Kev hloov ntawm ib yam khoom mus rau lwm qhov nrog kev tsim cov tshuaj tshiab hu ua tshuaj tiv thaiv. Kev nkag siab txog cov txheej txheem no yog qhov tseem ceeb heev rau lub neej ntawm tib neeg, vim tias nrog nws cov kev pab koj tuaj yeem tau txais ntau yam khoom tsim nyog thiab muaj txiaj ntsig zoo uas pom muaj nyob hauv cov xwm txheej me me lossis tsis muaj nyob hauv lawv daim ntawv ntuj. Ntawm cov tseem ceeb tshaj plaws yog cov tshuaj tiv thaiv redox (cov ntawv luv OVR lossis redox). Lawv yog tus cwj pwm los ntawm kev hloov pauv hauv oxidation xeev ntawm atoms lossis ions.
txheej txheem tshwm sim thaum lub sijhawm tshuaj tiv thaiv
Thaum lub sijhawm cov tshuaj tiv thaiv, ob qhov txheej txheem tshwm sim - oxidation thiab txo qis. Thawj ntawm lawv yog tus cwj pwm los ntawm kev pub dawb ntawm cov hluav taws xob los ntawm kev txo cov neeg sawv cev (cov neeg pub dawb) nrog kev nce hauv lawv lub xeev oxidation, qhov thib ob los ntawm kev sib ntxiv ntawm electrons los ntawm oxidizing agents (acceptors) nrog kev txo qis hauv lawv lub xeev oxidation. Cov tshuaj txo qis tshaj plaws yog cov hlau thiab cov hlau tsis muaj hlau nyob hauv lub xeev oxidation qis tshaj (hydrogen sulfide, ammonia). yamoxidizing agents yog halogens, nitrogen, oxygen, nrog rau cov khoom uas muaj cov khoom nyob rau hauv lub siab tshaj plaws oxidation xeev (nitric los yog sulfuric acid). Atoms, ions, molecules tuaj yeem pub dawb lossis nce electrons.
Ua ntej 1777, nws tau xav tias oxidation ua rau poob ntawm cov khoom siv hluav taws xob tsis pom hu ua phlogiston. Txawm li cas los xij, txoj kev xav combustion tsim los ntawm A. Lavoisier ntseeg cov kws tshawb fawb tias oxidation tshwm sim thaum cuam tshuam nrog oxygen, thiab kev txo qis tshwm sim nyob rau hauv qhov kev txiav txim ntawm hydrogen. Tsuas yog tom qab ib pliag nws tau pom tseeb tias tsis yog hydrogen thiab oxygen nkaus xwb tuaj yeem cuam tshuam cov tshuaj tiv thaiv redox.
Oxidation
Cov txheej txheem ntawm oxidation tuaj yeem tshwm sim hauv cov kua thiab roj theem, nrog rau ntawm cov khoom khib nyiab. Lub luag haujlwm tshwj xeeb yog ua los ntawm electrochemical oxidation tshwm sim hauv cov kev daws teeb meem lossis melts ntawm lub anode (ib qho electrode txuas nrog tus ncej zoo ntawm lub zog hluav taws xob). Piv txwv li, thaum fluorides yaj los ntawm electrolysis (decomposition ntawm ib yam khoom rau hauv nws cov ntsiab lus ntawm electrodes), qhov muaj zog tshaj inorganic oxidizing tus neeg sawv cev, fluorine, yog tau.
Ib qho piv txwv classic ntawm oxidation yog combustion hauv huab cua thiab ntshiab oxygen. Ntau yam khoom muaj peev xwm ntawm cov txheej txheem no: hlau thiab tsis yog hlau, organic thiab inorganic compounds. Ntawm cov tswv yim tseem ceeb yog kev sib xyaw ntawm cov roj, uas yog qhov sib xyaw ua ke ntawm hydrocarbons nrog me me ntawm oxygen, sulfur, nitrogen thiab lwm yam khoom.
