Chromates strontium

Strontium Chromate. Strontium chromate [7789-06-2] SrCrO, is made by precipitation of a water-soluble chromate solution using a strontium salt or of chromic acid using a strontium hydroxide solution. It has a specific gravity of 3.84 and is used as alow toxicity, yellow pigment and as an anticorrosive primer for zinc, magnesium, alurninum, and alloys used in aircraft manufacture (8) (see Corrosion and corrosion control). 

The classical analytical method of deterruination of barium ion is gravimetric, by precipitating and weighing insoluble barium sulfate. Barium chromate, which is more insoluble than strontium chromate in a slightly acidic solution, gives a fairly good separation of the two elements. 

Stibine, see Antimony hydride Stoddard solvent Strontium chromate Strychnine Styrene, monomer Subtilisins (proteolitic enzymes as 100% pure crystalline enzyme)... 

To be effective, there must be a certain minimum concentration of inhibitor at the interface to be protected. Therefore, there must be sufficient inhibitor in the primer, and these inhibitors need to be soluble enough in water to enable transport of inhibitor to the oxide surface as water permeates the adhesive joint. However, too high of a solubility will rapidly deplete the primer layer of inhibitor resulting in a loss of protection. One of the fortuitous properties of zinc and strontium chromates is the limited solubility of these compounds in water (about 1.2 g/1 at 15°C [33]). 

Water-borne primers may or may not contain chromate-based corrosion inhibitors. The limited solubility of chromate salts in water makes them less than ideal for use in water-based primers, and much work has gone into developing alternatives [36], but the performance of recently developed water based primers using strontium chromate as the corrosion inhibitor is excellent, however, and appears equivalent to the solvent-borne analogues [37]. 

In all cases a priming coat of paint containing some form of hexavalent chromium such as zinc or strontium chromate should be used. 

Self regulating chromium The self-regulating chromium solutions were introduced to eliminate the need for maintaining the correct catalyst concentration by periodic analysis they depend on the addition of a sparingly soluble sulphate to the bath which supplies the correct amount of SO 4 automatically. Initially strontium sulphate (solubility approx. l-75g/l at 30°C and 21 g/1 at 40°C) was employed for this purpose. The strontium sulphate forms a layer on the bottom of the bath, which must be stirred from, time to time. A bath with a CrO, concentration of 250 g/1 would have a catalyst content of l 52g/l SrS04 and 4-35 g/1 of KjSiF. Potassium dichromate and strontium chromate have also found application as additives for the control of the saturation solubility of the catalyst. 

A primer On metal, the purposes of a primer are to enhance corrosion protection and to give excellent adhesion. The primer will contain anticorrosive pigments, such as strontium chromate or zinc phosphate, which will slowly release ions that can repair damage or faults in the underlying conversion coating. 

Precipitation reactions, like all reactions, reach a position of equilibrium. Suppose, for example, solutions of Sr(N03)2 and K2Cr04 are mixed. In this case, Sr2+ ions combine with Cr042- ions to form a yellow precipitate of strontium chromate, SrCr04 (Figure 16.1). Very quickly, an equilibrium is established between the solid and the corresponding ions in solution ... 

In the laboratory, strontium chromate (Ksp = 3.6 X 10-5) can be prepared by mixing solutions containing strontium ions and chromate ions, where the concentrations of these ions are high enough to form a precipitate. Decide whether a precipitate will form when... 

Strontium chromate should, and does, dissolve spontaneously to form a 0.0010 M water solution. As you might expect, its solubility at 25°C lies between 1M and 0.0010 M, at about 0.0060 M. 

Strong electrolyte A compound that is completely ionized to ions in dilute water solution, 37 Strontium, 543 Strontium chromate, 434 Structural formula A formula showing the arrangement of bonded atoms in a molecule, 34,579-580,586,590,593, 597... 

Ammonium chromate Potassium chromate Chromium potassium sulphate Lithium chromate (yitomium trinitrate Sodium chromate Clsomium fV )oxide Lead chromate Strontium chromate 2nc ctvomate... 

Strontium chloride, 23 318, 323 Strontium chromate, 23 323, 6 557t, 558 air standards and classification, 6 549t molecular formula, properties, and uses, 6 562t... 

Some compounds, such as strontium chromate and strontium fluoride, are carcinogens and toxic if ingested. Strontium-90 is particularly dangerous because it is a radioactive bone-seeker that replaces the calcium in bone tissue. Radiation poisoning and death may occur in people exposed to excessive doses of Sr-90. Strontium-90, as well as some other radioisotopes that are produced by explosions of nuclear weapons and then transported atmospherically, may be inhaled by plants and animals many miles from the source of the detonation. This and other factors led to the ban on atmospheric testing of nuclear and thermonuclear weapons. 

The lARC has concluded that there is sufficient evidence in humans for the carcinogenicity of chromium(Vl) compounds as encountered in the chromate production, chromate pigment production, and chromate plating industries. In experimental animals there is sufficient evidence for the carcinogenicity of calcium chromate, zinc chromates, strontium chromate, and lead chromate. ... 

Strong-inorganic-acid mists containing sulfuric acid (see Mists and vapours from sulfuric acid and other strong inorganic acids) Strontium chromate (see Chromium and ehromium compounds) Styrene... 

Strontium chromate [7789-06-2] M 203.6. Crystd from water (40ml/g) by cooling. 

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