Chromic acid and chromates

Workplace. The Occupational Safety and Health Administration (OHSA) has estabUshed workplace permissible exposure limits (PEL) for chromium metal and three forms of chromium compounds. OSHA s PEL for chromic acid and chromates is 0.1 mg/m 3 both a ceiling, ie, no exposure above this concentration is allowed, and an 8-h time-weighted average (TWA). Chromium metal and insoluble chromium salts have an 8-h TWA PEL of 1.0 mg/m Cr, and the same standard is 0.5 mg/m Cr for soluble Cr(III) and Cr(II) compounds (144). 

Chloro 6-trichloromethyl pyridine (N-Serve ) Chromates, certain insoluble forms Chromic acid and chromates (as Cr)... 

OSHA 8-Hour time weighted average Chromium(ll) Chromium(lll) Chromium metal and insoluble salts Chromic acid and chromates 0.5 mg/m3 0.5 mg/m3 1.0 mg/m3 1.0 mgCrO3/10m3 29 CFR 1910.1000 OSHA 1999a... 

Chromium. Chromium is not an easily analyzed element because three distinct standards are listed by OSHA (Tables IV and V ). One standard exists for hexavalent chromium, chromic acid and chromates, another standard for soluble chromium compounds and chromous salts, and another standard for insoluble chromium compounds and chromium metal. The permissible amount of chromium in air decreases as the oxidation state increases. The analysis of chromium is further complicated by the multiplicity of NIOSH methods for chromium compounds. Hexavalent chromium shall be collected on PVC filters, although a criteria document for chromic acid (14) specifies mixed cellulose ester filters. The analytical method described in the hexavalent... 

CHROMIC ACID AND CHROMATES (as Cr03)(Chromates (i.e., chromium (VI) compounds) have variable molecular formulas and variable formula weights. The molecular formula for chromic acid is CrOa. The formula weight of chromic acid is 100.0)... 

DISPOSAL AND STORAGE METHODS chromic acid and chromates may be disposed of in sealed containers in a secured, sanitary landfill store in a cool, dry location maintain adequate ventilation separate form combustible materials, halogens, sulfides, and metals. 

Chromic acid and chromates 1 Formula CrOs (acid) CAS 1333-82-0 (CrOs) RTECS GB6650000 (CrOj) IDLH Ca [15 mg/m I asCr(VI) ]... 

Chromic Acid and Chromates (as CrOs), Chromium(ii) and Chromium(lll) Compounds (as Cr), and Chromium Metai (as Cr)... 

The OSHA PEL is 0.005 mg CrOs/m (8-hour TWA) for chromic acid and chromates (ineluding tert-butyl ehromate with a skin designation and zinc chromate) 0.5 mg Cr/m (8-hour TWA) for chromium(II) and chromium(III) compounds and 1 mg Cr/m (8-hour TWA) for chromium metal and insoluble salts. 

Strong oxidizers, such as chlorates, chlorites, perchlorates, perclorites, permanganates, persulfates, chromic acid and chromates, nitrates, fuming nitric acid, peroxides, and chlorine... 

The oxidation of naphthalene was carried out with chromic acid and chromates, regenerated by electrochemical reoxidation. This method was first used by the Farbwerke Hoechst. In 1891, it was accidentally discovered at BASF haX naphthalene could be oxidized by concentrated sulfuric add in the presence of mercury. In 1897, introduced the first synthetic indigo to the market, followed shortly thereafter by Farbwerke Hoechst, Synthetic indigo rapidly replaced the natural product in the market in spite of harsh competition of the producers of natural indigo, especially of the Provence/France. 

The level of concern for health hazards frequently depends on the chemical form of the metal compounds. This is primarily because the critical influence of chemical form on the uptake of inhaled, ingested, or skin-deposited materials, and can result in substantially different exposure limits for different compounds. For example, the ACGIH TWA TLV for exposure to chromium compounds is most restrictive for insoluble hexavalent chromium compounds (0.01 mg/m ), which are poorly removed from lung following inhalation less restrictive for water-soluble hexavalent compounds (0.05 mg/m ), which are more readily absorbed into the bloodstream following inhalation and least restrictive for the less-reactive trivalent chromium compounds and chromium metal (0.5 mg/m ) (11). Chromic acid and chromate aerosols can be caustic to mucous membranes, and some water-insoluble chrome IV compounds are carcinogens. In addition,... 

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