Gallium compound, vapor pressure

Gallium(III) bromide is a hygroscopic, white solid which sublimes readily and melts at 122.5° to a covalent, dimeric liquid. The solid is ionic and its electrical conductivity at the melting point is twenty-three times that of the liquid.5 The vapor pressure of the liquid at T°K is given by the equation log p(mm.) = 8.554 — 3129/T and the heat of dissociation of the dimer in the gas phase is 18.5 kcal./mol.3 At 125° the liquid has the following properties 5,6 density, 3.1076 dynamic viscosity, 2.780 c.p. surface tension, 34.8 dynes/cm. and specific conductivity, 7.2 X 10-7 ohm-1 cm.-1 Gallium(III) bromide readily hydrolyzes in water and forms addition compounds with ligands such as ammonia, pyridine, and phosphorus oxychloride. 

An analysis was made of the published experimental and calculated values of the theimochemical constants of gallium phosphide (the standard entropy and the specific heat, the enthalpy, and the free energy of formation of diis compound) and of the equilibrium constants and vapor pressure of phosphorus. Approximate methods were used to calculate the remaining constants the specific heat was found by the Landiya method and the standard entropy was deduced from the Eastman equation and by summing the entropies of elemental group IV semiconductors. 

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