Flash point data for Manganese(II) sulfate hydrate are not available; however, Manganese(II) sulfate hydrate is probably combustible.
Air & Water Reactions
Water soluble. Hygroscopic.
Manganese(II) sulfate is used to produce manganese by an electrolytic process. The compound is used for dyeing textiles; for producing red glazes on porcelain; in varnish driers; in fertilizers; and in animal feeds to provide manganese as an essential trace element.
Manganese(II) sulfate hydrate is incompatible with aluminum and magnesium.
Pink crystalline powder
Manganese(II) sulfate is prepared by prolonged heating of any manganese salt with concentrated sulfuric acid. The compound is produced commercially from pyrolusite (MnO2) or rhodochrosite (MnCO3). Either mineral is dissolved in sulfuric acid and the solution evaporated:
MnO2 + H2SO4 → MnSO4 + H2O + ½ O2
Alternatively, manganese dioxide is heated strongly with dehydrated iron(II) sulfate:
2MnO2 + 2FeSO4 → 2MnSO4 + Fe2O3 + ½ O2
Manganese(II) sulfate, prepared by methods involving evaporation of manganese salt with sulfuric acid, is the tetrahydrate, MnSO4•4H2O. The tetrahydrate on gentle heating produces monohydrate, MnSO4•H2O.
Also, manganese(II) sulfate is a by-product in the manufacture of hydroquinone. The process involves reaction of aniline with manganese dioxide in sulfuric acid, followed by the removal of quinone by steam distillation under vacuum.
2C6H5NH2 (aniline) + 5H2SO4 + 4MnO2 → 2C6H4O2 + 4MnSO4 + 2C6H4O2 + 4MnSO4(quinone)
The unreacted acid is neutralized by lime, treated with water, and the solution filtered to separate any excess MnO2 and insoluble residues. Evaporation of the filtrate yields a crude product containing about 80% MnSO4 and 15% (NH4)2SO4.
Manganese(II) sulfate also may be produced by the action of sulfur dioxide with manganese dioxide:
MnO2 + SO2 → MnSO4
Odorless pale red slightly efflorescent crystals or light pink powder. pH (5% solution) 3.7.
Crystallise it from water (0.9mL/g) at 54-55o by evaporating about two-thirds of the water. It dehydrates above 400o.