HYDRATES
redline.gif (117 bytes)

PART B

The picture on the left has three piles of Dryerite, CaSO4, a drying agent. The Calcium Sullfate on the two end piles has been coated with a little CoCl2. What does the picture tell us?

The color of Cobalt chloride depends on temperature and relative humidity

The hexahydrate is magenta CoCl2.6 H2O
The dihydrate is a purple color CoCl2.2 H2O
The anhydrous salt is a sky blue color CoCl2

The pile on the left has been exposed to humidity whereas that on the right has not.
BUT.....What about the pile in the middle?
You can't tell by looking at it!

But...
if you had added a few pieces of "Indicating Drierite", you could have easily seen the effect of exposure to humidity.  In the picture on the left,  the pile on the left has been exposed to humidity whereas the pile on the right has not.

R.W.Kluiber 5/26/00