Molecular Formula | Cr |
Molar Mass | 52 |
Density | 7.14 g/mL at 25 °C (lit.) |
Melting Point | 1857 °C (lit.) |
Boling Point | 2672 °C (lit.) |
Flash Point | 50°F |
Water Solubility | Insoluble in water. |
Appearance | Ash particles |
Specific Gravity | 7.2 |
Color | Silver-gray |
Odor | Odorless |
Exposure Limit | 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 solubleand certain water insoluble, 0.05 mg/m3(ACGIH). |
Merck | 13,2252 |
PH | <1 (H2O, 20°C) |
Storage Condition | no restrictions. |
Stability | Stable. Incompatible with carbonates, strong bases, mineral acids, lithium, sulfur dioxide, strong acids. |
MDL | MFCD00010944 |
Physical and Chemical Properties | Silver-white metal (body-centered cubic system) with slightly darker gray. melting point (1857±20)℃ boiling point 2672 ℃ relative density 7.20 ℃ solubility: soluble in dilute sulfuric acid, hydrochloric acid, insoluble in water, nitric acid, aqua regia. |
Use | Used for refining high temperature alloys, resistance alloys, precision alloys |
Risk Codes | R11 - Highly Flammable R20/21/22 - Harmful by inhalation, in contact with skin and if swallowed. R34 - Causes burns R40 - Limited evidence of a carcinogenic effect R23 - Toxic by inhalation R67 - Vapors may cause drowsiness and dizziness R36 - Irritating to the eyes |
Safety Description | S16 - Keep away from sources of ignition. S26 - In case of contact with eyes, rinse immediately with plenty of water and seek medical advice. S36/37/39 - Wear suitable protective clothing, gloves and eye/face protection. S45 - In case of accident or if you feel unwell, seek medical advice immediately (show the label whenever possible.) S36/37 - Wear suitable protective clothing and gloves. S27 - Take off immediately all contaminated clothing. |
UN IDs | UN 2924 3/PG 2 |
WGK Germany | 3 |
RTECS | GB4200000 |
TSCA | Yes |
HS Code | 8112 21 90 |
Hazard Class | 4.1 |
Packing Group | 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. |
Reference Show more | Jun Jun, Shen Yimao, Qiu Tongji, et al. Study on secondary utilization of filter residue of Chrome Leather chip hydrolysis [J]. Leather chemical industry, 2019, 36(01):20-24. |
is a slightly darker gray silver metal (body-centered cubic system). Melting point (1857±20) °c. Boiling point 2672 °c. Relative density d28 7.20. Soluble in dilute sulfuric acid, dilute hydrochloric acid, insoluble in water, nitric acid, aqua regia.
The production of chromium metal, more than the use of chromite calcium roasting process, the two chromium oxide into sodium chromate, with dilute solution and water immersion into sodium chromate solution, and then produced by electrolytic method.
used for refining high temperature alloy, resistance alloy, precision alloy as chromium additive. Pure chromium is used for electroplating.
metal chromium powder can burn when exposed to high temperature and open flame. Almost no harmful effects on the human body, no report of industrial poisoning. But Hexavalent chromium ions are carcinogenic. Packaging and storage of the products shall be carried out in an iron drum lined with polyethylene plastic bags, with a net weight of 50kg or log/kg per barrel. Should be stored in a dry, clean warehouse. Not co-stored with acids. Dry powder and sand can be used to put out the fire.
