Sodium Rhodinitrite, Na₃Rh(NO₂)₆

Sodium Rhodinitrite, Na₃Rh(NO₂)₆, is obtained in an analogous manner to the potassium salt, the original chloride solution containing about 40 grams of rhodium per litre.1 After adding the nitrite an equal volume of alcohol is added, which effects the precipitation of the salt, which may be recrystallised from water.

Sodium rhodinitrite dissolves in 2½ times its weight of water at 17° C., and in one part of boiling water. It is thus considerably more soluble than its potassium analogue. Its solution, however, does not give the reactions for rhodium, which suggests that it is a rhodinitrite, Na₃Rh(NO₂)₆, analogous to potassium cobaltinitrite.

Hydrogen sulphide slowly precipitates from solution rhodium sulphide. Mineral acids attack it, slowly in the cold, rapidly on warming. Warm hydrochloric acid converts it into sodium chlor-rhodite (vide supra), Na₃RhCl₆.18H₂O. When heated to incipient redness until evolution of gas ceases, the compound Na₂O.8RhO₂ is obtained.