Mystery powders in Grade 8 Science class

Grade 8 just learned about characteristic and non-characteristic properties of matter and how the characteristic properties help us to identify a substance.

In this lab, they observed the behavior of 4 common substances (baking soda, ascorbic acid, cornstarch and baking powder) when reacting with water, vinegar, iodine and bromothymol blue. They listed out the unique properties of these four powders while reacting with the liquids.

They were then given 3 mystery powders labeled x, y, and z (each of which could be either one of the 4 known substances or a combination of them). They tested the mystery powders the same way and compared their behavior with that of 4 known powders to draw a conclusion in identifying which substance was it.

This exercise was to appreciate how every element present in nature has their own unique set of properties and how it can be used to identify what an unknown substance is.


By Mrs. Sharavanan, MS Science teacher