Mercurous potassium chromate

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. 

Potassium Chlorate. .. Potassium Triiodo Mercurate(ll) Potassium Chloride Potassium Chlorate Potassium Chromate Potassium Cyanide Potassium Dichromate Potassium Ferricyanide Potassium Ferrocyanide Potassium Fluoride Potassium Formate Potassium Hydride Potassium Hydrogen Phthalate Potassium Hydroxide Potassium lodate... 

M. Groger reported potassium mercurous chromate, K2Cr04.Hg2Gr04, to be formed by the action of a soln. of mercurous nitrate, containing as little free nitric acid as possible, on a sat. soln. of potassium chromate. After shaking for a couple of weeks, the solid is separated by a suction filter, and dried on a porous tile, "flie brownish-yellow product decomposes when melted and when treated with water it furnishes basic mercurous chromate. 

F. M. Littersoheid added ammonia to a soln. of potassium dichromate, mixed with an excess of mercuric chloride, in the cold until the liquid had an alkaline reaction and obtained dimercuriammanium chromate, (NHg2)2Cr04.2H20. The same product was obtained by adding an excess of ammonia to a cold soln. of mercuric chloride, and then adding a soln. of potassium chromate or dichromate. The lemon-yeUow precipitate gave off no water when heated for many hours at 100° it is virtually insoluble in water, and in a cold 10 per cent. soln. of ammonia — free from ammonium salts. The moist salt dissolves in soln. of ammonium salts. 

S. Lowenthal described mercuric amidochromate, Hg3NH2(Cr04)2 and M. Groger said that potassium mercuric chromate is not produced by treating mercuric nitrate or chloride as in the analogous process for the mercurous salt, but rather yields a basic chromate which adsorbs potassium chromate. 

J. A. Atanasiu 1-2 found that in the electrometric titration of soln. of mercurous nitrate and potassium chromate the curve shows a break corresponding with... 

White precipitates are formed when a 1% solution of cusparine is treated with phosphotungstic, phosphomolybdic or tannic acids, or with mercuric chloride or potassium mercuri-iodide. Picric acid, platinic chloride or potassium chromate give yellow precipitates, auric chloride or potassium bismuth iodide brown, and potassium ferrocyanide bluish-white (36). By treating a solution of cusparine hydrobromide with bromine water, a series of bromocusparine polybromides is obtiuned(38). 

One or two drops of the acidic test solution is saturated with potassium chloride and shaken with one or two ml of n-butyl alcohol. One drop of the alcohol solution is treated on the spot plate with a drop of a 1 % solution of a-naphthylamine in w-butyl alcohol. A violet color develops after 1-3 minutes Idn, Limit 1 y Au). Mercurous salts, chromates, and other oxidants interfere, and likewise alkali cyanide. 

Yellow mercuric chromate results from the reaction of neutral or acetic acid solutions of mercury nitrate or acetate with potassium chromate. However, large quantities of alkali acetate prevent this precipitation. The interference is due to the formation of complex mercury acetate with consequent reduction of the Hg+ concentration to such an extent that the solubility product of HgCr04 is not reached. However, the slight concentration of Hg+2 in the yellow solution is adequate to react with solid AgCN to produce water-soluble, undissociated Hg(CN)a and Ag+ ions. The latter combine with the CrO - ions present to 3rield water-insoluble red-brown silver chromate. 

Reagent Mercurynitrate (or acetate)-potassium chromate solution. Several ml of a 5 % aqueous solution of mercuric nitrate or acetate are made acidic with dilute acetic acid and 2 g of sodium acetate are added, followed by several drops of a potassium chromate solution. Should a slight precipitate appear, it can be removed by filtering or centrifuging. The clear yellow reagent is stable. 

The classical zinc-corrosion inhibitor has been mercuric or mercurous chloride, which forms an amalgam with the zinc. Cadmium and lead, which reside in the zinc alloy, also provide zinc anode corrosion protection. Other materials like potassium chromate or dichromate, used successfully in the past, form oxide films on the zinc and protect via passivation. Surface-active organic compounds, which coat the zinc, usually from solution, improve the wetting characteristic of the surface unifying the potential. Inhibitors are usually introduced into the cell via the electrolyte or as part of the coating on the paper separator. Zinc cans could be pretreated however, this is ordinarily not practical. 

Copper sulfate Ferric chloride 50% aq. sol n Ferrous chloride 50% aq. sol n Lithium chloride >30% aq. sol n Mercuric chloride sat d aq. sol n Potassium acetate sat d aq. sol n Potassium carbonate Potassium chromate sat d aq. sol n Potassium iodide... 

Occluded hydrogen is more reactive chemically than the normal gas. Hydrogenated palladium precipitates mercury and mercurous chloride from an aqueous solution of the dichloride, without any evolution of hydrogen. It reduces ferric salts to ferrous potassium ferricyanide to ferrocyanide chlorine water to hydrochloric add iodine water to hydriodic acid 2 chromates to chromic salts ceric to cerous salts whilst cupric, stannic, arsenic, manganic, vanadic, and molybdic compounds are also partially reduced.3... 

The conversion of carbon monoxide to carbon dioxide is also brought about by the action of other oxidising agents as silver oxide, potassium permanganate, iodic acid, chromic acid, mercuric chromate, etc. 

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