Strontium hydroxide

Strontium hydroxide, Sr(OH)2, is a caustic alkali composed of one strontium ion and two hydroxide ions. It is synthesized by combining a strontium salt with a strong base. Sr(OH)2 exists in anhydrous, monohydrate, or octahydrate form.

Strontium hydroxide
Identifiers
CAS Number
3D model (JSmol)
ChEBI
ChemSpider
ECHA InfoCard 100.038.501
EC Number
  • 242-367-1
Gmelin Reference
 847042
PubChem CID
UNII
CompTox Dashboard (EPA)
Properties
Chemical formula
 Sr(OH)2
Molar mass 121.63 g/mol (anhydrous)
139.65 g/mol (monohydrate)
265.76 g/mol (octahydrate)
Appearance prismatic colourless crystals
deliquescent
Density 3.625 g/cm3 (anhydrous)
1.90 g/cm3 (octahydrate)
Melting point 535 °C (995 °F; 808 K) (anhydrous, 375K for octahydrate)
Boiling point 710 °C (1,310 °F; 983 K) decomposes (anhydrous)
Solubility in water
 0.41 g/100 mL (0 °C)
1.77 g/100 mL (40 °C)
21.83 g/100 mL (100 °C) [1]
Solubility insoluble in acetone
soluble in acid, NH4Cl
Basicity (pKb) 0.3 (first OH–), 0.83 (second OH–)[2]
Magnetic susceptibility (χ)
 −40.0·10−6 cm3/mol
Structure
Crystal structure
 tetragonal (octahydrate)
Hazards
NFPA 704 (fire diamond)
0
1
1
Flash point Non-flammable
Related compounds
Other anions
 Strontium oxide
Strontium peroxide
Other cations
 Beryllium hydroxide
Magnesium hydroxide
Calcium hydroxide
Barium hydroxide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N verify (what is YN ?)
Infobox references

Preparation

Because Sr(OH)2 is slightly soluble in cold water, its preparation can be easily carried out by the addition of a strong base such as NaOH or KOH, drop by drop to a solution of any soluble strontium salt, most commonly Sr(NO3)2 (strontium nitrate). The Sr(OH)2 will precipitate out as a fine white powder. From here, the solution is filtered, and the Sr(OH)2 is washed with cold water and dried.[3]

Applications

Strontium hydroxide is used chiefly in the refining of beet sugar and as a stabilizer in plastic. It may be used as a source of strontium ions when the chlorine from strontium chloride is undesirable. Strontium hydroxide absorbs carbon dioxide from the air to form strontium carbonate.

Safety

Strontium hydroxide is a severe skin, eye and respiratory irritant. It is harmful if swallowed.

References
  1. Pradyot Patnaik. Handbook of Inorganic Chemicals. McGraw-Hill, 2002, ISBN 0-07-049439-8
  2. "Sortierte Liste: pKb-Werte, nach Ordnungszahl sortiert. - Das Periodensystem online" (in German).
  3. Brauer, Georg (1963). Handbook Of Preparative Inorganic Chemistry. Academic Press. p. 935.
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