Chromium , 99.5%metalsbasis, ≥325 , 7440-47-3

CAS NO.：7440-47-3

Empirical Formula: Cr

Molecular Weight: 52

MDL number: MFCD00010944

EINECS: 231-157-5

PRODUCT Properties

• Melting point: 1857 °C (lit.)
• Boiling point: 2672 °C (lit.)
• Density: 7.14 g/mL at 25 °C (lit.)
• Flash point: 50 °F
• storage temp.: no restrictions.
• solubility: reacts with dilute acid solutions
• form: powder
• color: Silver-gray
• Specific Gravity: 7.2
• PH: <1 (H2O, 20°C)
• Odor: Odorless
• Resistivity: 12.7 μΩ-cm, 20°C
• Water Solubility: Insoluble in water.
• Merck: 13,2252
• Exposure limits: TLV-TWA: chromium metal 0.5 mg/m³ (ACGIH and MSHA), 1 mg/m³ (OSHA); Cr(II) and Cr(III) compounds 0.5 mg/m³ (ACGIH); Cr(VI) compounds, water soluble and certain water insoluble, 0.05 mg/m³ (ACGIH).
• Stability: Stable. Incompatible with carbonates, strong bases, mineral acids, lithium, sulfur dioxide, strong acids.

Description and Uses

Chromium as a metallic element was first discovered over 200 years ago, in 1797. But the history of chromium really began several decades before this. In 1761, in the Beresof Mines of the Ural Mountains, Johann Gottlob Lehmann obtained samples of an orange-red mineral, which he called ‘Siberian red lead.’ He analyzed this mineral in 1766 and discovered that it contained lead “mineralized with a selenitic spar and iron particles.” The mineral he found was crocoite, a lead chromate (PbCrO4).

The best-known use of chromium is for the plating of metal and plastic parts to producea shiny, reflective finish on automobile trim, household appliances, and other items where abright finish is considered attractive. It also protects iron and steel from corrosion.It is used to make alloys, especially stainless steel for cookware, and items for whichstrength and protection from rusting and high heat are important.Its compounds are used for high-temperature electrical equipment, for tanning leather, asa mordant (fixes the dyes in textiles so that they will not run), and as an antichalking agentfor paints.Some research has shown that, even though most chromium compounds are toxic, a smalltrace of chromium is important for a healthy diet for humans. A deficiency produces diabeteslike symptoms, which can be treated with a diet of whole-grain cereal, liver, and brewer’s yeast.Chromium’s most important radioisotope is chromium-51, which has a half-life of about27 days. It is used as a radioisotope tracer to check the rate of blood flowing in constrictedarteries.Some chromium compounds (e.g., chromium chloride, chromic hydroxide, chromic phosphate) are used as catalysts for organic chemical reactions.In 1960 the first ruby laser was made from a ruby crystal of aluminum oxide (Al₂O₃). Thesecrystals contain only a small amount of chromium, which stores the energy and is responsiblefor the laser action. A small amount of chromium found in the mineral corundum is responsible for the bright red color of the ruby gemstone.

Safety

• Symbol(GHS): GHS02,GHS08,GHS09
• Signal word: Warning
• Hazard statements: H410-H351-H228
• Precautionary statements: P201-P202-P280-P308+P313-P405-P501a-P210-P240
• Hazard Codes: F,C,Xn,Xi
• Risk Statements: 11-20/21/22-34-40-23-67-36
• Safety Statements: 16-26-36/37/39-45-36/37-27
• RIDADR: UN 2924 3/PG 2
• OEB: C
• OEL: TWA: 0.5 mg/m3
• WGK Germany: 3
• RTECS: GB4200000
• Autoignition Temperature: 580°C
• TSCA: Yes
• HS Code: 8112 21 90
• HazardClass: 4.1
• PackingGroup: III
• Toxicity: Elemental chromium and certain chromium compounds have been designated as carcinogens, hazardous substances, hazardous waste constituents, and priority toxic pollutants. Some of those compounds designated as hazardous are chromic acetate, chromic acid, chromic sulfate, and chromous chloride. Although chromium in the 6+ state is regarded as being the most carcinogenic, there are 6+ compounds that appear to be non-carcinogenic. In addition to their possible carcinogenicity, chromium compounds may have local allergic effects leading to dermatitis. Systemically, 6+ chromium compounds are irritants to the respiratory system and may give rise to pulmonary edema.
• IDLA: 250 mg Cr/m3