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크롬

크롬
크롬 구조식 이미지
카스 번호:
7440-47-3
한글명:
크롬
동의어(한글):
크로뮴(크롬);크롬;크롬분;크롬원소;크롬금속;크롬분말;크롬;크로믹애씨드및그염류
상품명:
Chromium
동의어(영문):
chrom;chrome;CR000060;CR004850;CR000170;CR000130;CR008010;CR000020;CR004200;CR000050
CBNumber:
CB7854190
분자식:
Cr
포뮬러 무게:
52
MOL 파일:
7440-47-3.mol

크롬 속성

녹는점
4 °C
끓는 점
82 °C
밀도
7.14 g/mL at 25 °C(lit.)
인화점
50 °F
저장 조건
Storage temperature: no restrictions.
물리적 상태
powder
색상
Silver-gray
Specific Gravity
7.2
수소이온지수(pH)
<1 (H2O, 20°C)
비저항
12.7 μΩ-cm, 20°C
수용성
Insoluble in water.
Merck
13,2252
노출 한도
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).
안정성
Stable. Incompatible with carbonates, strong bases, mineral acids, lithium, sulfur dioxide, strong acids.
CAS 데이터베이스
7440-47-3(CAS DataBase Reference)
NIST
Chromium(7440-47-3)
EPA
Chromium(7440-47-3)
안전
  • 위험 및 안전 성명
  • 위험 및 사전주의 사항 (GHS)
위험품 표기 F,C,Xn,Xi
위험 카페고리 넘버 11-20/21/22-34-40-23-67-36
안전지침서 16-26-36/37/39-45-36/37-27
유엔번호(UN No.) UN 2924 3/PG 2
WGK 독일 3
RTECS 번호 GB4200000
TSCA Yes
HS 번호 8112 21 90
위험 등급 4.1
포장분류 III
유해 물질 데이터 7440-47-3(Hazardous Substances Data)
그림문자(GHS):
신호 어: Warning
유해·위험 문구:
암호 유해·위험 문구 위험 등급 범주 신호 어 그림 문자 P- 코드
H228 인화성 고체 인화성 고체 구분 1
구분 2
위험
경고
P210, P240,P241, P280, P370+P378
H351 암을 일으킬 것으로 의심됨 (노출되어도 암을 일으키지 않는다는 결정적인 증거가 있는 노출경로가 있다면 노출경로 기재) 발암성 물질 구분 2 경고 P201, P202, P281, P308+P313, P405,P501
H410 장기적 영향에 의해 수생생물에 매우 유독함 수생 환경유해성 물질 - 만성 구분 1 경고 P273, P391, P501
예방조치문구:
P201 사용 전 취급 설명서를 확보하시오.
P202 모든 안전 조치 문구를 읽고 이해하기 전에는 취급하지 마시오.
P210 열·스파크·화염·고열로부터 멀리하시오 - 금연 하시오.
P240 용기와 수용설비를 접지 및 접합시키시오.
P280 보호장갑/보호의/보안경/안면보호구를 착용하시오.
P308+P313 노출 또는 접촉이 우려되면 의학적인 조치· 조언를 구하시오.
P405 밀봉하여 저장하시오.

크롬 C화학적 특성, 용도, 생산

화학적 성질

very hard silvery grey metal

화학적 성질

Chromium may exist in one of three valence states in compounds, , , and . The most stable oxidation state is trivalent chromium; Hexavalent chromium is a less stable state. Chromium (element) blue-white to steel-gray, lustrous, brittle, hard, odorless solid. Elemental:

물리적 성질

Chromium is a silvery white/gray, hard, brittle noncorrosive metal that has chemical andphysical properties similar to the two preceding elements in period 4 (V and Ti). As one of thetransition elements, its uses its M shell rather than its outer N shell for valence electrons whencombining with other elements. Its melting point is 1,857°C, its boiling point is 2,672°C,and its density is 7.19 g/cm3.

Isotopes

There are 26 isotopes of the element chromium; four are stable and foundin nature, and the rest are artificially produced with half-lives from a few microsecondsto a few days. The four stable isotopes and their percentage of contribution to thetotal amount of chromium on Earth are as follows: 50Cr = 4.345%, 52Cr = 83.789%,53Cr = 9.501%, and 54Cr = 2.365%. Cr-50 is radioactive but has such a long halflife—1.8×10+17 years—that it is considered to contribute about 4% to the total amount ofchromium found on Earth.

Origin of Name

From the Greek word chroma or chromos, meaning “color,” because of the many colors of its minerals and compounds.

