A commercial for a well known cleaning powder says that it "shakes out white, then turns blue" what type of reaction os occuring? what compound can one use to produce this effect?

Answer 1

Probably a hydration reaction in which the dry material is one color and the "wet" material is another. I think CoCl2 may do that under the right conditions but the CoCl2 hydrate I've seen is blue when dry and pink when wet.

Answer 2

I just did this lab... I don't know the coumpound, but its Comet the cleaner... and it is a hydration reaction... ^_^