Congratulations to Grazyna Zreda who solved the Chemical Mystery of the Mentos candies! To conduct this trick, two white Mentos candies are placed in separate beakers that both contain universal indicator.
I was looking for a new demonstration to initiate a discussion about polarity and related properties to use as part of an exam review. I found a video at ChemEd X (this is part of a ChemEd X subscription). It is entitled “Floating Squares – Hexane and Water” (see note below). I have placed both solutions together before, but I had not added the squares. The demonstration fulfilled my needs. I could have used the original video and muted it if I had not had hexane to demonstrate with.
Wow! A very neat experiment, called “Hydroglyphics”, published by Kim, Alvarenga, Aizenberg, and Sleeper in the Journal of Chemical Education allows you to transform a common plastic Petri dish into a unique teaching tool to demonstrate the difference between hydrophobic and hydrophilic surfaces. Check it out in the video.