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Topic: Chromium trioxide

	Chromium - LoveToKnow 1911
		Chromium as prepared by the Goldschmidt process is in a passive condition as regards dilute sulphuric acid and dilute hydrochloric acid at ordinary temperatures; but by heating the metal with the acid it passes into the active condition, the same effect being produced by heating the inactive form with a solution.
		Chromium in the form of its salts may be estimated quantitatively by precipitation from boiling solutions with a slight excess of ammonia, and boiling until the free ammonia is nearly all expelled.
		Chromium trioxide, Cr03, is obtained by adding concentrated sulphuric acid to a cold saturated solution of potassium bichromate, when it separates in long red needles; the mother liquor is drained off and the crystals are washed with concentrated nitric acid, the excess of which is removed by means of a current of dry air.
	www.1911encyclopedia.org /Chromium (2786 words)

	Chromic acid - Wikipedia, the free encyclopedia
		Although chromium can exist in a number of oxidation states, hexavalent chromium is commonly reduced in redox reactions to a +3 oxidation state, where the Cr ion is a distinctively different blue green color.
		In organic chemistry, more dilute hexavalent chromium solutions can be used to oxidize a hydroxyl group and the carbon atom it is bonded to in a primary or secondary alcohol to a carbonyl group.
		Chromium trioxide and pyridinium hydrochloride (pyridine neutralized by HCl) can be used to form a pyridinium chlorochromate reagent under anhydrous conditions.
	en.wikipedia.org /wiki/Chromium_trioxide (579 words)

	Encyclopedia :: encyclopedia : Chromium (Site not responding. Last check: 2007-10-25)
		Chromium is a chemical element in the periodic table that has the symbol Cr and atomic number 24.
		Chromium salts are used in the tanning of leather.
		During the 1800s chromium was primarily used as a component of paints but now the primary use (85%) is for metal alloys, with the remainder used in the chemical industry and refractory and foundry industries.
	www.hallencyclopedia.com /Chromium (975 words)

	Chromium - Wikipedia, the free encyclopedia
		During the 1800s chromium was primarily used as a component of paints and in tanning salts but now the primary use in is for metal alloys and is responsible for 85% of the use of chromium.
		Chromium is obtained commercially by heating the ore in the presence of aluminium or silicon.
		As chromium compounds were used in dyes and paints and the tanning of leather, these compounds are often found in soil and groundwater at abandoned industrial site, now needing environmental cleanup and remediation per the treatment of brownfield land.
	en.wikipedia.org /wiki/Chromium (1192 words)

	HHMI Lab Safety: LCSS: CHROMIUM TRIOXIDE AND OTHER CHROMIUM(VI) SALTS (Site not responding. Last check: 2007-10-25)
		Chromium trioxide and other chromium(VI) salts are moderately toxic substances by ingestion; 1 to 15 g may be a fatal dose in humans.
		Chromium trioxide and certain other chromium(VI) compounds are useful as strong oxidizing agents in the laboratory, but appropriate precautionary measures should be taken when conducting these reactions.
		Chromium trioxide has been reported to react violently with a variety of substances, including readily oxidized organic compounds such as acetone, acetaldehyde, methanol, ethanol, diethyl ether, ethyl acetate, acetic acid, and DMF, and violent reactions may also occur on reaction with alkali metals, gaseous ammonia, phosphorus, and selenium.
	www.hhmi.org /about/labsafe/lcss/lcss25.html (765 words)

	Chromium (Site not responding. Last check: 2007-10-25)
		Chromium trioxide is used for metal plating and treatment, wood treatment and preservative, and in the manufacture of chromated copper arsentate.
		Chromium phosphate is slightly soluble in cold water, soluble in acids and alkalies, and insoluble in acetic acid.
		Hexavalent chromium compounds are corrosive and cause chronic ulceration and perforation of the nasal septum.
	www.nsc.org /ehc/chemical/chromium.htm (1646 words)

