Gallium dichloride, GaCl₂

Gallium dichloride, GaCl₂, prepared by heating the trichloride with excess of gallium and distilling the product in carbon dioxide, forms white, transparent crystals, melting at 164° and boiling at 535°. The liquid exhibits the phenomenon of superfusion to a remarkable degree, as, indeed, do all the halogen compounds of gallium. The vapour density at 1000° to 1100° is 4.82 (air = 1), the formula GaCl₂ corresponding to 4.86. At higher temperatures dissociation takes place, probably into GaCl and chlorine.

In moist air, the dichloride deliquesces to a clear liquid. The addition of an excess of water leads to precipitation of an oxychloride, hydrogen (and perhaps gallium hydride) being evolved.