manner: CuSO 4 · 5H 2 O; CaSO 4 · 2H 2 O; and Na 2 CO 3 · 10H 2 O. (The · is read as
“with.”) When these crystals are heated gently, the water of hydration can be
forced out of the crystal and the structure collapses into an anhydrous (without
water) powder. The dehydration of hydrated CuSO 4 serves as a good example
since the hydrated crystals are deep blue because of the copper ions present with
water molecules. When this water is removed, the structure crumbles into the
anhydrous white powder. Some hydrated crystals, such as magnesium sulfate
(Epsom salt), lose the water of hydration on exposure to air at ordinary
temperatures. They are said to be efflorescent. Other hydrates, such as
magnesium chloride and calcium chloride, absorb water from the air and become
wet. They are said to be deliquescent or hydroscopic. This property explains
why calcium chloride is often used as a drying agent in laboratory experiments.
CHAPTER SUMMARY
The following terms summarize all the concepts and ideas that were introduced in
this chapter. You should be able to explain their meaning and how you would use
them in chemistry. They appear in boldface type in this chapter to draw your
attention to them. The boldface type also makes it easier for you to look them up if
you need to. You could also use the Internet search engine google.com on your
computer to get a quick and expanded explanation of these terms, laws, and
formulas.
acidic anhydride
aeration
alloy
boiling point
Brownian movement
colligative property
concentrated
critical pressure
critical temperature
crystal
deliquescent
dilute
dynamic equilibrium
endothermic
efflorescent
exothermic
heat of fusion
heat of vaporization