Precipitation mercury oxide

Synonyms Mercuric oxide, red ("Red precipitate ) Mercuric oxide, yellow ( Yellow precipitate") Mercury oxide Chemical Formula HgO (ii) Observable Characteristics — Physical State (as shipped) Solid Color Red Odor None (iii) Physical and Chemical Properties — Physical State at 15 °C and 1 atm. Solid Molecular Weight 216.61 Boiling Point at I atm. Not pertinent (decomposes) Freezing Point Not pertinent ... 

In the Journal de Physique for 1779 the French apothecary Bayen described a fulminating mercurial compd of a different kind. It was obtd by mixing 30 parts of precipitated Hg oxide(washed and dried) with 4 or 5 parts of sulfur. This mixt exploded violently when struck with a heavy hammer or on being heated on an iron plate... 

Lemery describes the preparation of the red precipitate of mercury by first dissolving metallic mercury in spirit of niter (nitric acid). The product is dried, then heated further to form the red precipitate (mercuric oxide) ... 

To a vigorously stirred suspension of 40 gm (0.138 mole) of mercuric oxide in 100 ml of water is added slowly 15 gm (0.134 mole) of A-ethyl-A -isobutyl-hydrazine. After the addition has been completed, stirring is continued for an additional hr at room temperature. The mercury and mercury oxides are then removed by filtration. The precipitate is washed with ether and the aqueous phase is extracted with ether. The ether solutions are combined and dried with anhydrous magnesium sulfate. Then the ether is distilled off. The residue is distilled at 105°-107°C (741 mm Hg) yield 5.8 gm (40%). On redistillation, an appreciable quantity of a high-boiling residue is left behind, possibly because of thermal decomposition. 

It is stated that protoxide of mercury ia occasionally adulterated -with minium or red lead, sesquioxide of iron, and powdered brick. Such substances are readily detected by heating the substance to a dull heat the protoxide of meroury sublimes, and leaves the nonvolatile matters in the crucible, or the mercurial compound maybe treated with dilute nitric add, to dissolve the mercurial oxide and should minium be present, a pace-colored binoxide of lead remains together with the other adulterants, if any be present. On adding dilute sulphuric acid to the door liquor obtained in the foregoing, a white precipitate of sulphate of lead falls, corroborative of the existence of a lead compound. 

The former is deposited in yellow crystals, mixed with sulphur when acetoxime is treated with phosphorus pentasulphide in carbon bisulphide soln. the insoluble product extracted with alcohol and the alcoholic soln. heated to boiling the compound separates from cold water in large, transparent, seemingly monoclinic prisms, melts at 146° 150° with decomposition, and is readily soluble in water, but only sparingly in alcohol, and insoluble in ether and carbon bisulphide. It decomposes carbonates, gives a colourless precipitate with lead acetate, and is decomposed by hot dilute nitric acid with separation of sulphur and formation of phosphoric acid it is also decomposed by mercuric oxide, the filtrate from the precipitated mercury sulphide giving all the reactions of phosphoric acid. 

The most common procedure for analyzing mercury in precipitation is oxidation with BrCl, prereduction with NH2OH HC1, followed by reduction of the aqueous Hg to Hg° using SnCl2. Hg is purged onto gold traps, thermally desorbed, and analyzed using CV-AFS.61516... 

Ammoniates. Repeat Experiments 3 using 6 N NH4OH instead of NaOH. Note that in every case a limited amount of reagent produces the same precipitate as NaOH, and that excess of the reagent redissolves all the precipitates except those of the mercury oxides. 

Dimethylaminophenyl 4-Fluorophenyl Tellnrinm Dichloride2 In a 250 ml flask fitted with a reflux condenser are placed 16.5 g (50 mmol) of 4-fluorophenyl tellurium trichloride, 19.0 g (50 mmol) of 4-dimcthylaminophenyl mercury acetate, and 100 ml of absolute dioxane. The mixture is heated under reflux for 8 h during which time it acquires a dark violet color. The mixture is allowed to cool to 20°, the precipitated mercury(II) chloride/dioxane adduct is filtered off, and activated charcoal is added to the filtrate which is then heated under reflux for 30 min. The mixture is allowed to cool and is then passed through a layer of aluminum oxide. The filtrate is concentrated to one-fourth of its original volume by distillation, the concentrate is diluted with 100 ml of hexane to precipitate the product which is filtered off, washed with hexane, dried, and recrystallized from propanol yield 7.2 g (35%) m.p. 145". 

