Testing Unknown Solids with Iodine

Green Talc Does not dissolve iodine beads up 

1 Blue Baking soda Dissolves liquid is color of iodine 

Safety Note This unit uses highly diluted Iodine (0.1%). which is not harmful if ingested in small quantities. Iodine, however, is considered toxic when ingested in large quantities. If a student ingests a large quantity, call your local poison control center immediately. 

1 Record Sheet 7-A Test Results Table (from Lesson 7) 1 pencil 

Put iodine labels on 15 dropper bottles and fill them with the iodine solution. Add the dropper bottles of iodine to the materials center. 

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Your students have carried out two physical tests (water drop and water mixtures) and four chemical tests (vinegar, iodine, red cabbage juice, and heat) on the unknown solids. In this lesson, they review and analyze all the data they have collected as a result of performing these tests to determine the distinctive properties of each unknown. This process provides students with the information and skills they need to solve the mystery in Lesson 12. 

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