
• Physical properties include characteristics that are easily seen (or felt) such as
color, size, shape, magnetism, physical state, etc.
• Chemical properties describe how atoms and molecules react with each other.
For this activity students will need to remember the signs of a chemical reaction
(color change, formation of a new gas, liquid, or solid, temperature change, etc.).
Activity overview
Students will make observations to determine the unidentified powders’ physical
properties and then conduct a few simple tests to determine some of the powders’
chemical properties.
Physical properties: All the powders are similar in color and composition (white
powders), but students will be able to notice slight differences. For example, milk
powder has a slight cream tinge, salt is actually made up of tiny square crystals, and
detergent is made up of differently sized particles.
Vinegar Test: This test will be able to identify substances that contain carbonate,
which will react with the vinegar to create carbon dioxide gas bubbles. These
substances will include baking soda, baking powder, Alka-Seltzer, & detergent.
Iodine Test: Iodine reacts with starch to form a blue/black compound. Detergent and
milk powder will also react and eventually cause the color of the iodine to fade.
Cabbage Juice Test: Finally, students will test the pH of the powders with cabbage
juice.
After the students have collected data on all of their powders, they should be able to use
these clues to identify each mystery powder.
3 Adapted from: “Lost Labels,” Chemistry in the K-8 classroom, OMSI, 2007.