Cyanides, thiocyanates, hexacyanoferrate(II)s, and hexacyanoferrate(III)s also yield ammonia under these experimental conditions. The reaction is somewhat slower for these anions up to 5 minutes may elapse before ammonia can be detected from hexacyanoferrate(II)s and hexacyanoferrate(III)s. If these are present, or are suspected as a result of the preliminary tests, particularly that with concentrated sulphuric acid, they must first be removed as follows. Treat the soda extract with excess of nitrate-free silver sulphate, warm the mixture to about 60°, shake vigorously for 3-4 minutes, and filter from the silver salts of the interfering anions and excess of precipitant. Remove the excess silver ions from the filtrate by adding excess sodium hydroxide solution and filter off the precipitated silver oxide. Evaporate the filtrate to about half bulk and test with zinc, aluminium or Devarda s alloy. If cyanides alone are present, they may be rendered innocuous by the addition of a little mercury(II) chloride solution. 

The addition of silver or mercury oxide precipitates the metal halide, leaving behind the aqueous solution, which is very reactive and is used for bleaching and sterilizing purposes. Solutions of hypohalites can be made by introducing the appropriate halogen into basic solutions (equation 113), but these will also contain some halide anions. To obtain pure hypochlorites, it is necessary to carefully neutralize pure hypochlorous acid. The most stable hypochlorites are those of Li, Ca, Sr, and Ba, although some others are also known but are not as stable, or are not sufficiently pure. 

After the reaction is finished, the insoluble silver hyponitrite Ag2N202 is precipitated with AgNOs. H2N2O2 is accessible by treating the silver salt with a solution of HCl gas in diethyl ether, or by oxidation of hydroxylamine with copper, silver, or mercury oxide. 

It was quickly realized that the mercury species to be found in greatest abundance in precipitation was ionic mercury (e.g., Fogg and Fitzgerald, 1979). Some typical values of total mercury in precipitation are shown in Table 10. Extensive databases of precipitation mercury concentrations are available from monitoring networks in the US, Canada, and Nordic countries (e.g., US Mercury Deposition Network http //nadp.sws.uiuc.edu/ mdn). The discrepancy between the dominant gas and precipitation phase species implied a process of oxidation of elemental mercury in the atmosphere and its subsequent scavenging as being a major component of the mercury cycle. Since the initial work, and partially in response to... 

Freshly precipitated mercuric oxide and the calculated quantity of dinitrophenol are boiled together in aqueous solution for sixteen hours, a lemon-yellow powder resulting which is only slightly soluble in water or alcohol, and insoluble in other solvents except pyridine. When heated witli the latter it forms a double compound which may be precipitated by the addition of ether. This derivative is dark yellow in colour and is decomposed when heated, and in aqueous solution it yields no mercury ions. When the anhydride is treated with bromine, o-bromodinitro-phenol is formed, and with dilute hydrochloric acid the chloromercuri derivative is obtained, a colourless, crystalline powder, M.pt. 182° C. with decomposition,... 

Sixty parts of freshly precipitated mercuric oxide and 50 >arts of 2 G dihydroxy-l imino-dihydropyrimidine-3-acetic add (sodium salt) in 200 parts of watx r are shaken for ten liours. The greater part of tlie rnereurie oxide dissolves. The liltrate is concentrated in vacuo and the residue treated with pure alcohol, the mercury deri ative being ])recipitated pure in a crystalline form. It is extremely solulde in water, alkalies, or carbonates, insoluble in alcohol, ether, chloroform, or bcjizene. Tlie eDm >ound has tlie constitution -... 

Note that, depending on its history, the same pure compound may display different secondary qualities the precipitate of mercury oxide is yellow as a product of calcination, it is red (the color difference is due to a difference in grain size). 

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