Wednesday, November 28, 2007

Crystal Garden Day 1 (if we're lucky)

My next Hands-On Learning column for Home Education Magazine will be a crystal-growing project, and there are several versions I want to try. The one we started today comes from The Joy of Chemistry and uses Mrs. Stewart's Bluing. (You can also find the directions, an explanation -- and anything else you ever wanted to know about this old-fashioned, non-toxic laundry product -- on their website.)

We combined aspects of both sets of directions. Per JoC, we used an ordinary kitchen sponge, cut into cubes, as the base. But we left out the ammonia they recommend to see if it would work without, since MSB's website said it was helpful but not necessary. The sponge bits were sprinkled with water, salt and bluing.

As you can see, it really is BLUE. Prussian Blue, to be exact. According to Wikipedia, the chemical formula of PB is Fe7(CN)18(H2O)x where 14 ≤ x ≤ 16.

The PB is insoluble. The Mrs. Stewart's liquid is not a solution, but a colloidal suspension in which very tiny particles of the dye are floating. These small crystallites serve as seeds for the salt crystals that (hopefully) will be growing over the next few days.

Hah! I love it when I sound like I know what I'm talking about!

1 comment:

Alan said...

Cool beans!

I just picked up some Mrs. Stewart's Bluing this morning while confirming my suspicions that the crystal growing project in Cool Chemistry Concoctions had a potential problem: It simply calls for "liquid fabric whitener" without explanation or caution creates a risk of someone trying this with bleach ("it whitens fabric!") and mixing chlorine with ammonia.

Your approach strikes me as much safer.

I look forward to your updates - I really like your blog.