Molybdenum sulphates

Wardlaw, J. Soc. Chem. Ind., 1926, 45, 210 T. For the action of sulphur dioxide on the ohlorides of iron under various conditions and on molybdenum sulphate, see Wardlaw and Clews, he. dt. Wardlaw, Carter and Clews, lac. cit. Wardlaw and Sylvester, Trans. Ohem. Soc., 1923,123, 969. 

Molybdenum Sulphates.— Reduction of a solution of molybdic acid in sulphuric acid by means of hydrogen sulphide is stated to yield the compound M0O3.M0O0.2SO3 as a black substance, soluble in water to an unstable brown solution reduction with alcohol is said to yield soluble blue crystals of the sulphate 7MoO3.2MoO3.7SO3.aq. 

Gelatine Lead Azide (GAM)> Animal gelatine was used for crystal modification of lead azide with the addition of a small amount of molybdenum sulphate [132]. It is claimed that the product is safer in handling than usual lead azide. 

Another uranium phosphate mineral, lermontovite, has been described by Soboleva and Pudovkina. This mineral occurs as botryoidal aggregates of radial fibrous needles. The formula is apparently U3(P04)4-6H20 with some substitution of Ca and RE for the U. The material is poorly characterized. It is associated with molybdenum sulphate, marcasite, hydrous silicates and thallium ochre . This phase requires more careful characterization. 

Fertilisers For nitrates, non-molybdenum austenitic steels are satisfactory, but in the manufacture of ammonium sulphate some free acid is often present, so that evaporators and centrifugal dryer baskets in this case are generally made from molybdenum-bearing steels. For super-phosphates this has limited application. 

Discussion. Molybdates [Mo(VI)] are quantitatively reduced in 2M hydrochloric acid solution at 60-80 °C by the silver reductor to Mo(V). The reduced molybdenum solution is sufficiently stable over short periods of time in air to be titrated with standard cerium(IV) sulphate solution using ferroin or /V-phenylanthranilic acid as indicator. Nitric acid must be completely absent the presence of a little phosphoric(V) acid during the reduction of the molybdenum(VI) is not harmful and, indeed, appears to increase the rapidity of the subsequent oxidation with cerium(IV) sulphate. Elements such as iron, copper, and vanadium interfere nitrate interferes, since its reduction is catalysed by the presence of molybdates. 

With the exception of iron(II) and uranium(IV), the reduced solutions are extremely unstable and readily re-oxidise upon exposure to air. They are best stabilised in a five-fold excess of a solution of 150g of ammonium iron(III) sulphate and 150 mL of concentrated sulphuric acid per litre [approximately 0.3M with respect to iron] contained in the filter flask. The iron(II) formed is then titrated with a standard solution of a suitable oxidising agent. Titanium and chromium are completely oxidised and produce an equivalent amount of iron(II) sulphate molybdenum is re-oxidised to the Mo(V) (red) stage, which is fairly stable in air, and complete oxidation is effected by the permanganate, but the net result is the same, viz. Mo(III)- Mo(VI) vanadium is re-oxidised to the V(IV), condition, which is stable in air, and the final oxidation is completed by slow titration with potassium permanganate solution or with cerium(IV) sulphate solution. 

Large amounts of chloride, cobalt(II), and chromium(III) do not interfere iron(III), nickel, molybdenum)VI), tungsten(VI), and uranium(VI) are innocuous nitrate, sulphate, and perchlorate ions are harmless. Large quantities of magnesium, cadmium, and aluminium yield precipitates which may co-precipitate manganese and should therefore be absent. Vanadium causes difficulties only... 

Molybdenum blue method. When arsenic, as arsenate, is treated with ammonium molybdate solution and the resulting heteropolymolybdoarsenate (arseno-molybdate) is reduced with hydrazinium sulphate or with tin(II) chloride, a blue soluble complex molybdenum blue is formed. The constitution is uncertain, but it is evident that the molybdenum is present in a lower oxidation state. The stable blue colour has a maximum absorption at about 840 nm and shows no appreciable change in 24 hours. Various techniques for carrying out the determination are available, but only one can be given here. Phosphate reacts in the same manner as arsenate (and with about the same sensitivity) and must be absent. 

The following procedure has been recommended by the Analytical Methods Committee of the Society for Analytical Chemistry for the determination of small amounts of arsenic in organic matter.20 Organic matter is destroyed by wet oxidation, and the arsenic, after extraction with diethylammonium diethyldithiocarbamate in chloroform, is converted into the arsenomolybdate complex the latter is reduced by means of hydrazinium sulphate to a molybdenum blue complex and determined spectrophotometrically at 840 nm and referred to a calibration graph in the usual manner. 

