Strontium sulfate

Physical Properties

White crystalline powder; orthorhombic crystals; refractive index 1.622; hardness 3.3 Mohs; density 3.96 g/cm3; melts at 1,605°C; very slightly soluble in water 0.014 g/100mL at 30°C; soluble in alkali chloride solutions; slightly soluble in alcohol; insoluble in alkalis.

Occurrence and Uses

Strontium sulfate occurs in nature as mineral celestite, which is the principal ore of strontium. The sulfate is the starting material for producing strontium metal and practically all its salts. The sulfate also is used in pyrotechnics and in ceramics.

Production

Strontium sulfate occurring in nature as celestite is mined from its natural deposits. Also, the sulfate can be made by reacting strontium oxide, hydroxide, or carbonate with dilute hydrochloric acid:
SrO + H2SO4 → SrSO4 + H2O
SrCO3 + H2SO4 → SrSO4 + CO2 + H2O

Description

Strontium sulfate has the molecular formula of SrSO4 and the molecular weight of 183.6842 g/mol. It can be prepared by the reaction of sodium sulfate and strontium chloride:
Na2SO4+SrCl2?SrSO4+2NaCl
Strontium sulfate occurs in nature as “celestite” and is mined from its natural deposits. Also, the sulfate can be made by reacting strontium oxide, hydroxide, or carbonate with dilute hydrochloric acid:
SrO+H2SO4?SrSO4+H2O
SrCO3+H2SO4?SrSO4+CO2+H2O
No hydrates are known.Its hardness is 3.3 Mohs. It melts at 1608°C. Its solubility in water is 0.015 g/100 ml at 25°C and 0.014 g at 35°C. It is insoluble in ethanol and acetone, but slightly soluble in acids and alkalis. It is soluble in alkali chloride solutions. The heat of formation, △H_f, is –1453 kJ/mol with an entropy value, S0, of 117.0 J/mol K. Its Mohs Hardness is 3.0–3.5. A water solution has a pH of 7.5. Its specific gravity ranges from 3.8 to 4.0 g/cm3.Pure strontium sulfate precipitate consists of single crystals, about some tens of microns long, with distinctly visible growth steps. Crystals grown with polyvinyl sulfonate in stirred solutions show a striking change of habit: they are sponge-like structures, composed of minute crystallites, of size in the nanometer range. Crystallized strontium sulfate is utilized by a small group of protozoa as a main constituent of their skeleton. It is sometimes used to impart iridescence to glass and pottery glazes or used as a fining agent in crystal glass.
There is very little demand for this salt in industry. It is available in limited quantities commercially.

Chemical Properties

Milky white powder

Uses

Widely applied in the manufacturing of Barium Salts, pigments, special glass, printing inks, paints, filler for textiles, linoleum, paper, rubber, base for color lakes, as pigment and white lead substitutes.

Uses

Strontium Sulfate combined with Bi-2212 creates a superconductor.

Uses

In ceramics, pyrotechnics.

Definition

strontium sulphate: A white solid,SrSO₄; r.d. 3.96; m.p. 1605°C. It canbe made by dissolving strontiumoxide, hydroxide, or carbonate in sulphuricacid. It is used as a pigment inpaints and ceramic glazes and to providea red colour in fireworks.

Flammability and Explosibility

Non flammable