Classic oxidizer -oxygen
Ib yam yooj yim lossis tshuaj lom neeg uas cov atoms txuas electrons hu ua oxidizing tus neeg sawv cev. Ib qho piv txwv classic ntawm cov khoom no yog oxygen, uas hloov mus ua oxides tom qab cov tshuaj tiv thaiv. Tab sis kuj yog tus neeg sawv cev oxidizing hauv cov tshuaj tiv thaiv redox yog ozone, uas txo qis rau cov organic tshuaj (piv txwv li, ketones thiab aldehydes), peroxides, hypochlorites, chlorates, nitric thiab sulfuric acids, manganese oxide thiab permanganate. Nws yooj yim pom tias tag nrho cov tshuaj no muaj oxygen.
Lwm yam oxidizers
Txawm li cas los xij, cov tshuaj tiv thaiv redox tsis yog tsuas yog cov txheej txheem cuam tshuam nrog oxygen. Hloov chaw, halogens, chromium, thiab txawm tias hlau cations thiab hydrogen ion (yog tias nws hloov mus ua ib yam khoom yooj yim raws li qhov tshwm sim ntawm cov tshuaj tiv thaiv) tuaj yeem ua tus neeg sawv cev oxidizing.
Ntau npaum li cas electrons yuav raug lees txais yog nyob ntawm qhov ntau ntawm cov oxidizing tus neeg sawv cev, nrog rau kev ua haujlwm ntawm cov hlau cuam tshuam nrog nws. Piv txwv li, nyob rau hauv cov tshuaj tiv thaiv ntawm concentrated nitric acid nrog ib tug hlau (zinc), 3 electrons tau txais, thiab nyob rau hauv kev sib cuam tshuam ntawm tib yam tshuaj, muab hais tias cov kua qaub nyob rau hauv ib tug heev dilute daim ntawv, twb 8 electrons.
Cov oxidizers muaj zog tshaj
Txhua tus neeg ua haujlwm oxidizing sib txawv ntawm lub zog ntawm lawv cov khoom. Yog li, hydrogen ion muaj peev xwm oxidizing tsawg, thaum atomic chlorine, tsim nyob rau hauv aqua regia (ib tug sib tov ntawm nitric thiab hydrochloric acids nyob rau hauv ib tug ratio ntawm 1: 3), muaj peev xwm oxidize txawm kub thiab platinum.
Concentrated selenic acid muaj cov khoom zoo sib xws. Qhov no ua rau nws tshwj xeeb ntawm lwm cov organic acids. Thaum diluted, nws tsis tuaj yeem cuam tshuam nrog kub, tab sis nws tseem muaj zog dua sulfuric acid, thiab tuaj yeem oxidize lwm cov kua qaub, xws li hydrochloric acid.
Ib qho piv txwv ntawm tus neeg sawv cev muaj zog oxidizing yog poov tshuaj permanganate. Nws ua tiav kev cuam tshuam nrog cov organic tebchaw thiab muaj peev xwm ua kom muaj zog carbon bonds. Copper oxide, cesium ozonide, cesium superoxide, nrog rau xenon difluoride, tetrafluoride thiab xenon hexafluoride kuj muaj kev ua haujlwm siab. Lawv lub peev xwm oxidizing yog vim muaj qhov muaj peev xwm electrode siab thaum hnov mob hauv cov tshuaj dilute aqueous.
Txawm li cas los xij, muaj cov tshuaj uas muaj peev xwm ntau dua. Ntawm cov inorganic molecules, fluorine yog cov muaj zog oxidizing tus neeg saib xyuas, tab sis nws tsis muaj peev xwm ua rau lub inert gas xenon tsis muaj cua sov thiab siab ntxiv. Tab sis qhov no tau ua tiav nrog platinum hexafluoride, difluorodioxide, krypton difluoride, nyiaj difluoride, divalent silver ntsev thiab lwm yam khoom. Rau lawv lub peev xwm tshwj xeeb rau redox cov tshuaj tiv thaiv, lawv tau muab cais ua oxidizers muaj zog heev.
