I was trying very hard to remember what the other two "classic fun-for-kids crystal growing" chemicals were and it was eating me alive.
Thank you for the answer, I still remember my alum crystals for the grade school science fair.
Thank you for the answer, I still remember my alum crystals for the grade school science fair.
Fast-forward many years, and my daughter wasn't having much luck with salt, sugar, or even copper sulfate (that one looked like a melted smurf).
I remembered my alum crystals, which she tried, and lo and behold...nothing! Desperate (on the night before the assignment was due), I remembered someone mentioning that you can make crystals with mothball flakes. We picked a bag of flakes up and heated them up in a dish, and were able to make long, beautiful crystals on the bottom of a cold glass over the heated solution.
The only problem was that as soon as we moved the glass away from the solution, the crystals evaporated, so she took a picture of the crystals as they were forming and received full marks. A happy ending, but the house smelled of mothballs for a few days!