Chromium, ib tug tshuaj caij: hauj lwm, zog, thiab tus cwj pwm ntawm mis

Chromium - tshuaj caij nrog atomic tooj 24. Qhov no nyuaj, ci, steel-grey hlau uas yog zoo polished, thiab tsis tarnish. Siv nyob rau hauv alloys xws li stainless steel, thiab raws li ib tug txheej. tib neeg lub cev yuav tsum tau ib tug me me npaum li cas ntawm trivalent chromium rau qab zib metabolism tab sis Cr (VI) yog ib co tshuaj lom.

Ntau chromium tebchaw xws li chromium oxide (III) thiab cov hlau lead chromate, yog lug dawb lias thiab siv nyob rau hauv cov xim tsev thiab pigments. Ruby liab xim vim lub xub ntiag ntawm no tshuaj caij. Tej yam tshuaj, tshwj xeeb tshaj yog poov tshuaj dichromate thiab sodium oxidants yog siv rau lub oxidation ntawm cov organic tebchaw, thiab (nrog sulfuric acid) los ntxuav khob iav. Nyob rau hauv tas li ntawd, chromium oxide (VI) yog siv nyob rau hauv qhuav ntawm magnetic daim kab xev.

Discovery thiab etymology

Keeb kwm ntawm lub foundations ntawm ib tug tshuaj caij yog chromium. Nyob rau hauv 1761, Johann Gottlob Lehmann pom nyob rau hauv lub Ural roob txiv kab ntxwv-liab mineral, thiab hu ua nws "lub Siberian liab lead." Txawm hais tias nws twb tau yuam qhia raws li ib tug ua compound nrog selenium thiab hlau, cov khoom yuav ua tau ib tug ua chromate tshuaj mis PbCrO _4. Niaj hnub no nws yog lub npe hu raws li ib tug mineral krokont.

Nyob rau hauv 1770, Peter Simon Pallás mus xyuas qhov chaw uas Lehman pom ib tug liab lead mineral uas muaj pab tau heev thaj chaw ntawm xim nyob rau hauv cov xim tsev. Kev siv ntawm Siberian liab lead raws li ib tug xim tau sai kev loj hlob. Nyob rau hauv tas li ntawd, txoj kev kaj lug daj xim ntawm krokonta los ua cob xub.

Nyob rau hauv 1797, Nicolas-Lui Voklen tau txais qauv ntawm liab lead ore. Krokonta los ntawm nws cov nws nrog hydrochloric acid yog CrO ₃ oxide. Chromium raws li ib tug tshuaj caij tau cais nyob rau hauv 1798. Vauquelin tau nws los ntawm cua sov rau cov oxide nrog charcoal. Nws kuj muaj peev xwm mus ntes ib co kua nplaum ntawm chromium nyob rau hauv precious pob zeb xws li ruby thiab Emerald.

Nyob rau hauv lub 1800s thiab Kr mas siv nyob rau hauv cov xim thiab tawv ntsev. Niaj hnub no 85% ntawm cov hlau siv nyob rau hauv lub alloys. Tus so yog siv nyob rau hauv lub tshuaj ua lag luam, cov siv thiab ua cov refractories thiab foundry kev lag luam.

Hais chromium tshuaj caij sau raws nkaus Ii mus rau lub Greek χρῶμα, lub ntsiab lus "xim", vim hais tias ib tug plurality cov dawb lias tebchaw uas muaj peev xwm yuav npaj therefrom.

Mining thiab ntau lawm

Caij los ntawm chromite (FeCr ₂ O _4). Hais txog ib nrab ntawm no ore yog mined nyob rau hauv South Africa. Nyob rau hauv tas li ntawd, Kazakhstan, Is Nrias teb thiab Qaib Cov Txwv yog nws loj producers. Explored deposits ntawm chromite txaus, tab sis lawv yog ib thaj nyuag feeb meej nyob rau hauv Kazakhstan thiab yav qab teb teb chaws Africa.

Cov deposits ntawm haiv neeg chromium hlau yog tsis tshua muaj, tab sis lawv muaj. Piv txwv li, nws yog ua nyob rau kuv "Successful" nyob rau hauv Russia. Nws yog ib tug kimberlite yeeb nkab nplua nuj nyob rau hauv diamonds, thiab cov txo chaw pab rau hauv daim ntawv ntawm ntshiab chromium thiab diamonds.

Kom muaj zus tau tej cov hlau chromite ore yog kho nrog ib tug molten alkali (sodium hydroxide, NaOH). Qhov no ntaub ntawv sodium chromate (Na ₂ CrO _4), uas yog txo nrog carbon rau Kr ₂ O ₃ oxide. Cov hlau oxide yog tau los ntawm cua sov nyob rau hauv lub xub ntiag ntawm txhuas los yog pob zeb ntais.

txog 15 lab tonnes ntawm chromite ore tau ua nyob rau hauv 2000 xyoo, uas tau ua tiav rau hauv 4 lab tonnes ntawm ferrochrome, 70% muaj chromium-hlau alloy, kwv yees li kev ua lag luam tus nqi yog $ 2.5 Bln.

