Ntau yam tshuaj sib txawv tau paub hauv ntiaj teb: txog ntau pua lab. Thiab txhua tus ntawm lawv, zoo li tib neeg, yog tus kheej. Nws yog tsis yooj yim sua kom nrhiav tau ob yam khoom uas yuav muaj tib yam tshuaj thiab lub cev muaj zog nrog sib txawv muaj pes tsawg leeg.
Ib qho ntawm cov khoom tsis muaj txiaj ntsig zoo tshaj plaws uas muaj nyob hauv ntiaj teb yog carbides. Hauv tsab xov xwm no, peb yuav tham txog lawv cov qauv, lub cev thiab cov khoom siv tshuaj lom neeg, kev siv thiab tshuaj xyuas cov intricacies ntawm lawv cov khoom. Tab sis ua ntej, me ntsis txog keeb kwm ntawm kev tshawb pom.
History
Hlau carbides, cov qauv uas peb yuav muab hauv qab no, tsis yog cov khoom sib xyaw ua ke. Qhov no yog vim qhov tseeb tias lawv cov molecules zoo li decompose thaum cuam tshuam nrog dej. Yog li ntawd, nws tsim nyog tham txog thawj zaug sim ua ke carbides ntawm no.
Los ntawm 1849 muaj cov ntaub ntawv hais txog kev sib txuas ntawm silicon carbide, tab sis qee qhov kev sim no tseem tsis tau paub. Kev tsim khoom loj tau pib xyoo 1893 los ntawm Asmeskas kws tshuaj xyuas Edward Acheson hauv cov txheej txheem uas tom qab ntawd muaj npe tom qab nws.
Keeb kwm ntawm kev sib txuas ntawm calcium carbide kuj tsis txawv ntawm cov ntaub ntawv loj. Nyob rau hauv 1862, German chemist Friedrich Wöhler tau txais nws los ntawm cua sov alloyed zinc thiab calcium nrog thee.
Tam sim no cia peb mus rau ntu nthuav dav ntxiv: tshuaj lom neeg thiablub cev muaj zog. Tom qab tag nrho, nws yog nyob rau hauv lawv tias tag nrho cov ntsiab lus ntawm kev siv cov chav kawm ntawm cov tshuaj no dag.
Lub cev muaj zog
Txhua yam carbides yog qhov txawv ntawm lawv qhov nyuaj. Piv txwv li, ib qho ntawm cov khoom nyuaj tshaj plaws ntawm Mohs nplai yog tungsten carbide (9 tawm ntawm 10 cov ntsiab lus tau). Tsis tas li ntawd, cov tshuaj no yog refractory heev: lub melting point ntawm lawv mus txog ob txhiab degrees.
Feem ntau cov carbides yog tshuaj inert thiab cuam tshuam nrog me me ntawm cov tshuaj. Lawv yog insoluble nyob rau hauv tej kuab tshuaj. Txawm li cas los xij, kev sib cais tuaj yeem suav tias yog kev cuam tshuam nrog dej nrog kev puas tsuaj ntawm daim ntawv cog lus thiab tsim cov hlau hydroxide thiab hydrocarbon.
Peb yuav tham txog cov tshuaj tiv thaiv zaum kawg thiab ntau lwm yam kev hloov pauv tshuaj lom neeg uas muaj carbides nyob rau ntu tom ntej.
