Chromic Nitrate, Cr(NO₃)₃

Chromic Nitrate, Cr(NO₃)₃.9H₂O, obtained by warming nitric acid with excess of chromic hydroxide (this giving a basic salt) and crystallising after the addition of a sufficient excess of nitric acid, forms purple rhombic prisms, melting at 36.5° C. and soluble in alcohol. The salt decomposes at 100° C.

More recent investigations have shown that when strongly heated chromic oxide (which, contrary to common statements, is not entirely insoluble in acids) is dissolved in hot concentrated nitric acid of density 1.4, the hydrate Cr₂(NO₃)₆.15H₂O crystallises on cooling. The dark brown crystals are prismatic:

a:b:c = 1.4250:1:1.1158; β = 93° 10'.

In contact with dry air water is lost, the residue having the composition Cr₂(NO₃)₆.9H₂O. Violet crystals of the hydrate with 15H₂O, melting at 100° C., have been prepared.

Two basic nitrates, Cr(NO₃)₂OH and Cr(NO₃)(OH)₂, are known as green amorphous substances.

The chloronitrates, Cr(NO₃)₂Cl and Cr(NO₃)Cl₂, have been prepared, together with the sulphatonitrate, Cr(NO₃)SO₄.