GALLIUM(III) NITRATE OCTAHYDRATE

Purification Methods

Recrystallise the nitrate from H2O (solubility is 295g/100mL at 20o). It forms a white deliquescent, colourless powder soluble in H2O, absolute EtOH and Et2O. It loses HNO3 upon heating at 40o. Addition of Et2O to a warm ethanolic solution (40-50o) of Ga(NO3)3 9H2O precipitates Ga(OH)2NO3.Ga(OH)3.2H2O. If the salt has partly hydrolysed, dissolve it in conc HNO3, reflux, dilute with H2O and concentrate on a sand bath. Wash the solid several times by adding H2O and evaporating until there is no odour of acid. Dilute the residue to a Ga concentration of 26g/100mL. At this concentration, spongy Ga(NO3)3.xH2O separates from the viscous solution. After standing for several days the crystals are collected and dried in a stream of dry air first at room temperature, then at 40o. Dehydration is complete after 2 days. Recrystallise it from H2O and dry it at water pump vacuum at room temperature. [Reimmann & Tanner Z Naturforsch 20B 71 1965, D.nges in Handbook of Preparative Inorganic Chemistry (Ed. Brauer) Academic Press Vol I p 856 1963.]