resistivity | 12.7 ***-CM, 20°C |
NIST chemical information | information provided by: webbook.nist.gov (external link) |
(IARC) carcinogen classification | 3 (Vol. Sup 7, 49) 1990 |
EPA chemical substance information | information provided by: ofmpeb.epa.gov (external link) |
physical properties | chromium is a silvery white, lustrous metal, pure chromium is ductile, and chromium containing impurities is hard and brittle. Density 7.20g/cm3. Soluble in strong alkaline solution. Chromium has a high corrosion resistance, in the air, even in the red hot state, oxidation is very slow. Insoluble in water. Plating on the metal can play a protective role. |
Use | due to the brittleness of chromium alloys, the use as metal materials is still under study, and chromium is mainly used in iron alloys (such as chromium iron). Form for the production of stainless steel and various alloy steels. Chromium is used as an additive for aluminum alloys, cobalt alloys, titanium alloys, high temperature alloys, resistance Fever alloys, and the like. Chromium oxide is used as a light-resistant and heat-resistant coating, and can also be used as a colorant for abrasives, glass and ceramics, and a catalyst for chemical synthesis. Basic chromium sulfate (trivalent chromium salt) is used as tanning agent for leather. Chrome alum and dichromate are used as mordant, impregnating agent and various pigments for fabric dyeing. Chrome and chromizing can make steel and copper, aluminum and other metals to form a corrosion resistant surface, and bright and beautiful, a large number of used in furniture, automotive, construction and other industries. In addition, chromium ore is also used in a large number of refractory materials. used for refining high-temperature alloys, resistance alloys, precision alloys, etc. used in the manufacture of chromium-nickel steel and electronic, Instrument Industry used for refining high-temperature alloys, resistance alloys, precision alloys are used as chromium additives. chrome plating; Manufacturing chromium steel and chromium-nickel steel alloy used in the manufacture of tough and high-quality steel and stainless steel, acid-resistant alloy; Pure chromium for electroplating. |
medical function | control of blood glucose level chromium is essential for blood glucose metabolism, it can improve insulin action, the smooth entry of glucose into the body's cells for metabolism to produce energy, if you have diabetes or hypoglycemia, you can use chromium to regulate glucose metabolism in the body. cardiovascular protection chromium also plays an active role in increasing high-density lipoprotein (HDL), the beneficial lipoprotein for the human body, and reducing the level of peribiliary alcohol, contribute to the prevention and improvement of atherosclerosis, prevention of hypertension and other cardiovascular diseases. weight control chromium can help people reduce their craving for sweets, help reduce body fat content, increase lean muscle tissue, this helps to promote metabolism and maintain ideal body weight (the more lean muscle tissue, the higher the metabolic rate), which is very popular in weight loss food. |
harm to human body | chromium compounds do not damage intact skin, however, when the skin is scuffed and exposed to chromium compounds, the harmful effect can occur. The Incidence Rate chance of chromium-induced skin ulcer is high, mainly related to the length of exposure, skin allergy and personal hygiene habits. Chromium ulcers mainly occur in the hands, arms and feet, but as long as the skin is damaged, regardless of any part, can occur. The root of the nail is exposed, easy to accumulate dirt, the skin is also the most vulnerable to damage, so these parts are also easy to form chromium sores. Before the formation of chromium sores, the skin initially appear red and swollen, with itching, do not make appropriate treatment can invade the deep. The ulcer was covered with a hard scab of secretion, with protuberance in the surrounding part, deep in the center and filled with putrid meat, with prominent margin, gray-red in color, with local pain. The ulcer was inverted conical, with small ulcer surface, generally not more than 3mm, sometimes can be as large as 12-30mm, or as small as the size of the needle tip, if the treatment is ignored, further development can be deep to the bone, severe pain, slow healing. |
application range | raw materials for various foods, health foods and medicines fortified foods, such as dairy products, biscuits, beverages, fruit juices, flour, raw materials for nutritional fortification of chromium in infant formula |
production method | for the production of chromium metal, the calcium roasting process of chromite has been used to convert chromium oxide into sodium chromate, A sodium chromate solution was prepared by immersion in dilute solution and water and then produced by electrolysis. Due to the high content of impurities such as silicon and aluminum in the chromite and its additives, the amount of slag discharged in the process is large, and the environment is seriously polluted because the slag contains toxic water soluble cr6. In recent years, it is proposed that Chromite is firstly reduced into carbon ferrochrome, and then oxidized and roasted with soda ash to obtain sodium chromate solution. The advantage of this method is that most of the impurities in chromite enter the smelting slag, the total chromium in the mixture can be higher, and the soda ash consumed in the roasting process is less. When sodium chromate is used as compensation liquid for electrolysis, the cathode liquid is 40g/L (Cr), 90g/L (NH4); the anode liquid was 22g/L (Cr),18g/L (NH4),200g/L H2S04. Stainless steel for cathode, anode: Pb-Ag alloy at A temperature of about 60 ° C., cell voltage of 4.8V, current density of 8.6 A/cm<2>. Then, electrolysis was carried out to obtain a finished metallic chromium product. |
category | toxic substances |
toxicity grade | high toxicity |
Acute toxicity | not reported-rat LD50: 27.5 mg/kg |
flammability hazard characteristics | non-combustible; Toxic Chrome-containing fumes generated in the fire scene; |
storage and transportation characteristics | The warehouse is low temperature, ventilated and dry, and stored separately from food raw materials; avoid dust |
fire extinguishing agent | water, carbon dioxide, dry powder, foam |
Occupational Standard | TWA 0.5 mg (chromium)/m3 |
spontaneous combustion temperature | 580°C |
toxic substance data | information provided by: pubchem.ncbi.nlm.nih.gov (external link) |
immediate life-threatening and health concentration | 250 mg Cr/m3 |