The Br-Hg (Bromine-Mercury) System

Abstract

Only fragments of the Br-Hg phase diagram are known. Due to significant volatility of both component elements, the Liquidus solubility in liquid Br and Hg cannot be investigated without pressure elevation. The assessed phase diagram, presented Parts of the Br-Hg liquidus were determined in several studies. [1970Dwo] used thermal analysis, [1907Bec] and in Fig. 1, is based on work of [1970Dwo], who performed some experiments allowing presentation of the general shape [1951Jan] performed cryoscopic measurements and [1959Jan], [1974Wen], [1975Bar1], [1982Pod], [1989Pan1], of the phase relationships. Special points of the Br-Hg phase diagram are collected and [1989Pan2] determined the melting point of HgBr2. The data obtained in these works are collected in Table 2. There is in Table 1. One should remember that the system of the reactions is not complete because the composition range 3 nearly perfect agreement of the liquidus data from [1907Bec], [1951Jan], and [1970Dwo] in the vicinity of HgBr2 composito 33 at. % Hg was not investigated. Although the compound HgBr2 melts congruently, it is likely that another immiscibiltion. A correction of 3.5 8C was made to all results of [1907Bec] because of the melting point of HgBr2 accepted ity gap will be observed between pure Br and HgBr2 because immeasurably small solubility of HgBr2 in liquid Br was in this assessment. Some experiments of [1970Dwo] at the highest temperatures were certainly obtained at elevated presobserved even at 80 8C in thermal analysis experiments of [1970Dwo]. sure because Hg boils at 356.58 8C and HgBr2 sublimes at 345 8C [1989Gre], whereas a few thermal arrests of The Br-Hg system consists of the following phases: (1) L, the liquid, (2) L1 and L2, the partly miscible liquids separating [1970Dwo] were recorded at temperatures higher than these. It is quite well known to electrochemists that Hg2Br2 elecmolten Hg2Br2 from Hg liquid, (3) two (probably) line compounds Hg2Br2 and HgBr2, the first one may be present in trodeposited on a Hg electrode is not measurably soluble in liquid Hg at room temperature [1954Bou]. The solubiltwo polymorphic forms below and above 2129 8C, (4) (Hg) with unknown but certainly small solid solubility of Br in ity value ,1026 at.% Br, obtained by extrapolation of