Mercury selenite

Also mercury(II) selenite is polymorphic and two new modifications, p-HgSe03 and y-HgSe03, have been recently described.134 They show the mercury atoms in sevenfold coordination of oxygen atoms, and the [I Ig07] polyhedra are linked by the pyramidal selenite ions. A remarkable and unusual mercury selenite is the mixed valent compound (HgSe03)3E[gSe.134 As a characteristic feature, the crystal structure contains [Hg3Se] pyramids with distances Hg Se of 2.489 A. 

Sapozhnikov and Markovskii measured at 298.15 K the enthalpy of dissolution of a number of zinc, cadmium, and mercury selenites in mineral aeid in a calorimeter. Sulphuric acid (aq, 1 50) was used for the zinc and cadmium compounds, while hydrochloric acid (aq, 1 35) was used for the mercury salts. The experimental details are few and... 

Table A-53 Measured enthalpies of dissolution of zinc and cadmium selenites in H2S04(aq, 1 50) and mercury selenites in HCl(aq, 1 35). The enthalpies of formation have been estimated from these data. The uncertainties stem from the original publication. The data for the compounds provided with an asterisk are given for information only as they do not seem to form under normal aqueous conditions cf. phase diagram studies reported in Chapter V).

SAP/MAR] Sapozhnikov, Y. P., Markovskii, L. Y., Composition and some properties of mercury selenite, Zh. Neorg. Khim., 10, (1965), 1399-1402, in Russian, English translation in [65SAP/MAR2]. Cited on page 285. 

Table A-53 Measured enthalpies of dissolution of zinc and cadmium selenites in H2S04(aq, 1 50) and mercury selenites in HCl(aq, 1 35). 491...

H202[g] HYDROGEN PEROXIDE (GAS) 797 HgSe03 MERCURY SELENITE 834... 

Sodium selenite has also been incorporated into styrene—butadiene mbber and used in a pellet form which results in the slow release of selenium into water. These pellets have been placed in lakes in Sweden which have fish contaminated with mercury owing to high levels of that element in the water. The selenium released by the pellets reacts with mercury to form insoluble, heavy mercury selenide which setties to the lake bottom and removes mercury from the ecosystem (126). 

The properties of anodic layers of HgS formed on mercury in sulfide solutions have been investigated in comparison with anodic sulfide layers of cadmium and bismuth. Also, the electrochemistry of mercury electrodes in aqueous selenite solutions has been studied (see Sect. 3.2.1). The problem with the presence of several cathodic stripping peaks for HgSe in acidic Se(IV) solutions has been addressed using various voltammetric techniques at a hanging-mercury-drop electrode [119]. 

A Cd compound Cd3(Se03)2(Se04), with both selenite and selenate, has been presented. The 3-D network with channels running along the b axes in P2 (Z = 2) contains three independent CdO, polyhedra (x = 6, 8), three independent Se03 pyramids, and one Se04 tetrahedron.294 It should be mentioned that this compound is isotypic with the analogous mercury compound.295... 

Klaverkamp, J.F., D.A. Hodgkins, and A. Lutz. 1983a. Selenite toxicity and mercury-selenium interactions in juvenile fish. Arch. Environ. Contam. Toxicol. 12 405-413. 

Take mercury, fix it with the (metallic) body of magnesia or with the (metallic) body of stimmi from Italy, or with sulphur apyre (native sulphur), or with aphreselinon (selenite), or burned limestone, or alum of Melos, or with arsenicon or what you will. Place the white earth (so prepared) upon copper (x >s, copper or bronze), and you will have copper without shadow (brilliant). Add yel-... 

Regarding this selenium I have heard different opinions. One is that it is acting as an antagonistic agent, immobilizing for instance mercury. It may immobilize also cadmium, because the selenites in question are quite insoluble. We know that in lakes where we have higher selenium content there is less mercury in the fish. This is of course not conclusive, but that may be an idea... 

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