출처

Chromium is the 21st most common element found in the Earth’s crust, and chromiumoxide (Cr2O3) is the 10th most abundant of the oxide compounds found on Earth. It is notfound in a free metallic state.The first source of chromium was found in the mineral crocoite. Today it is obtained fromthe mineral chromite (FeCr2O4), which is found in Cuba, Zimbabwe, South Africa, Turkey,Russia, and the Philippines. Chromite is an ordinary blackish substance that was ignored formany years. There are different grades and forms of chromium ores and compounds, based onthe classification of use of the element. Most oxides of chromium are found mixed with othermetals, such as iron, magnesium, or aluminum.Astronauts found that the moon’s basalt rocks contain several times more chromium thanis found in basalt rocks of Earth.

Characteristics

Chromium is a hard, brittle metal that, with difficulty, can be forged, rolled, and drawn,unless it is in a very pure form, in which case the chromium is easier to work with. It is anexcellent alloying metal with iron. Its bright, silvery property makes it an appropriate metal toprovide a reflective, non-corrosive attractive finish for electroplating.Various compounds of chromium exhibit vivid colors, such as red, chrome green, andchromate yellow, all used as pigments.

역사

Chromium was discovered in 1797 by Vauquelin, who prepared the metal the next year, chromium is a steel-gray, lustrous, hard metal that takes a high polish. The principal ore is chromite (FeCr2O4), which is found in Zimbabwe, Russia, South Africa, Turkey, Iran, Albania, Finland, Democratic Republic of Madagascar, the Philippines, and elsewhere. The U.S. has no appreciable chromite ore reserves. Chromium is usually produced by reducing the oxide with aluminum. Chromium is used to harden steel, to manufacture stainless steel, and to form many useful alloys. Much is used in plating to produce a hard, beautiful surface and to prevent corrosion. Chromium is used to give glass an emerald green color. It finds wide use as a catalyst. All compounds of chromium are colored; the most important are the chromates of sodium and potassium (K2CrO4) and the dichromates (K2Cr2O7) and the potassium and ammonium chrome alums, as KCr(SO4)2·12H2O. The dichromates are used as oxidizing agents in quantitative analysis, also in tanning leather. Other compounds are of industrial value; lead chromate is chrome yellow, a valued pigment. Chromium compounds are used in the textile industry as mordants, and by the aircraft and other industries for anodizing aluminum. The refractory industry has found chromite useful for forming bricks and shapes, as it has a high melting point, moderate thermal expansion, and stability of crystalline structure. Chromium is an essential trace element for human health. Many chromium compounds, however, are acutely or chronically toxic, and some are carcinogenic. They should be handled with proper safeguards. Natural chromium contains four isotopes. Twenty other isotopes are known. Chromium metal (99.95%) costs about $1000/kg. Commercial grade chromium (99%) costs about $75/kg.

용도

Chromium is used in the manufacture ofits alloys, such as chrome-steel or chromenickel-steel. It is also used for chromeplatingof other metals, for tanning leather,and in catalysts. It occurs in chromite ores(FeO·Cr2O3).

용도

In manufacture of chrome-steel or chrome-nickel-steel alloys (stainless steel), nonferrous alloys, heat resistant bricks for refractory furnaces. To greatly increase strength, hardness and resistance of metals to abrasion, corrosion and oxidation. For chrome plating of other metals; leather tanning; as pigment and mordant; wood preservative. Use of 51Cr as diagnostic aid see sodium chromate(VI).

용도

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.

정의

ChEBI: A chromium group element atom that has atomic number 24.

정의

A transition metal that occurs naturally as chromite (FeO·Cr2O3), large deposits of which are found in Zimbabwe. The ore is converted into sodium dichromate(VI) and then reduced with carbon to chromium(III) oxide and finally to metallic chromium with aluminum. Chromium is used in strong alloy steels and stainless steel and for plating articles. It is a hard silvery metal that resists corrosion at normal temperatures. It reacts slowly with dilute hydrochloric and sulfuric acids to give hydrogen and blue chromium(II) compounds, which quickly oxidize in air to green chromium(III) ions. The oxidation states are +6 in chromates (CrO42–) and dichromates (Cr2O72–), +3 (the most stable), and +2. In acidic solutions the yellow chromate(VI) ion changes to the orange dichromate(VI) ion. Dichromates are used as oxidizing agents in the laboratory; for example as a test for sulfur( IV) oxide (sulfur dioxide) and to oxidize alcohols.