Nyob zoo
Keeb kwm, lo lus "rov qab" yog ib qho piv txwv nrog deoxidation, uas yog, deprivation ntawm ib yam khoom ntawm oxygen. Txawm li cas los xij, dhau sij hawm, lo lus tau txais lub ntsiab lus tshiab, nws txhais tau tias kev rho tawm ntawm cov hlau los ntawm cov tebchaw uas muaj lawv, nrog rau cov tshuaj hloov pauv hauv cov tshuaj.cov electronegative ib feem ntawm cov khoom yog hloov los ntawm ib tug zoo nqi, xws li hydrogen.
Qhov nyuaj ntawm cov txheej txheem feem ntau nyob ntawm cov tshuaj affinity ntawm cov khoom nyob rau hauv lub compound. Qhov tsis muaj zog nws yog, qhov yooj yim dua cov tshuaj tiv thaiv yog nqa tawm. Feem ntau, cov affinity yog weaker nyob rau hauv endothermic compounds (kub yog absorbed thaum lawv tsim). Lawv txoj kev rov qab los yog yooj yim heev. Ib qho piv txwv zoo ntawm qhov no yog tawg.
Yuav kom muaj cov tshuaj tiv thaiv uas muaj cov khoom siv hluav taws xob (tsim nrog kev tso cua sov), lub zog muaj zog, xws li hluav taws xob tam sim no, yuav tsum tau siv.
qauv txo tus neeg sawv cev
Tus neeg saib xyuas thaum ub thiab feem ntau yog cov thee. Nws sib tov nrog ore oxides, thaum rhuab, oxygen tawm los ntawm qhov sib tov, uas ua ke nrog carbon. Qhov tshwm sim yog hmoov, granules lossis hlau alloy.
Lwm tus neeg txo qis yog hydrogen. Nws kuj tseem siv tau rau kuv cov hlau. Txhawm rau ua qhov no, cov oxides tau txhaws rau hauv lub raj uas dhau los ntawm cov kwj ntawm hydrogen. Yeej, txoj kev no yog siv rau tooj liab, txhuas, tin, nickel lossis cob alt. Koj tuaj yeem thov nws rau hlau, tab sis qhov txo qis yuav ua tsis tiav thiab dej tsim. Tib qhov teeb meem yog pom thaum sim kho zinc oxides nrog hydrogen, thiab nws yog ntxiv aggravated los ntawm volatility ntawm cov hlau. Potassium thiab lwm cov ntsiab lus tsis raug txo los ntawm hydrogen txhua.
Ntawm cov tshuaj tiv thaiv hauv organic chemistry
Kev nce qibQhov kev txo qis lees txais cov khoom siv hluav taws xob thiab yog li txo qis cov oxidation ntawm ib qho ntawm nws cov atoms. Txawm li cas los xij, nws yog qhov yooj yim los txiav txim siab qhov tseem ceeb ntawm cov tshuaj tiv thaiv los ntawm kev hloov oxidation lub xeev nrog kev koom tes ntawm inorganic tebchaw, thaum nyob rau hauv cov organic chemistry nws yog ib qho nyuaj rau xam cov oxidation tooj, nws feem ntau muaj ib tug fractional tus nqi.
txhawm rau taug qab cov tshuaj tiv thaiv redox uas muaj cov tshuaj organic, koj yuav tsum nco ntsoov cov cai hauv qab no: kev txo qis tshwm sim thaum lub tebchaw muab cov pa oxygen atoms thiab tau txais hydrogen atoms, thiab rov ua dua, oxidation yog qhov sib ntxiv ntawm oxygen.
Cov txheej txheem txo qis yog qhov tseem ceeb tshaj plaws rau kev siv tshuaj lom neeg. Nws yog nws leej twg underlies catalytic hydrogenation siv rau kev kuaj los yog kev lag luam lub hom phiaj, tshwj xeeb, kev ua kom huv ntawm cov tshuaj thiab tshuab los ntawm hydrocarbon thiab oxygen impurities.