Sulphuric acid is not recommended, because sulphate ions have a certain tendency to form complexes with iron(III) ions. Silver, copper, nickel, cobalt, titanium, uranium, molybdenum, mercury (>lgL-1), zinc, cadmium, and bismuth interfere. Mercury(I) and tin(II) salts, if present, should be converted into the mercury(II) and tin(IV) salts, otherwise the colour is destroyed. Phosphates, arsenates, fluorides, oxalates, and tartrates interfere, since they form fairly stable complexes with iron(III) ions the influence of phosphates and arsenates is reduced by the presence of a comparatively high concentration of acid. 

A. Molybdenum blue method Discussion. Orthophosphate and molybdate ions condense in acidic solution to give molybdophosphoric acid (phosphomolybdic acid), which upon selective reduction (say, with hydrazinium sulphate) produces a blue colour, due to molybdenum blue of uncertain composition. The intensity of the blue colour is proportional to the amount of phosphate initially incorporated in the heteropoly acid. If the acidity at the time of reduction is 0.5M in sulphuric acid and hydrazinium sulphate is the reductant, the resulting blue complex exhibits maximum absorption at 820-830 nm. 

Molybdate-strychnine reagent This reagent is prepared in two parts these are mixed just before use, since the addition of the acid molybdate solution to the strychnine sulphate solution produces a precipitate after 24 hours. Solution A (acid molybdate solution) place 30 g molybdenum trioxide in a 500 mL conical flask, add 10 g sodium carbonate and 200 mL water. Boil the mixture until a clear solution is obtained. Filter the hot solution, if necessary. Add 200 mL 5M sulphuric acid, allow to cool, and dilute to 500 mL. 

Synonym(s) Chromic acid, lead and molybdenum salt lead chromate, sulphate and molybdate molybdenum-lead chromate molybdenum orange Lead dinitrate nitric acid lead(2+) salt lead (II) nitrate plumbous nitrate Lead(2+) oxide lead monoxide litharge massicot Lead(2+) phosphate Phosphoric acid lead(2+) salt ... 

Mineral fillers and additives aluminium trihydrate (ATH), magnesium hydroxide and boron derivates are the best known but tin derivates, ammonium salts, molybdenum derivates and magnesium sulphate heptahydrate are used to varying extents and nanofillers are developing. 

To prepare molybdenum liquid for determining the phosphate ion, dissolve 50 g of ammonium sulphate in 450 ml of a 68% nitric acid solution and 150 g of ammonium molybdate in 400 ml of distilled water. Cool the second solution to room temperature and pour it into the first one with constant stirring. Bring the total volume of the solution up to one litre. In a few days, filter off the solution for the precipitate. 

It is well known that C0M0O4 is destroyed by the presence of potassium.8 The reduction of Mo(Vl) to Mo (IV) is enhanced by potassium and it is easier to reduce to Mo(IV) during sulphation. The addition of potassium leads to a monotonic decrease in the molybdenum dispersion with the impregnating amount of potassium in the oxidic state catalyst, but it is more complicated after sulphation. Potassium is well spread on the surface in both the oxidic and sulfided states. The catalytic activity for the WGSR was correlated with the potassium content of CoMoK/r-AljC. The electronic effectiveness of potassium on the catalyst is not found. 

When lubrication failure finally occurs, the surface film contains large quantities of molybdic oxide and sulphate, and very little molybdenum disulphide. Presumably the disordered nature of the products causes a volume increase, which leads to the formation of the blisters if the nature of the contact permits it. Kinner considered that blister formation was unlikely to be a cause of failure in conformal contacts because the presence of uniform loading over the surface prevents any vertical development. The same oxidation process takes place in conformal sliding, except to the extent that conformal contact inhibits oxygen access, and even if blisters are physically prevented from forming, there must be a slow increase in friction and film break-up. 

He used spectrochemical techniques to study the composition of burnished molybdenum disulphide films from preparation to eventual failure. He found that the film surface at failure contained little molybdenum disulphide but contained molybdic oxide, sulphur, sulphate and iron compounds. In the presence of antimony trioxide, however, there was preferential oxidation of the antimony trioxide to the tetroxide Sb204. On heating a mixture of molybdenum disulphide and antimony trioxide in air at 500 C and 600 C, he found by X-ray diffraction that the products were mixtures of molybdenum disulphide and antimony tetroxide. Neither molybdic oxide M0O3 nor antimony trioxide was present. When molybdenum disulphide alone was heated under the same conditions, it was almost completely converted to molybdic oxide. 

SYNS CHROMIC ACID, LEAD and MOLYBDENUM SALT CHROMIC ACID LEAD SALT with LEAD MOLYBDATE C.I. PIGMENT RED 104 LEAD CHROMATE, SULPHATE and MOLYBDATE MOLYBDENUM-LEAD CHROMATE MOLYBDENUM ORANGE... 

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