Mercuric thiocyanate

Chloride. Chloride is common in freshwater because almost all chloride salts are very soluble in water. Its concentration is generally lO " to 10 M. Chloride can be titrated with mercuric nitrate. Diphenylcarbazone, which forms a purple complex with the excess mercuric ions at pH 2.3—2.8, is used as the indicator. The pH should be controlled to 0.1 pH unit. Bromide and iodide are the principal interferences, whereas chromate, ferric, and sulfite ions interfere at levels greater than 10 mg/L. Chloride can also be deterrnined by a colorimetric method based on the displacement of thiocyanate ion from mercuric thiocyanate by chloride ion. The Hberated SCN reacts with ferric ion to form the colored complex of ferric thiocyanate. The method is suitable for chloride concentrations from 10 to 10 M. 

Merkuri-jodid, n. mer curic iodide, mercury (II) iodide, -nitrat, n. mercuric nitrate, mercury-(II) nitrate. -oxyd, n. mercuric oxide, mercury (II) oxide, -rhodanid, n. mercuric thiocyanate, mercury(II) thiocyanate, -salz, n. mercuric salt, mercury (II) salt, -sulfati n. mercuric sulfate, mercury (II) sulfate, -sulfidt ti. mercuric sulfide, mercury (II) sulfide. -sulfozyamd, n. mercuric thiocyanate. 

Mercury (Mercuric) Sulfocyanate (Mercuric thiocyanate, Mercuric rhodamide). Hg(SCN)2, mw 316.77, white powd mp (decompn), poisonous si sol in w (0.07g/100g at 25°), sol in ale and in NH3 NH4 salts. Can be prepd by pptn of Hg nitrate with Amm sulfocyanate and subsequent soln in a large quant of hot w, followed by crystn. Used in prepn of Pharaoh s Serpent and other fireworks (Ref 4)... 

Chlorine at the percentage level at which it occurs in sea water is usually determined by classical procedures using standard silver nitrate as the titrant and potassium chromate indicator, or alternatively by the mercuric thiocyanate procedure using dithizone as indicator. As large dilutions of the original sample are involved in these analyses, it is essential to use grade A glassware and take all other suitable precautions, such as temperature control. 

Drying, usually by physical methods, is one of the most common unit operations in both laboratory or industrial scale process chemistry, and since heating is usually employed to remove volatiles, thermally unstable materials may decompose if overheated. As a light-hearted example, when a faulty oven thermostat led to overheating of mercuric thiocyanate, a monstrous Pharaoh s serpent resulted. Drying moist cadmium propionate in an electric oven led to explosive ignition of the diethyl ketone vapour produced as an unforeseen by-product. Drying 3,5-dinitro-2-toluamide had more serious consequences. 

Gold, a mixt of aureus azidodithiocarbonate azidocarbondisulfide bulky wh fibrous ppt which changes to om on standing Lead, Pb(SCSN3)a, It grn-yel crysts, fairly stable but may det under si mechanical shock Mercuric, Hg(SCSNj)a silky ppt which undergoes spontaneous thermal decompn at RT, yielding mercuric thiocyanate. This salt may det violently under si mechanical shock... 

Disulphur Dithiocyanate, S (SCN)2, is formed 3 by the interaction of sulphur chloride and a metalliclthiocyanate, the best and most uniform results being obtained when mercuric thiocyanate is used. Chloroform or carbon tetrachloride forms a suitable solvent if the product is only required in solution, since these do not dissolve mercury salts if the compound is to be isolated, carbon disulphide is the required solvent. Disulphur dithiocyanate forms colourless crystals which melt at —3-3° C., forming a viscous, yellow, odourless liquid, which is somewhat unstable. On cautious heating it becomes dark yellow, then red, and finally detonates. It is hydrolysed by water according to the equations ... 

An aqueous solution of thioeyanic acid may be prepared by the decomposition of either silver or mercuric thiocyanate with hydrogen sulphide, or by decomposing barium thiocyanate with an equivalent quantity of sulphuric acid. It may also be obtained by distilling... 

Mercuric thiocyanate, which is formed as a white precipitate when mercuric nitrate and potassium thiocyanate solutions are mixed, is soluble in excess of either solution. When dried, this salt is inflammable, forming a voluminous ash known as Pharaoh s serpents. By the interaction of a mercuric salt with ammonium thiocyanate and thio-carbamide in acetic acid solution in the presence of an oxidising agent, or by the action of hydrogen sulphide on mercuric thiocyanate, the phototropic compound HS.Hg.CNS is obtained.6... 

While the fumes from burning mercuric thiocyanate are offensive because of their sulfur dioxide, the small amount of mercury vapor which they contain probably presents no serious danger. The possibility, however, that children may swallow the pellets, with fatal consequences, is a real hazard. For this reason, the sale of mercury snakes has been forbidden by law in many states, and black non-mercury snakes, which are essentially non-poison-ous, have come into general use. 

Chloride ion reacts with mercuric thiocyanate forming unionized mercuric chloride, liberating thiocyanate ion (SCN ). The liberated thiocyanate ion reacts with Fe3+ to form a highly colored ferric thiocyanate. These reactions are shown below ... 

Chloride. The pattern of flow for this method is depicted in Fig. 19. The method is based on a modification proposed by Zall et al. (Z1). In this method, chloride ion in acid solution containing ferric ions displaces thiocyanate ion from mercuric thiocyanate. The thiocyanate liberated reacts with excess ferric ions to form the red ferric thiocyanate (FeSCN) + + complex. The reaction is sensitive to the nature and amount of acid present. The presence of bromide would interfere with the results. 

SYNS BIS(THIOCYANATO)-MERCURY MERCURIC SULFOCYANIDE MERCURIC SULFOCYANATE, solid (DOT) MERCURIC THIOCYANATE MERCURIC THIOCYANATE, soUd (DOT) MERCURY... 

These comprise, on the one hand, easily combustible substances such as charcoal, sulphur, antimony sulphide, resins, and tar and on the other hand, they include substances which readily give up oxygen and support combustion, such as saltpetre (potassium nitrate), and potassium chlorate or other chlorates. A third category includes those substances used for the various colour effects (barium strontium, copper, and other salts), and also finely divided metals, and coarse particles of charcoal to cause sparks and showers of fire ( golden rain and the like). Other substances are sometimes used to decrease the rate of burning and to increase brilliance (r.g. mercurous chloride and mercuric thiocyanate). 

Designation of Hazardous Substances- List of hazardous substances, Table 116.4 (mercuric cyanide, mercuric nitrate, mercuric sulfate, mercuric thiocyanate, mercurous nitrate) Yes 40 CFR 116.4 EPA 1978a... 

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