Students became chemistry sleuths in the science lab this week. In this lesson, we discussed how to identify a chemical without the use of complicated machines. Students learned that in addition to using their senses, they could also use chemical properties for identification. Each group of students was given one of six known white powders to test (baking soda, borax, salt, sugar, chalk and cornstarch) and using the data they collected from a series of 4 tests, they were then able to use their test results to identify an unknown white powder.
Working collaboratively, the students performed tests of several different properties of their white powders, including solubility and reactivity. They observed which samples dissolved in water and/or in rubbing alcohol, and which reacted with vinegar or iodine (if a substance reacted with vinegar the students observed bubbling, and if a substance reacted with iodine, it turned purple!). After pooling their results as a class, they then used the data to determine the identity of their unknown substance, which turned out to be a combination of two of the white powders already tested: baking soda and salt. Students did a great job staying focused on their experiments and collecting the data they needed to identify the unknown!