	Known Carcinogen: Chromium and Certain Chromium Compounds (Site not responding. Last check: 2007-10-25)
		Chromium is used as an alloying and plating element on metal and plastic substrates for corrosion resistance in chromium- containing and stainless steels and in protective coatings for automotive and equipment accessories.
		In 1985, 39% of the chromium trioxide produced was used for metal plating and treatment, 44% was used in wood treatment and preservatives, and 11% was exported (Chem.
		Chromium trioxide is used in chromium plating and in the manufacture of chromated copper arsenate (NCI DCE, 1985c).
	www.p2pays.org /ref/03/02845.htm (2355 words)

	Ceramics Today - Chrome
		Chromium in its 2+ state frequently oxidizes rapidly to 3+ form, and the 4+ and 5+ states are found only as intermediates in the conversion between 3+ and 6+ states.
		Chromium is essentially excreted in the urine and in professionally exposed personnel, its urinary concentration reflects mostly the amount of recently absorbed soluble hexavalent chromium.
		Studies show that the predominant form of chromium recovered in blood and tissues, even after exposure to hexavalent chromium, is trivalent chromium because the hexavalent form is reduced to the trivalent form in tissues in biological media. Reduction of Cr6+ to Cr3+ decreases the entry of chromium into cells and lessens intracellular and DNA damage.
	www.ceramicstoday.com /articles/chrome_english.htm (3748 words)

	Chromium (Cr) - Chemical properties, Health and Environmental effects
		Chromium main uses are in alloys such as stainless steel, in chrome plating and in metal ceramics.
		Chromium is used in metallurgy to impart corrosion resistance and a shiny finish; as dyes and paints, its salts colour glass an emerald green and it is used to produce synthetic rubies; as a catalyst in dyeing and in the tanning of leather; to make molds for the firing of bricks.
		Chromium is not known to accumulate in the bodies of fish, but high concentrations of chromium, due to the disposal of metal products in surface waters, can damage the gills of fish that swim near the point of disposal.
	www.lenntech.com /Periodic-chart-elements/Cr-en.htm (964 words)

	EPA - Air Toxics Website - Chromium Compounds
		Chromium compounds, in either the chromium (III) or chromium (VI) forms, are used for chrome plating, the manufacture of dyes and pigments, leather and wood preservation, and treatment of cooling tower water.
		Chromium occurs in the environment predominantly in one of two valence states: trivalent chromium (Cr III), which occurs naturally and is an essential nutrient, and hexavalent chromium (Cr VI), which, along with the less common metallic chromium (Cr 0), is most commonly produced by industrial processes.
		Chromium compounds are stable in the trivalent state, with the hexavalent form being the second most stable state.
	www.epa.gov /ttn/atw/hlthef/chromium.html (2214 words)

	[No title]
		Skin Irritation/Corrosivity Aqueous chromium trioxide, which is also known as chromic acid, is a corrosive substance due to its low pH (the pH of a 1% solution is less than 1).
		The reports of asthma are in electroplaters, who may be exposed to a mist of dissolved chromium trioxide (i.e.chromic acid) from the plating bath, and there are two studies in which it is known that chromium trioxide was present in the atmosphere and associated with asthma.
		The speed with which this man mounted an allergic response to the accidentally discharged chromium trioxide (within 12 hours of exposure) strongly indicates that he was already immunologically sensitised to hexavalent chromium but until this period of prolonged/high exposure, he had not shown clinical symptoms.
	ecb.jrc.it /classlab/9001a4_UK_hse_Chromium_trioxide.doc (1631 words)

	Toxicological Profile for Chromium - Agenct for Toxic Substances
		chromium in the environment occurs as particle-bound chromium or chromium dissolved in droplets.
		as a 3:2 mixture of chromium(VI) trioxide and chromium(III) oxide, or to 15.5 mg
		as a 3:2 mixture of chromium(VI) trioxide and chromium(III) oxide for
	www.weitzlux.com /chromiumtoxicological_1926.html (10564 words)

	Chromium six
		Chromium can be inhaled when chromium dust, mist, or fumes are in the air.
		Chromium fume is created by welding or cutting on stainless steel or metals that are coated with a chromium material.
		The chromium coating must be stripped for at least four inches from the area of heat application before welding or cutting.
	www.dhs.ca.gov /ohb/HESIS/cr6.htm (2259 words)

