Page 216 - Encyclopedia of Chemical Compounds 3 Vols

O 2-

Ca 2+ O S O

O

OTHER NAMES:
Anhydrous gypsum;
also see Overview for
synonyms of
hydrates
Calcium Sulfate
FORMULA:
CaSO 4
ELEMENTS:
Calcium, sulfur,
oxygen KE OVERVIEW
COMPOUND TYPE: Calcium sulfate (KAL-see-um SUL-fate) occurs in three
Salt (inorganic) Y forms:
STATE: F • anhydrous calcium sulfate (CaSO 4 ); the anhydrous form
Solid A of calcium sulfate is available in two forms, known as
insoluble anhydrite and soluble anhydrite;
MOLECULAR WEIGHT: C
136.14 g/mol T • calcium sulfate dihydrate (CaSO 4 2H 2 O), also known as
mineral white, terra alba, light spar, precipitated cal-
MELTING POINT: S

1460 C (2660 F) cium sulfate, native calcium sulfate, and by other
names;
BOILING POINT: 1
• calcium sulfate hemihydrate (CaSO 4 / 2 H 2 O), also known
Not applicable
as plaster of Paris and dried gypsum;
SOLUBILITY:
The physical properties of the three forms of calcium
Insoluble in water and
most organic sulfate differ somewhat from each other, but their chemical
solvents properties are essentially the same. Anhydrous calcium sul-
fate and calcium hemihydrate are fine white odorless pow-
ders or crystalline solids, while the dihydrate may occur
either as a powder or as white lumps. Both hydrates are

CHEMICAL COMPOUNDS 165