Cov tshuaj tiv thaiv tuaj yeem ua rau ob qho tib si ntawm qhov kub thiab txias (txog 100 degrees Celsius thiab 1-4 atmospheres, ntsig txog), thiab kub siab (txog 400 degrees thiab ob peb puas cua). Kev tsim cov khoom siv organic yuav tsum tau siv cov cuab yeej nyuaj los muab cov xwm txheej zoo.
Active platinum pab pawg hlau lossis tsis muaj nuj nqis npib tsib xee, tooj liab, molybdenum thiab cob alt yog siv los ua catalysts. Qhov kev xaiv tom kawg yog kev lag luam ntau dua. Restoration tshwm sim los ntawm ib txhij sorption ntawm lub substrate thiab hydrogen nrog rau kev yooj yim ntawm cov tshuaj tiv thaiv ntawm lawv.
Kev txo qis cov tshuaj tiv thaiv txuas ntxiv musthiab hauv tib neeg lub cev. Qee qhov xwm txheej, lawv tuaj yeem muaj txiaj ntsig thiab tseem ceeb heev, hauv lwm tus lawv tuaj yeem ua rau muaj qhov tsis zoo. Piv txwv li, nitrogen-muaj cov tebchaw hauv lub cev tau hloov mus rau hauv thawj amines, uas, ntawm lwm cov haujlwm tseem ceeb, yog cov khoom siv protein uas yog cov khoom tsim ntawm cov ntaub so ntswg. Tib lub sijhawm, cov khoom noj aniline-dyed tsim cov tshuaj lom.
Yam kev tawm tsam
Yuav ua li cas cov tshuaj tiv thaiv redox, nws paub meej yog tias koj saib ntawm qhov muaj kev hloov pauv hauv oxidation xeev. Tab sis nyob rau hauv hom tshuaj hloov pauv no, muaj kev hloov pauv.
Yog li, yog tias cov molecules ntawm cov khoom sib txawv koom nrog hauv kev sib cuam tshuam, ib qho muaj xws li oxidizing atom, thiab lwm yam uas txo tus neeg sawv cev, cov tshuaj tiv thaiv yog suav tias yog intermolecular. Hauv qhov no, qhov sib npaug redox tuaj yeem ua raws li hauv qab no:
Fe + 2HCl=FeCl2 + H2.
Qhov sib npaug qhia tau tias oxidation xeev ntawm hlau thiab hydrogen hloov, thaum lawv yog ib feem ntawm cov khoom sib txawv.
Tab sis kuj tseem muaj cov tshuaj tiv thaiv intramolecular redox, uas ib qho atom hauv cov tshuaj oxidized thiab lwm qhov txo qis, thiab cov tshuaj tshiab tau txais:
2H2O=2H2 + O2.
Cov txheej txheem nyuaj dua tshwm sim thaum tib lub ntsiab lus ua raws li cov khoom siv hluav taws xob thiab cov neeg txais thiab tsim ntau lub tebchaw tshiab, uas suav nrog hauv cov xeev oxidation sib txawv. Cov txheej txheem zoo li no hu uadismutation los yog disproportionation. Ib qho piv txwv ntawm qhov no yog qhov hloov pauv hauv qab no:
4KClO3=KCl + 3KClO4.
Los ntawm qhov sib npaug saum toj no ntawm cov tshuaj tiv thaiv redox, nws tuaj yeem pom tau tias Bertolet ntsev, uas cov tshuaj chlorine nyob rau hauv lub xeev oxidation ntawm +5, decomposes rau hauv ob yam - poov tshuaj chloride nrog lub xeev oxidation ntawm chlorine -1 thiab perchlorate nrog tus lej oxidation ntawm +7. Nws hloov tawm tias tib lub caij ib txhij nce thiab txo nws cov oxidation xeev.