	[No title]
		Symptoms of respiratory tract irritation are known to occur among chrome plating workers exposed to a mist of aqueous chromium (VI) trioxide.
		In mice exposed to 1.8 x 10-3 mg/l chromium trioxide for 2 hours/day or 3.6 x 10-3 mg/l for 30 minutes/day, twice a week for up to 12 months, hyperplasia of the tracheal and bronchial epithelia, inflammation and metaplasia of the lower respiratory tract and emphysema were reported.
		Introduction Inorganic chromium exists as the elemental metal and in a range of oxidation states, for which information is primarily available on 3, Cr (III) and 6, Cr (VI).
	ecb.jrc.it /classlab/9001a2_UK_crtrioxide.doc (2559 words)

	Chromium (IARC Summary & Evaluation, Volume 49, 1990)
		Chromium trioxide (chromic acid) has been tested as a mist by inhalation at two dose levels in mice and as a solid by intrabronchial implantation in three studies in rats.
		Inhaled chromium[VI] from welding and chrome-plating aerosols is readily absorbed from the respiratory tract.
		Chromium trioxide increased fetal death rate, caused growth retardation and increased the frequency of skeletal deformities and of cleft palate in rodents.
	www.inchem.org /documents/iarc/vol49/chromium.html (2217 words)

	ATSDR - Public Health Statement: Chromium
		Chromium is a naturally occurring element found in rocks, animals, plants, soil, and in volcanic dust and gases.
		Chromium compounds, mostly in chromium(III) or chromium(VI) forms, produced by the chemical industry are used for chrome plating, the manufacture of dyes and pigments, leather tanning, and wood preserving.
		Therefore, pregnant women who were exposed to chromium in the workplace or by living near chromium waste sites may transfer chromium from their blood into the baby where it may build up at levels greater than in the mother.
	www.atsdr.cdc.gov /toxprofiles/phs7.html (3661 words)

	Life Extension Magazine February 1996
		Chromium is an unacceptable ingredient in children's vitamin-mineral supplements.
		Acceptable sources: Brewers or chromium yeast, trivalent mineral salts, chromic chloride, chromic sulphate, and chromic oxide but not chromic trioxide or chromium HVP 'chelate.
		Chromium Is one of the safest of nutrients.
	www.lef.org /magazine/mag96/feb96-FDA4.html (1048 words)

	Chemical Hazard Scores
		The score of 22 for chromium is for chromium metal and Cr III compounds.
		Water-soluble compounds: chromium trioxide (chromic acid), and monochromates and dichromates of sodium, potassium, ammonium, lithium, cesium and rubidium;
		Water-insoluble compounds: zinc chromate, strontium chromate and sintered chromium trioxide; [ACGIH]
	www.haz-map.com /hazscore.htm (411 words)

	Chromium poisoning and your health
		Long-term exposure to chromium has been associated with lung cancer in workers exposed to levels in air that were 100 to 1,000 times higher than those found in the natural environment.
		We have no reliable information that any form of chromium has harmful effects on reproduction or causes birth defects in humans, though it does not seem likely that the amount of chromium that most people are exposed to will result in reproductive or developmental effects.
		In animals that breathed high levels of chromium, harmful effects on the respiratory system and a lower ability to fight disease were noted.
	www.weitzlux.com /exposedchromiumpoisoning_712.html (1199 words)

	DRDB: SDAPCD 1201 HEXVALNT CHROM-CHROME PLTNG & CHROM ACID ANODIZING (Site not responding. Last check: 2007-10-25)
		The provisions of Sections (d) and (e) of this rule shall not apply to non-immersion plating or anodizing operations in which the plating or anodizing solution is applied to the part being plated or anodized by use of a brush or stylus for the purposes of touch-up or repair.
		If uncontrolled chromium emissions from the hard chrome plating or chromic acid anodizing stationary source are greater than or equal to 10 pounds per year, the stationary source shall also comply with the requirements of Subsections (d)(2)(ii)(C) and (e)(4)(iii).
		Measurements of chromium emissions subject to Subsection (d)(2) of this rule shall be conducted in accordance with ARB Method 425 as it exists on May 28, 1991.
	www.arb.ca.gov /drdb/sd/suphtml/r1201.htm (1527 words)