Ntsiab nta

Yam ntxwv tshuaj caij chromium yog vim lub fact tias nws yog ib txoj kev hloov hlau ntawm plaub lub sij hawm ntawm lub periodic rooj thiab nyob nruab nrab ntawm vanadium thiab manganese. Muaj nyob rau hauv lub VI pab pawg neeg. Nws melts ntawm 1907 ° C. Nyob rau hauv lub xub ntiag ntawm oxygen chrome sai ntaub ntawv ib tug nyias txheej ntawm oxide uas tiv thaiv lub hlau los ntawm ntxiv cov tshuaj tiv thaiv nrog rau oxygen.

Raws li ib tug hloov lub caij, nws reacts nrog tshuaj nyob rau hauv txawv ratios. Yog li nws cov ntaub ntawv sib txuas nrog ib tug txawv degree ntawm oxidation. Chromium - tshuaj caij nrog tseem ceeb lub xeev +2, +3 thiab + 6, ntawm uas 3 yog lub feem ntau ruaj khov. Nyob rau hauv tas li ntawd, nyob rau hauv uas tsis tshua muaj mob, muaj yog lub xeev ntawm +1, +4 thiab +5. chromium tebchaw nyob rau hauv lub oxidation xeev + 6 muaj zog oxidizers.

Yuav ua li cas xim yog chrome? Tshuaj caij muab Anodized txhuas ruby Hawj txawm. Kr ₂ O ₃ yog siv rau hlau polishing, nws kuj yog siv raws li ib tug xim hu ua "chrome zaub ntsuab". Nws ntsev tsuas iav nyob rau hauv kab tho ntsuab. Chromium - ib tug tshuaj caij uas nws muaj ua rau cov ruby liab. Yog li ntawd nws yog siv nyob rau hauv qhuav ntawm cov khoom cua rubies.

isotopes

Isotopes muaj chromium atomic hnyav los ntawm 43 mus 67. Feem ntau, active tshuaj caij muaj peb ruaj khov ntaub ntawv: ⁵² Cr, ⁵³ Kr thiab ⁵⁴ Cr. Ntawm no, feem ntau ⁵² Cr (83,8% ntawm tag nrho cov natural chromium). Nyob rau hauv tas li ntawd, radioisotopes piav 19, ntawm uas lub feem ntau ruaj khov yog ⁵⁰ Kr nrog ib tug ib nrab-lub neej ntau dua tshaj 1,8x10 ¹⁷ xyoo. Nyob rau hauv ⁵¹ Kr ib nrab-lub neej - 27,7 hnub, thiab nyob rau hauv tag nrho cov lwm yam neeg isotopes tsis pub tshaj 24 teev, thiab feem ntau ntawm lawv nws kav tsawg tshaj li ib feeb. Lub caij kuj muaj ob tug meta.

Chromium isotopes nyob rau hauv lub ntiaj teb ua kiav txhab, feem ntau yog nrog isotope ntawm manganese, uas yog siv nyob rau hauv geology. ⁵³ Kr tsim los ntawm cov neeg lwj ntawm ⁵³ Mn. Qhov ratio ntawm Mn / Kr isotope txhawb lwm yam ntaub ntawv hais txog rau hauv thaum ntxov keeb kwm ntawm lub solar system. Cov kev hloov nyob rau hauv lub proportions ⁵³ Cr / ⁵² Kr thiab Mn / Kr ntawm txawv meteorites proves tias tshiab nuclei raug teem tam sim ntawd ua ntej lub tsim ntawm lub solar system.

Tshuaj caij chromium: zog, lub tebchaw ntawm mis

Chromium oxide (III) Kr ₂ O _3, kuj hu ua sesquioxide, yog ib tug ntawm cov plaub oxide ntawm no tshuaj caij. Nws yog tau los ntawm chromite. Tiabsis cov ntsuab feem ntau hu ua "chrome ntsuab," thaum siv raws li ib tug xim rau painting rau txha hniav laus thiab iav. Lub oxide yuav ua neej nyob rau hauv acids los tsim ib lub ntsev, thiab cov molten alkali - chromites.

poov tshuaj dichromate

K ₂ Kr ₂ O ₇ yog ib tug haib oxidizing neeg sawv cev thiab nws yog najnpawb raws li ib tug txhais tau tias rau tu glassware los ntawm organics. Rau lub hom phiaj no nws yog siv nyob rau hauv ib tug nyeem tov ntawm concentrated sulfuric acid. Tej zaum, li cas los xij, nws yog hloov nrog sodium dichromate, raws li nyob rau hauv lub siab solubility ntawm lub yav tas. Dhau li ntawd, nws muaj peev xwm tswj cov txheej txheem ntawm oxidation ntawm cov organic tebchaw los ntawm hloov ib tug thawj cawv rau ib tug aldehyde thiab ces mus rau cov pa roj carbon dioxide.