tshuaj muaj zog
Yuav luag txhua carbides cuam tshuam nrog dej. Qee qhov - yooj yim thiab tsis muaj cua sov (piv txwv li, calcium carbide), thiab qee qhov (piv txwv li, silicon carbide) - los ntawm cua sov dej vapor mus rau 1800 degrees. Lub reactivity nyob rau hauv cov ntaub ntawv no yog nyob ntawm qhov xwm ntawm daim ntawv cog lus nyob rau hauv lub compound, uas peb yuav tham tom qab. Hauv cov tshuaj tiv thaiv nrog dej, ntau yam hydrocarbons raug tsim. Qhov no tshwm sim vim hais tias cov hydrogen muaj nyob rau hauv dej ua ke nrog cov pa roj carbon nyob rau hauv cov carbide. Nws tuaj yeem nkag siab qhov twg hydrocarbon yuav tig tawm (thiab ob qho tib si saturated thiab unsaturated compounds tuaj yeem tig tawm) raws li qhov muaj txiaj ntsig ntawm cov pa roj carbon uas muaj nyob hauv cov khoom qub. Piv txwv li, yog tias kojpeb muaj calcium carbide, cov mis uas yog CaC2, peb pom tias nws muaj cov ion C22-. Qhov no txhais tau hais tias ob lub hydrogen ions nrog ib + nqi tuaj yeem txuas rau nws. Yog li, peb tau txais cov compound C2H2 - acetylene. Nyob rau hauv tib txoj kev, los ntawm ib tug compound xws li txhuas carbide, cov mis ntawm uas yog Al4C3, peb tau CH 4. Ua cas tsis C3H12, koj nug? Tom qab tag nrho, cov ion muaj nqi ntawm 12-. Qhov tseeb yog tias qhov siab tshaj plaws ntawm hydrogen atoms yog txiav txim los ntawm cov mis 2n + 2, qhov twg n yog tus naj npawb ntawm carbon atoms. Qhov no txhais tau hais tias tsuas yog ib qho kev sib xyaw nrog cov mis C3H8 (propane) tuaj yeem muaj nyob, thiab cov ion nrog tus nqi ntawm 12- lwj rau hauv peb. ions nrog tus nqi ntawm 4-, uas muab methane molecules thaum ua ke nrog protons.
Oxidation cov tshuaj tiv thaiv ntawm carbides yog qhov nthuav. Lawv tuaj yeem tshwm sim ob qho tib si thaum raug cov khoom sib xyaw ua ke ntawm oxidizing cov neeg ua haujlwm, thiab thaum lub sij hawm sib xyaw ua ke hauv cov pa oxygen. Yog tias txhua yam pom tseeb nrog oxygen: ob lub oxides tau txais, ces nrog rau lwm cov oxidizing agents nws yog qhov nthuav dua. Nws tag nrho yog nyob ntawm qhov xwm ntawm cov hlau uas yog ib feem ntawm cov carbide, nrog rau qhov xwm ntawm oxidizing tus neeg sawv cev. Piv txwv li, silicon carbide, cov mis uas yog SiC, thaum interacting nrog ib tug sib tov ntawm nitric thiab hydrofluoric acids, tsim hexafluorosilicic acid nrog kev tso tawm ntawm carbon dioxide. Thiab thaum nqa tawm tib cov tshuaj tiv thaiv, tab sis nrog tsuas yog nitric acid, peb tau txais silicon oxide thiab carbon dioxide. Halogens thiab chalcogens tuaj yeem raug hu ua oxidizing agents. Txhua tus carbide cuam tshuam nrog lawv, cov tshuaj tiv thaiv mis tsuas yog nyob ntawm nws cov qauv.
Hlau carbides, cov qauv uas peb tau txiav txim siab, nyob deb ntawm cov neeg sawv cev ntawm cov chav kawm ntawm cov tebchaw. Tam sim no peb yuav ua tib zoo saib xyuas txhua qhov kev lag luam tseem ceeb ntawm cov chav kawm no thiab tom qab ntawd tham txog lawv daim ntawv thov hauv peb lub neej.
YDab tsi yog carbides?