Kev thim rov qab ntawm cov txheej txheem ntawm kev sib hloov yog cov tshuaj tiv thaiv ntawm kev sib koom ua ke lossis rov ua dua. Nyob rau hauv nws, ob lub tebchaw, uas muaj tib lub ntsiab lus nyob rau hauv sib txawv oxidation xeev, react nrog ib leeg los tsim ib tug tshiab tshuaj nrog ib tug oxidation tooj:
SO2 +2H2S=3S + 2H2O.
Raws li koj tuaj yeem pom los ntawm cov piv txwv saum toj no, hauv qee qhov sib npaug, cov khoom yog ua ntej los ntawm cov lej. Lawv qhia cov naj npawb ntawm cov molecules koom nrog hauv cov txheej txheem thiab hu ua stoichiometric coefficients ntawm cov tshuaj tiv thaiv redox. Yuav kom qhov sib npaug kom raug, koj yuav tsum paub yuav ua li cas npaj lawv.
E-balance method
Qhov sib npaug hauv cov tshuaj tiv thaiv redox yog ib txwm khaws cia. Qhov no txhais tau hais tias tus neeg sawv cev oxidizing lees txais raws nraim li ntau cov electrons raws li tau muab los ntawm tus neeg ua kom txo qis. Yuav kom tsim tau ib qho kev sib npaug rau cov tshuaj tiv thaiv redox, koj yuav tsum ua raws li cov txheej txheem no:
- Kev txiav txim siab oxidation xeev ntawm cov khoom ua ntej thiab tom qab cov tshuaj tiv thaiv. Piv txwv li, hauvCov tshuaj tiv thaiv ntawm nitric acid thiab phosphorus nyob rau hauv lub xub ntiag ntawm dej tsim phosphoric acid thiab nitric oxide: HNO3 + P + H2O=H3PO4+ NO. Hydrogen nyob rau hauv tag nrho cov tebchaw muaj oxidation lub xeev ntawm +1, thiab oxygen muaj -2. Rau nitrogen, ua ntej pib cov tshuaj tiv thaiv, tus lej oxidation yog +5, thiab tom qab nws nce +2, rau phosphorus - 0 thiab +5, feem.
- Kos cov ntsiab lus uas tus lej oxidation tau hloov pauv (nitrogen thiab phosphorus).
- Compose electronic equations: N+5 + 3e=N+2; R0 - 5e=R+5.
- Sib npaug cov naj npawb ntawm cov hluav taws xob tau txais los ntawm kev xaiv qhov tsawg tshaj plaws ntau yam thiab suav cov lej sib npaug (tus lej 3 thiab 5 yog cov sib faib rau tus lej 15, raws li tus lej sib npaug rau nitrogen yog 5, thiab rau phosphorus 3): 5N +5 + (3 x 5)e=5N+2; 3P0 - 15e=3P+5.
- Ntxiv qhov tshwm sim ib nrab qhov tshwm sim raws li sab laug thiab sab xis: 5N+5 + 3P0=5N + 2 - 15th=3Р+5. Yog tias txhua yam ua tiav nyob rau theem no, cov hluav taws xob yuav poob qis.
- Rewrite the equation tag, tso down the coefficients as the electronic balance of the redox reaction: 5HNO3 + 3P + H2 O=3H 3PO4 + 5NO.
- Kuaj seb tus naj npawb ntawm cov ntsiab lus ua ntej thiab tom qab cov tshuaj tiv thaiv tseem zoo li qub nyob txhua qhov chaw, thiab yog tias tsim nyog, ntxiv coefficients nyob rau hauv pem hauv ntej ntawm lwm yam tshuaj (hauv qhov piv txwv no, tus nqi ntawm hydrogen thiab oxygen tsis sib npaug, thiaj li rau cov tshuaj tiv thaiv kab zauv kom zoo, koj yuav tsum tau ntxiv ib coefficient nyob rau hauv pem hauv ntej ntawmdej): 5HNO3+ 3P + 2H2O=3H3PO 4 + 5NO.