정의

chromium: Symbol Cr. A hard silverytransition element; a.n. 24;r.a.m. 52.00; r.d. 7.19; m.p. 1857°C;b.p. 2672°C. The main ore ischromite (FeCr2O4). The metal has abody-centred-cubic structure. It is extractedby heating chromite withsodium chromate, from whichchromium can be obtained by electrolysis.Alternatively, chromite can be heated with carbon in an electricfurnace to give ferrochrome, whichis used in making alloy steels. Themetal is also used as a shiny decorativeelectroplated coating and in themanufacture of certain chromiumcompounds.
At normal temperatures the metalis corrosion-resistant. It reacts withdilute hydrochloric and sulphuricacids to give chromium(II) salts.These readily oxidize to the more stablechromium(III) salts. Chromiumalso forms compounds with the +6oxidation state, as in chromates,which contain the CrO42- ion. The elementwas discovered in 1797 byVauquelin.

일반 설명

Very hard gray solid with a metallic luster.

공기와 물의 반응

May be pyrophoric, as dust. Insoluble in water.

반응 프로필

Chromium reacts violently with NH4NO3, N2O2, Li, NO, KClO3, SO2 . Metal dusts when suspended in atmospheres of carbon dioxide may ignite and explode.

위험도

Hexavalent chromium compounds are questionable carcinogens and corrosive on tissue, resulting in ulcers and dermatitis on prolonged contact.

위험도

Even though chromium may be a necessary trace element in our diets, many of its compounds are very toxic when ingested. Some are very explosive when shocked or heated (e.g., chromium nitrate) or when in contact with organic chemicals. Dust from the mining of chromium ores, which is found in igneous rocks, is carcinogenic and can cause lung cancer, even when small amounts are inhaled. Workers in industries that produce and use chromium are subject to bronchogenic cancer if precautions are not taken.

건강위험

The toxicity of chromium alloys and compoundsvaries significantly. Chromium metaldoes not exhibit toxicity. Divalent and trivalentcompounds of chromium have a loworder of toxicity. Exposure to the dusts ofchromite or ferrochrome alloys may causelung diseases, including pneumoconiosis andpulmonary fibrosis.
Among all chromium compounds onlythe hexavalent salts are a prime health hazard.Cr6+ is more readily taken up bycells, than any other valence state of themetal. Occupational exposure to these compoundscan produce skin ulceration, dermatitis,perforation of the nasal septa, and kidneydamage. It can induce hypersensitivityreactions of the skin and renal tubular necrosis.Examples of hexavalent salts are thechromates and dichromates of sodium, potassium,and other metals. The water-solublehexavalent chromium salts are absorbed intothe bloodstream through inhalation. Manychromium(VI) compounds are carcinogenic,causing lung cancers in animals and humans.The carcinogenicity may be attributed tointracellular conversion of Cr6+ to Cr3+,which is biologically more active. The trivalentCr3+ ion can bind with nucleic acid andthus initiate carcinogenesis.
Paustenbach et al. (1996) reported a casestudy on the uptake and elimination ofCr(VI) in drinking water on a male volunteerwho ingested 2 L/day of water containing2 mg/L Cr(VI) for 17 consecutivedays. The total chromium was measured inurine, plasma and red blood cells. The eliminationhalf-life in plasma was 36 hoursand the bioavailability was estimated as 2%.The steady-state chromium concentrations inurine and blood were achieved after sevendays of Cr(VI) ingestion. This study furthermorerevealed that Cr(VI) in drinkingwater at concentrations below 10 mg/L couldbe completely reduced to Cr(III) prior tosystemic distribution. In a follow-up study,Kergen et al. (1997) examined the magnitudeof absorption, distribution and excretionof Cr(VI) in drinking water in human volunteersfollowing oral exposures to singleand repeated doses at 5 and 10 mg Cr(VI)/L.The data obtained from this study indicatedthat virtually all (> 99.7%) of the ingestedCr(VI) was reduced to Cr(III) before enteringthe blood stream. No toxicity was observed.The endogenous reducing agents within theupper GI tract and the blood were attributedto reduce hexavalent chromium into its trivalentstate and, thus, prevented any systemicuptake of Cr(VI). Such reduction appearedto be effective even under the fasting conditions.
Wise et al. (2002) investigated the cytotoxicityand clastogenicity of both water-insolubleand water-soluble Cr(VI) compounds in primaryhuman bronchial fibroblasts and foundthat they were overall cytotoxic and genotoxicto human lung cells. Although the genotoxicmechanisms of both may be mediated bysoluble Cr(VI) ions the water-insoluble saltsapparently are the potent carcinogens comparedto the water-soluble salts (Wise et al.2004). Exposure to Cr(VI) enhanced the bindingof polycyclic aromatic hydrocarbons toDNA in human lung cells (Feng et al. 2003).Hexavalent chromium has been found to besynergistic to benzo a pyrene diol epoxide onmutagenesis and cell transformation.
The catalytic effect of iron on enhancingthe rate of reduction of Cr(VI) byhuman microsomes has been reported earlier(Myers and Myers 1998). Various formsof exogenous iron markedly enhanced bothliver and lung microsomal rates of Cr(VI)reduction. Small increases in intracellulariron have shown to cause large increases inin the rate and extent of Cr(VI) reduction.Thus, individuals exposed simultaneously toCr(VI) and agents that may increase intracellulariron could, therefore, be at potentiallygreater risk for toxicity and carcinogenicityof Cr(VI).