Nws hloov tawm tias carbide, nws cov qauv, hais, CaC2, sib txawv hauv cov qauv ntawm SiC. Thiab qhov txawv yog feem ntau nyob rau hauv qhov xwm ntawm daim ntawv cog lus ntawm atoms. Hauv thawj kis, peb tab tom soj ntsuam nrog ntsev zoo li carbide. Cov chav kawm ntawm cov tebchaw no muaj npe vim tias nws ua tau zoo li ntsev, uas yog, nws muaj peev xwm sib cais rau hauv ions. Xws li daim ntawv cog lus ionic tsis muaj zog heev, uas ua rau nws yooj yim los nqa tawm cov tshuaj tiv thaiv hydrolysis thiab ntau lwm yam kev hloov pauv, suav nrog kev cuam tshuam ntawm ions.
Lwm yam, tej zaum tseem ceeb tshaj plaws, hom carbide yog covalent carbide, xws li SiC lossis WC. Lawv yog cov yam ntxwv los ntawm kev kub ceev thiab lub zog. Tsis tas li refractory thiab inert rau dilute tshuaj.
Tseem muaj cov hlau zoo li carbides. Lawv tuaj yeem suav tau tias yog cov hlau alloys nrog carbon. Ntawm cov no, ib tus tuaj yeem paub qhov txawv, piv txwv li, cementite (hlau carbide, cov mis uas txawv, tab sis qhov nruab nrab nws yog kwv yees li hauv qab no: Fe 3 C) lossis cam khwb cia hlau. Lawv muaj cov tshuaj lom neeg ua haujlwm nruab nrab ntawm qib ntawm ionic thiab covalent carbides.
Txhua yam ntawm cov subspecies ntawm cov chav kawm ntawm cov tshuaj sib txuas uas peb tab tom tham muaj nws tus kheej siv tau. Yuav thov li cas thiab qhov twgtxhua tus, peb mam li tham hauv nqe lus tom ntej.
Kev siv cov carbides
Raws li peb tau tham lawm, covalent carbides muaj ntau yam kev siv tswv yim. Cov no yog cov khoom siv abrasive thiab txiav, thiab cov ntaub ntawv sib xyaw siv nyob rau hauv ntau qhov chaw (piv txwv li, ua ib qho ntawm cov khoom siv ua lub cev armor), thiab nws pib qhov chaw, thiab cov khoom siv hluav taws xob, thiab cov khoom cua sov, thiab lub zog nuclear. Thiab qhov no tsis yog ib daim ntawv teev tag nrho cov ntawv thov rau cov superhard carbides.
S alt-forming carbides muaj daim ntawv thov nqaim tshaj plaws. Lawv cov tshuaj tiv thaiv nrog dej yog siv los ua ib txoj hauv kev kuaj los tsim cov hydrocarbons. Peb twb tau tham txog yuav ua li cas qhov no tshwm sim saum toj no.
Nrog rau covalent, hlau zoo li carbides muaj daim ntawv thov dav tshaj plaws hauv kev lag luam. Raws li peb twb tau hais lawm, xws li hom hlau zoo li lub tebchaw uas peb tab tom tham yog cov hlau, cam khwb cia hlau thiab lwm yam hlau sib txuas nrog cov pa roj carbon. Raws li txoj cai, cov hlau pom nyob rau hauv cov khoom no belongs rau chav kawm ntawm d-hlau. Tias yog vim li cas nws yog inclined los tsim tsis covalent bonds, tab sis, raws li nws yog, yuav tsum tau nkag mus rau hauv cov qauv ntawm cov hlau.
Nyob rau hauv peb lub tswv yim, cov tebchaw saum toj no muaj ntau tshaj li kev siv tswv yim txaus. Tam sim no cia peb saib cov txheej txheem kom tau txais lawv.
