511. Ammonium Chromic Sulfate

Nomenclature

CAS number: 13548-43-1
Ammonium disulfatochromate(III); chromic ammonium sulfate.
CrH4NO8S2; mol wt 262.16.
Cr 19.83%, H 1.54%, N 5.34%, O 48.82%, S 24.46%.
NH4Cr(SO4)2.

Description and references

Prepd by crystallization from a soln contg equimolar amounts of Cr2(SO4)3 and (NH4)2SO4: Howarth in ACS Monograph Series no. 132, entitled “Chromium,” vol. 1, M. J. Udy, Ed. (Reinhold, New York, 1956) p 287; electrolytic prepn: Nishihara et al., JP 60 2164 (1960), C.A. 55, 5200e (1961).

Derivative

Dodecahydrate.

Nomenclature

Chrome alum ammonium.

Properties

Small dark-violet or violet-blue, octahedral, cubic crystals; ruby-red by transmitted light. mp 94°; loses 9H2O on melting and the remaining H2O by 300°. d25 1.72. Readily sol in water; slightly sol in alcohol. Aq soln is violet when cold, green when hot.

Use

Mordant in textile industry; in manuf of electrolytic Cr metal.