Ceric ammonium nitrate, Ce(NO₃)₄.2(NH₄)NO₃

Ceric ammonium nitrate, Ce(NO₃)₄.2(NH₄)NO₃, is of considerable practical importance for the preparation of pure ceria. Indeed, from the practical point of view, it is the most important of the ceric salts. Its solubility in water is as follows (in grams of salt per 100 grams of solution): -

Temp. ° C	25°	35.2°	45.3°	64.5°	85.6°
Grams of Ce(NO3)4.2(NH4)NO3	58.5	62.8	64.5	66.8	69.4

At temperatures above 60° partial reduction to cerous nitrate takes place in the aqueous solution.

It may readily be prepared by the electrolytic oxidation of cerous ammonium nitrate in a divided cell.

Ceric nitrate also forms an isomorphous series of double salts with the nitrates of the bivalent metals magnesium, zinc, nickel, cobalt, and manganese; they are of the type Ce(NO₃)₄.M(NO₃)₂.8H₂O, and must be crystallised from concentrated nitric acid. The crystals are monoclinic and isomorphous with the corresponding double thorium nitrates: -

	a	b	c	β
Ce(NO3)4.Mg(NO3)2.8H2O	1.032	1	1.586	96°43'
Ce(NO3)4.Zn(NO3)2.8H2O	0.978	1	1.339	100°0'