poov tshuaj dichromate chromium yuav ua rau dermatitis. Chrome yog tej zaum qhov ua rau ntawm sensitization ua rau dermatitis txoj kev loj hlob, tshwj xeeb tshaj yog nyob rau hauv lub ob txhais tes thiab caj npab, uas yog mob thiab nyuaj yuav tsum tau kho. Ib yam li lwm lub tebchaw ntawm Cr (VI), poov tshuaj dichromate carcinogenic. Yuav tsum tau daws nrog cov hnab looj tes thiab kom tsim nyog tiv thaiv.

chromic acid

Hypothetical compound muaj cov qauv H ₂ CrO _4. Tsis Chrome los yog acidic dichromate tsis tshwm sim nyob rau hauv cov xwm, tab sis lawv cov anions yog pom nyob rau hauv ib tug ntau yam ntawm cov ntaub ntawv. "Chromic acid" uas yuav muaj nyob rau muag, nyob rau hauv qhov tseeb nws yog ib tug acid anhydride - trioxide CrO _3.

Lead chromate (II)

PbCrO ₄ muaj ib tug kaj daj xim thiab yog suab insoluble nyob rau hauv cov dej. Vim li no, nws tau pom daim ntawv thov raws li ib tug coloring xim, hu ua "daj crowns."

Kr thiab pentavalent peb

Chrome yog distinguished los ntawm nws muaj peev xwm mus tsim pentavalent kev twb kev txuas. Tiabsis cov tsim Cr (I) thiab lub hydrocarbon radical. Pentavalent daim ntawv cog lus tsim ntawm chromium atoms. Nws mis yuav tsum muab sau raws li Ar-Kr-Kr-Ar, nyob rau Ar nruab nrab yog ib txog kev uas muaj ntxhiab pab pawg neeg.

daim ntawv thov

Chromium - tshuaj caij uas nws cov khoom nws muab ntau yam ntaub ntawv sau npe, ib co kev uas muaj qhia hauv qab no.

Co nws lub txiaj ntsim kuj yuav corrosion thiab ib tug glossy nto. Yog li ntawd, ib feem ntawm cov chrome alloys xws li stainless steel, siv piv txwv li nyob rau hauv lub cutlery. Nws kuj yog siv rau kev thov cov chrome txheej.

Chromium yog ib lub hauv paus rau ntau yam kev tshua. Vim hais tias nws yuav ua rau tuaj pwm rau tus firing ntawm bricks. Nws ntsev tanned tawv nqaij. poov tshuaj bichromate yog siv rau cov oxidation uas muaj organic tebchaw xws li alcohols thiab aldehydes, raws li zoo raws li rau tu glassware. Nws ua hauj lwm pab raws li ib tug kho tus neeg saib xyuas rau dyeing ntaub, thiab nws kuj yog siv nyob rau hauv photography thiab printing.

CrO ₃ siv rau zus tau tej cov magnetic tapes (piv txwv li, cov ntaub ntawv) uas muaj zoo dua cov yam ntxwv tshaj films nrog hlau oxide.

Lub luag hauj lwm nyob rau hauv biology ua

Trivalent chromium - cov tshuaj ntsiab yuav tsum tau rau cov metabolism hauv qab zib nyob rau hauv tib neeg. Rau hauv sib piv, hexavalent Kr yog heev tshuaj lom.

precautionary ntsuas

Nws yog xim hlau chromium compound Cr (III), yog feem ntau tsis xav tau tej kev kho, tab sis ntaub ntawv uas muaj Cr (VI), yuav ua tau lom thaum nqos los yog nqus tau pa. Feem ntau cov zoo li tshuaj yog irritating mus rau lub qhov muag, daim tawv nqaij thiab qog ua kua week. Nrog txuas ntxiv raug ntawm chromium tebchaw (VI) tej zaum yuav ua kev puas tsuaj rau lub qhov muag yog hais tias tsis kho kom zoo. Nyob rau hauv tas li ntawd, ib tug paub tias carcinogen. Ib tug tuag koob tshuaj ntawm cov tshuaj lub caij - ib nrab ib tug teaspoon. Raws li cov tswv yim pom zoo ntawm lub ntiaj teb Health Organization, lub siab tshaj plaws permissible concentration ntawm Cr (VI) nyob rau hauv cov dej haus yog 0.05 mg ib liter.

Txij li thaum lub chromium tebchaw yog siv nyob rau hauv dyes thiab rau tanning tawv, lawv yog feem ntau pom nyob rau hauv cov av thiab nqhuab uas muaj chaw uas yuav tsum tau tej tu tej thiab rov qab. Primer muaj Cr (VI), yog tseem lug siv nyob rau hauv lub Aerospace kev lag luam thiab cov automotive kev lag luam.

caij zog

Cov yooj yim lub cev thaj chaw ntawm chromium yog raws li nram no:

• Lub atomic tooj ntawm 24.
• Atomic yuag: 51,996.
• Melting point: 1890 ° C.
• Boiling point: 2482 ° C.
• Cov oxidation lub xeev ntawm +2, +3, + 6.
• Electron configuration: [Ar] 3d ⁵ 4s ^1.