What elements make magnesium sulfate

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Sulphate the salt of sulfuric acid

Sulphate is a salt of sulfuric acid. Sulfuric acid as a dibasic acid forms two series of salts: sulfates, MlSO4, and hydrogen sulfates, MlHSO4.

Main group sulphates: Alkali sulphates are easily soluble in water and very thermally stable. Sodium sulfate is an important alkali sulfate. It is used in the glass, detergent and paper industries. Sodium Sulphate Decahydrate, Na2SO4· 10 H.2O, (Glauber's salt) is used in medicine as a laxative.

The solubility of the alkaline earth sulfates decreases with increasing atomic number of

  • MgSO4 (260) about
  • CaSO4 (2.41) and
  • SrSO4 (0.113) up to
  • BaSO4 (0.002).

Calcium sulphate is sparingly soluble. Strontium and barium sulfate are practically insoluble. Alkaline earth sulfates are very thermally stable.

An important main group sulphate is lead sulphate, which is formed during the discharge reaction of the lead accumulator. It is almost insoluble in water. The formation of lead sulfate therefore serves to detect lead ions.

Another important main group sulfate is aluminum sulfate. It is used in the paper and pulp industry or for water purification. Aluminum sulfate anhydrous is a white powder. The water-containing aluminum sulfate forms colorless, needle-shaped crystals.

Subgroup sulfates: Iron (II) sulfate is formed when iron is dissolved in sulfuric acid. It crystallizes from aqueous solution as light green iron sulfate heptahydrate, FeSO4, (Iron vitriol). In dry air the hydrate weathers with loss of water and yellow-brown color (oxidation to iron (III)). The double salt with ammonium sulfate (Mohr's salt) (NH4)2Fe (SO4)26 H.2O.

Copper sulphate is formed when copper is dissolved in hot, dilute sulfuric acid when exposed to air.

Copper sulfate crystallizes from aqueous solution as blue copper sulfate pentahydrate, CuSO4 · 5 H2O. Anhydrous CuSO4 is white and easily absorbs water again, turning blue. Therefore copper sulphate can be used to detect small amounts of water, for example in alcohol.


Information on magnesium and other magnesium compounds can be found in the magnesium learning unit