Kev tsim cov carbides
Thawj ob hom carbides uas peb tau tshuaj xyuas, uas yog covalent thiab ntsev zoo li, feem ntau tau txais hauv ib txoj kev yooj yim: los ntawm cov tshuaj tiv thaiv ntawm oxide ntawm lub caij thiab coke ntawm qhov kub thiab txias. Nyob rau tib lub sijhawm, ib feemcoke, muaj cov pa roj carbon monoxide, ua ke nrog ib qho atom ntawm cov khoom hauv cov oxide, thiab tsim cov carbide. Lwm qhov "siv" oxygen thiab tsim carbon monoxide. Txoj kev no yog siv zog heev, vim nws yuav tsum tau tswj qhov kub thiab txias (kwv yees li 1600-2500 degrees) hauv thaj tsam tshuaj tiv thaiv.
Lwm cov tshuaj tiv thaiv yog siv kom tau txais qee hom kev sib txuas. Piv txwv li, lub decomposition ntawm ib tug compound, uas thaum kawg muab ib tug carbide. Cov qauv tshuaj tiv thaiv nyob ntawm qhov sib xyaw tshwj xeeb, yog li peb yuav tsis tham txog nws.
Ua ntej peb xaus peb tsab xov xwm, cia peb tham txog qee cov carbides nthuav thiab tham txog lawv kom meej ntxiv.
Nco ntsoov sib txuas
Sodium carbide. Cov mis rau cov tshuaj no yog C2Na2. Qhov no tuaj yeem xav txog ntau dua li acetylenide (piv txwv li, cov khoom ntawm kev hloov cov hydrogen atoms hauv acetylene los ntawm sodium atoms), es tsis yog carbide. Cov tshuaj formula tsis muaj kev cuam tshuam tag nrho cov subtleties, yog li lawv yuav tsum tau nrhiav hauv cov qauv. Qhov no yog ib yam khoom muaj zog heev thiab nyob rau hauv ib qho kev sib cuag nrog dej nws nquag cuam tshuam nrog nws nrog tsim ntawm acetylene thiab alkali.
Magnesium carbide. Formula: MgC2. Cov txheej txheem kom tau txais cov khoom siv txaus txaus no yog qhov txaus siab. Ib qho ntawm lawv yog sintering ntawm magnesium fluoride nrog calcium carbide ntawm qhov kub thiab txias. Vim li no, ob yam khoom tau txais: calcium fluoride thiab carbide peb xav tau. Cov mis rau cov tshuaj tiv thaiv no yooj yim heev, thiab koj tuaj yeem nyeem nws hauv cov ntawv tshwj xeeb yog tias koj xav tau.
Yog tias koj tsis paub meej txog qhov muaj txiaj ntsig ntawm cov khoom uas tau nthuav tawm hauv kab lus, ces cov hauv qab noseem rau koj.
Yuav ua li cas thiaj muaj txiaj ntsig hauv lub neej?
Zoo, ua ntej ntawm tag nrho, kev paub txog tshuaj lom neeg tsis tuaj yeem ua tsis tau zoo. Nws yog ib txwm zoo dua los ua tub rog nrog kev paub ntau dua li tsis muaj nws. Qhov thib ob, qhov ntau koj paub txog qhov muaj nyob ntawm qee cov tebchaw, qhov zoo dua koj nkag siab txog cov txheej txheem ntawm lawv cov tsim thiab cov cai uas tso cai rau lawv nyob.
Ua ntej yuav mus txog qhov kawg, kuv xav muab ob peb lub tswv yim rau kev kawm txog cov ntaub ntawv no.
Yuav kawm li cas?
Yooj yim heev. Nws tsuas yog ib ceg ntawm chemistry xwb. Thiab nws yuav tsum tau kawm nyob rau hauv chemistry phau ntawv. Pib nrog cov ntaub ntawv hauv tsev kawm ntawv thiab mus rau cov ntaub ntawv tob tob los ntawm cov phau ntawv kawm hauv tsev kawm ntawv thiab cov phau ntawv siv.
Zoo kawg
Lub ncauj lus no tsis yooj yim thiab dhuav li nws zoo nkaus li thaum xub thawj siab ib muag. Chemistry yeej ib txwm nthuav yog tias koj pom koj lub hom phiaj hauv nws.
