Ferrous Sulphate Heptahydrate USP

SPECIFICATION

Description

Pale, bluish-green crystals or granules. Is odorless and is efflorescent in dry air. Oxidizes readily in moist air to form brownish yellow basic ferric sulfate.

Identification

A.     B.     1 N sodium hydroxide, solutions of ferrous salts yield a greenish-white precipitate; when shaken, the color changes rapidly to green and then to brown.

               SULFATES:

C.     D.    

E.     Hydrochloric acid produces no precipitate when added to solutions of sulfates (distinction from thiosulfates).

Solubility

Very soluble in boiling water; freely soluble in water; insoluble in alcohol.

pH

Its solution (1 in 10) is acid to litmus, having a pH of about 3.7.

Assay (on dried basis)

99.5-104.5%

Mercury 

NMT 3 µg/g

Arsenic

Max 3 ppm

Lead 

Max. 10 ppm