Chromium salts aquated

An example of some of the newer regulations is the restriction against the use of the popular mud dispersant, chrome lignosulfonate. It is expected that this regulation is merely the initial step toward ruling out the use of all heavy metal salts commonly employed in the formulation of well fluids because of their toxicity to aquatic life and humans. This means that the use of zinc and lead, in addition to chromium, may not be allowed in the future. At least one major oil company has already taken steps in this direction by ruling out the use of heavy metal salts in any well fluid in their worldwide operations. 

Zinc salts rapidly generate zinc hydroxide or salt protective films on cathodic surfaces when they are added to cooling water. They are generally used in conjunction with other corrosion inhibitors, such as organophosphates. BETZ manufacturers a combination HEDP-zinc inhibitor. They have also been used with chromate systems to inhibit the chromate concentrations required. A disadvantage of zinc is its tendency to precipitate in pH environments greater than 8.0 (Roti 1985). While the toxicity of zinc to humans is far lower than that of chromium, its toxicity to marine and aquatic life is high. 

All phases of coordination chemistry are encompassed by the complex chromium(III) azides. A yellow, crystalline salt of the composition [Cr (NH3)6] (N3)3, for example, is not a true azido complex but the azide salt of the hexammmechromium(III) cation. It is soluble in water the heated solution aquates over a red intermediate, aquopentamminechromium, to chromium hydroxide. The dry salt explodes in the match test. Similarly explosive is the neutral complex triamminetriazidochromium(III), [(NH3)3Cr (N3)3]°, an olive-green, crystalline solid which is, expectedly, insoluble in water and organic solvents it explodes thermally within 25 sec at 250°, and within 1 sec at 300°C, and also on impact [145]. The compound was made by heating a solution of 10 g hexamminechromium perchlorate, 10 g ammonium sulfate, and 50 g sodium azide in 300 ml water for 90 min. 

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