	DRDB: SACAQMD 480 CHROME PLATING AND CHROMIC ACID ANODIZING (Site not responding. Last check: 2007-10-25)
		The chromium emissions from the emissions collection systems serving the plating tank are reduced by at least 95% from the uncontrolled chromium emissions, or; b.
		The chromium emissions from the emissions collection systems serving the plating tank are reduced to less than 0.15 milligrams(mg) of chromium per ampere-hour of electrical charge applied to the plating tank.
		The chromium emissions from the emissions collection systems serving the plating tank are reduced to less than 0.03 mg of chromium per ampere-hour of electrical charge applied to the plating tank.
	www.arb.ca.gov /drdb/sac/suphtml/r480.htm (1248 words)

	Chemical Safety Data: Chromium trioxide
		* Chromium trioxide** is a dangerous material in both the chemical and health hazards that it poses - it must be handled with caution.
		Like most chromium (VI) compounds it is probably carcinogenic.
		Use a fume cupboard, but do not regard this as a means of ensuring complete safety; if you create significant amounts of chromium trioxide dust within the fume cupboard it may be swept up by the air flow through the hood and desposited arcross the outside environment.
	physchem.ox.ac.uk /~hmc/hsci/chemicals/chromium_trioxide.html (195 words)

	Chromium HQ : Periodic Table Chromium
		Chromium [Cr] [24] - Chemical element datasheet - Periodic Table...
		Whilst every care is taken in the maintenance of this site, Chromium HQ does not warrant or guarantee the accuracy or completeness of the content available on this Website.
		Chromium HQ excludes all liability of any kind (including negligence) in respect of any third party information or other material made available on, or which can be accessed using, this Website.
	chromiumhq.com /periodictablechromium/index.php (689 words)

	Articles - Chromium (Site not responding. Last check: 2007-10-25)
		Chromium** is what makes a ruby red, and therefore is used in producing synthetic rubies.
		* Chromium salts are used in the tanning of leather.
		Writing in ´´Science´´, Tailuan Nguyen and coworkers of the University of California describe how they synthesized a compound, which does not appear to have a common name, of chromium and a hydrocarbon radical; X-ray diffraction showed unambiguously that the compound had a quintuple bond joining the two central chromium atoms.
	www.zdiamond.net /articles/Chromium (1143 words)

	Sentury Reagents, Inc. Chromium Trioxide MSDS
		Then treat the spill area with a reducing agent to convert the Hexavalent Chromium to the Trivalent form and neutralize with a weak base.
		WASTE DISPOSAL METHOD: Hexavalent Chromium in solution may be reduced to Trivalent Chromium by reducing agents, such as Sodium Bisulfate, Sulfur Dioxide, Ferrous Sulfate or Ferrous Chloride.
		The reduced Chromium may be precipitated as the Chromic Oxide by neutralizing to a pH 7.5 with Soda Ash, Caustic Soda or Lime.
	www.senturyreagents.com /chromium_trioxide_msds.htm (1197 words)

	Safety and Health Topics: Hexavalent Chromium - Hazard Recognition
		Calcium chromate, chromium trioxide, lead chromate, strontium chromate, and zinc chromate are known human carcinogens.
		Hexavalent chromium is considered a potential lung carcinogen.
		Characterizes the toxicological and adverse health effects information regarding chromium and chromium compounds.
	www.osha.gov /SLTC/hexavalentchromium/recognition.html (625 words)

	Haz-Map: Occupational Exposure to Hazardous Agents
		Chromium metal and Cr III compounds are IARC 3 (not classifiable), while the Cr VI compounds are IARC 1 (human carcinogens); Hexavalent chromium compounds (Cr VI) include: A) water-soluble compounds: chromium trioxide (chromic acid), and monochromates and dichromates of sodium, potassium, ammonium, lithium, cesium and rubidium;
		For chromium (VI), water-soluble fume: Total Cr in urine = 10 ug/L (increase during shift) or 25 ug/L (end of shift at end of workweek);
		The available toxicological data show no evidence that an acute exposure to a high concentration of chromium metal would impede escape or cause any irreversible health effects within 30 minutes.
	hazmap.nlm.nih.gov /cgi-bin/hazmap_generic?tbl=TblAgents&id=7 (342 words)

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