화재위험

Non-combustible, substance itself does not burn but may decompose upon heating to produce corrosive and/or toxic fumes. Some are oxidizers and may ignite combustibles (wood, paper, oil, clothing, etc.). Contact with metals may evolve flammable hydrogen gas. Containers may explode when heated.

공업 용도

An elementary metal, chromium (symbol Cr)is used in stainless steels, heat-resistant alloys,high-strength alloy steels, electrical-resistancealloys, wear-resistant and decorative electroplating,and, in its compounds, for pigments,chemicals, and refractories. The specific gravityis 6.92, melting point 1510°C, and boiling point2200°C. The color is silvery white with a bluishtinge. It is an extremely hard metal; the electrodepositedplates have a hardness of 9 Mohs.It is resistant to oxidation, is inert to HNO3, butdissolves in HCl and slowly in H2SO4. At temperaturesabove 816°C, it is subject to intergranularcorrosion.
Chromium occurs in nature only in combination.Its chief ore is chromite, from which itis obtained by reduction and electrolysis. It ismarketed for use principally in the form of masteralloys with iron or copper.Most pure chromium is used for alloyingpurposes such as the production of Ni–Cr orother nonferrous alloys where the use of thecheaper ferrochrome grades of metal is not possible.In metallurgical operations such as theproduction of low-alloy and stainless steels, thechromium is added in the form of ferrochrome,an electric-arc furnace product that is the formin which most chromium is consumed.
Its bright color and resistance to corrosion makechromium highly desirable for plating plumbingfixtures, automobile radiators and bumpers,and other decorative pieces. Unfortunately,chrome plating is difficult and expensive. Itmust be done by electrolytic reduction ofdichromate in H2SO4 solution. It is customary,therefore, to first plate the object with copper,then with nickel, and finally, with chromium.

잠재적 노출

Chromium metal is used in stainless and other alloy steels to impart resistance to corrosion, oxidation, and for greatly increasing the durability of metals; for chrome plating of other metals.

응급 처치

Move victim to fresh air. Call 911 or emergency medical service. Give artificial respiration if victim is not breathing. Do not use mouth-to-mouth method if victim ingested or inhaled the substance; give artificial respiration with the aid of a pocket mask equipped with a one-way valve or other proper respiratory medical device. Administer oxygen if breathing is difficult. Remove and isolate contaminated clothing and shoes. In case of contact with substance, immediately flush skin or eyes with running water for at least 20 minutes. For minor skin contact, avoid spreading material on unaffected skin. Keep victim warm and quiet. Effects of exposure (inhalation, ingestion, or skin contact) to substance may be delayed. Ensure that medical personnel are aware of the material(s) involved and take precautions to protect themselves. Medical observation is recommended for 24 to 48 hours after breathing overexposure, as pulmonary edema may be delayed. As first aid for pulmonary edema, a doctor or authorized paramedic may consider administering a drug or other inhalation therapy.

운송 방법

UN3089 Metal powders, flammable, n.o.s., Hazard Class: 4.1; Labels: 4.1-Flammable solid. UN1759 Corrosive solids, n.o.s., Hazard class: 8; Labels: 8-Corrosive material, Technical Name required

비 호환성

Dust may be pyrophoric in air. Chromium metal (especially in finely divided or powder form) and insoluble salts reacts violently with strong oxidants, such as hydrogen peroxide, causing fire and explosion hazard. Reacts with diluted hydrochloric and sulfuric acids. Incompatible with alkalis and alkali carbonates

폐기물 처리

Recovery and recycling is a viable alternative to disposal for chromium in plating wastes; tannery wastes; cooling tower blowdown water and chemical plant wastes.

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