Mercury, forms

At ordinary temperatures, mercury is stable and does not react with air, ammonia (qv), carbon dioxide (qv), nitrous oxide, or oxygen (qv). It combines readily with the halogens and sulfur, but is Htde affected by hydrochloric acid, and is attacked only by concentrated sulfuric acid. Both dilute and concentrated nitric acid dissolve mercury, forming mercurous salts when the mercury is in excess or no heat is used, and mercuric salts when excess acid is present or heat is used. Mercury reacts with hydrogen sulfide in the air and thus should always be covered. 

Mole Ratios and Weights of Trifluoromethyl Mercurials Formed... 

Compounds tend to be covalent. Metals form complex ions and their oxides are only weakly basic. Mercury forms no hydride. 

Thiols are easily oxidized to disulfides in solution, but this reaction occurs only very slowly at most electrode surfaces. However, use can be made of the unique reaction between thiols and mercury to detect these compounds at very favorable potentials. The thiol and mercury form a stable complex which is easily oxidized, in a formal sense it is mercury and not the thiol which is actually oxidized in these reactions. For the LCEC determination of thiols a Au/Hg amalgam electrode is used Using a series dual-electrode both thiols and disulfides can be determined in a single chromatographic experiment... 

Mercury forms amalgams with numerous metals. Usually, this conversion is very exothermic, therefore it can present risks the reaction can become violent if a metai is added too quickly into mercury. Accidents have been described with caicium (at 390°C), aluminium, alkali metals (lithium, sodium, potassium, rubidium) and cerium. Some of these alloys are very inflammable, in particular the Hg-Zn amalgam. 

Methyl mercury formed in the reaction was also measured gas chromato-graphically in benzene extracts of the aqueous phase [82]. 

Selenium lessens the toxicity of divalent mercury in animals, the protection being less at continuous mercury exposure. Selenium has been found to affect the distribution of mercuric mercury in mice [134], rats [135], rabbits [136, 137] and pigs [ 138]. Mercury forms a mercury-selenium protein complex with selenium with little biological activity [139]. Mercury is thus retained longer in the blood, liver and spleen and as a consequence lessens accumulation in the kidney. In fish, selenium pretreatment probably retarded mercury uptake rather than promoting mercury excretion [140]. 

Why does water form a concave meniscus in a tube, while mercury forms a convex meniscus ... 

Mercury forms alloys, called amalgams, with other metals such as gold, silver, zinc, and cadmium. It is not soluble in water, but will dissolve in nitric acid. It has a high electric conductivity, making it useful in the electronics industry. However, unlike most other metals, it is a poor conductor of heat. Because of its high surface tension, it does not wet the surfaces that it touches. This characteristic also accounts for its breakup into tiny droplets when poured over a surface. If spilled, it should not be collected with bare hands, but with a thin piece of cardboard to scoop it up. 

In the oxidation of hydroxylamine by silver salts and mercurous salts, the nature of the reaction product apparently depends upon the extent to which catalysis participates in the total reaction. This is illustrated by some results obtained with mercurous nitrate as oxidizing agent. The reaction is strongly catalyzed by colloidal silver, and is likewise catalyzed by mercury. The reaction of 0.005 M mercurous nitrate with 0.04 M hydroxylamine at pH 4.85 proceeds rapidly without induction period. The mercury formed collects at the bottom of the vessel in the form of globules when no protective colloid is present, so the surface available for catalysis is small. Under these conditions the yield is largely nitrous oxide. Addition of colloidal silver accelerates the reaction and increases the yield of nitrogen. Some data are given in Table III. 

Ammonium thiocyanate reacts with several metal ions including copper, silver, zinc, lead, and mercury, forming their thiocyanate precipitates, which may be extracted into organic solvents. 

Potassium hydroxide is produced commerically by electrolysis of a saturated solution of potassium chloride in brine using mercury cells consisting of a titanium anode and mercury cathode. Potassium reacts with mercury forming the amalgam which, on treatment with water, forms potassium hydroxide and hydrogen. 

Tellurium forms many sulfides and oxysulfides. The metal reacts with sulfides of zinc, cadmium, or mercury, forming tellurium sulfide ... 

The next step away from the traditions of antiquity involved the addition of a third principle to Jabir s sulphur and mercury salt. Whereas the first two were components of metals, salt was considered an essential ingredient of living bodies. In this way alchemical theory became more than a theory of metallurgy and embraced all the material world. The three-principle theory is generally attributed to the Swiss alchemist Paracelsus (1493-1541), although it is probably older. Paracelsus asserted that sulphur, salt, and mercury form everything that lies in the four elements . 

Metals more electronegative than magnesium, like beryllium, zinc, cadmium and mercury, form useful reagents for specific purposes, but the metals themselves are not sufficiently active to form organic derivatives under normal laboratory conditions and are unwanted in the environment since they are toxic. Aluminum compounds are useful for industrial purposes, but their use in the laboratory is insignificant in comparison with Grignard reagents. 

We can, at this point, consider two well-known examples of dissociation of compounds At a pressure of one atmosphere, mercury forms an oxide below 300°C, but above this temperature the compound decomposes, while at lower oxygen pressures the decomposition temperature is lowered. Iodine atoms form iodine molecules at low temperatures, while at high temperatures the... 

Mercury forms a convex meniscus with glass rather than the concave meniscus shown in Figure 8.18. What does this tell you about the cohesive forces between mercury atoms versus the adhesive forces between mercury atoms and glass Which forces are stronger ... 

Mercury has the electronic configuration (Xe)4/145d106s2. The first three ionization potentials are 10.43, 18.65 and 34.4 eV, therefore under chemically significant conditions no more than two electrons are removed from the mercury atom. Only one complex of mercury (III), with d9 configuration and a half-life of 5 s at -78 °C, has been synthesized. The synthesis involved electrochemical oxidation of Hg(l,4,8,ll-tetraazacyclotetradecane)(BF4)2 in propiononitrile solution.11 In contrast to most other metals mercury forms polycations, e.g. Hgf+, Hgf+ or Hg3+. 

Mercury forms a unique series of catenated polyatomic cations Hgj + that can be considered as complexes having monatomic Hg° as a ligand. These cations are the subject of Section 11.3. 

The demercuration of these cyclic mercurials is fraught with more problems than analogous mercurials formed by intermolecular processes. Alkaline sodium borohydride is once again the most common reducing agent, but elimination to the starting unsaturated alcohol is not unusual. The extent of elimination varies with the mercury ligand, the pH and the solvent used.434 Phase transfer approaches offer advant-... 

Mercuric nitride of undetermined composition was stated by R. Threlfall to be formed as a brown film by tbe action of nitrogen on mercury wben the gas under diminished press, is under the influence of an electric discharge and-R. J. Strutt found that activated nitrogen reacts with mercury, forming a nitride. F. Fischer and F. Schroter also prepared the nitride by the process indicated in connection with Fig. 11. O. Flasehner found that scarcely any hydroxylamine is reduced by the mercury cathode. 

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