Txoj kev yooj yim no tso cai rau koj tso cov coefficients kom raug thiab zam kev tsis meej pem.
Piv txwv ntawm cov tshuaj tiv thaiv
Ib qho piv txwv ntawm cov tshuaj tiv thaiv redox yog kev cuam tshuam ntawm manganese nrog cov concentrated sulfuric acid, ua raws li hauv qab no:
Mn + 2H2SO4=MnSO4 + SO 2 + 2 H2O.
Cov tshuaj tiv thaiv redox pib nrog kev hloov pauv hauv oxidation xeev ntawm manganese thiab sulfur. Ua ntej pib ntawm cov txheej txheem, manganese nyob rau hauv lub xeev unbound thiab muaj xoom oxidation xeev. Tab sis thaum cuam tshuam nrog sulfur, uas yog ib feem ntawm cov kua qaub, nws nce oxidation xeev mus rau +2, yog li ua raws li ib tug electron pub. Sulfur, ntawm qhov tsis sib xws, ua lub luag haujlwm ntawm tus neeg txais, txo qis lub xeev oxidation ntawm +6 txog +4.
Txawm li cas los xij, tseem muaj cov tshuaj tiv thaiv uas manganese ua raws li cov khoom siv hluav taws xob. Piv txwv li, qhov no yog kev sib cuam tshuam ntawm nws cov oxide nrog hydrochloric acid, ua raws li cov tshuaj tiv thaiv:
MnO2+4HCL=MnCl2+Cl2+2 H2O.
Cov tshuaj tiv thaiv redox nyob rau hauv cov ntaub ntawv no pib nrog kev txo qis hauv oxidation xeev ntawm manganese los ntawm +4 txog +2 thiab nce oxidation xeev ntawm chlorine los ntawm -1 txog 0.
Yav dhau los, oxidation ntawm sulfur oxide nrog nitrogen oxide nyob rau hauv lub xub ntiag ntawm dej, uas ua rau 75% sulfuric acid, yog ib qho tseem ceeb tswv yim:
SO2 + NO2 + H2O=NO + H2So4.
Cov tshuaj tiv thaiv redox siv los ua hauv cov yees tshwj xeeb, thiab cov khoom kawg tau hu ua pej thuam. Tam sim no txoj kev no yog nyob deb ntawm tib qho kev tsim cov kua qaub, vim muaj lwm txoj hauv kev niaj hnub no, piv txwv li, kev sib cuag nrog cov khoom siv catalysts. Tab sis tau txais cov kua qaub los ntawm cov tshuaj tiv thaiv redox tsis yog tsuas yog kev lag luam xwb, tab sis kuj tseem ceeb hauv keeb kwm, txij li nws tau ua raws li cov txheej txheem uas tshwm sim nyob rau hauv huab cua ntawm London thaum Lub Kaum Ob Hlis 1952.
Cov tshuaj tiv thaiv kab mob kis tau ua rau huab cua txias txawv txawv, thiab cov neeg hauv nroog tau pib siv cov thee ntau los ua kom sov lawv lub tsev. Txij li thaum cov peev txheej no tsis zoo tom qab ua tsov ua rog, ntau cov sulfur dioxide tau nyob hauv huab cua, uas cuam tshuam nrog noo noo thiab nitrogen oxide nyob rau hauv qhov chaw. Raws li qhov tshwm sim ntawm qhov tshwm sim no, kev tuag ntawm cov me nyuam mos, cov neeg laus thiab cov neeg raug mob los ntawm cov kab mob ua pa tau nce. Qhov kev tshwm sim tau muab lub npe ntawm lub Great Smog.
Yog li, cov tshuaj tiv thaiv redox yog qhov tseem ceeb tshaj plaws. Kev nkag siab txog lawv cov txheej txheem tso cai rau koj kom nkag siab zoo txog cov txheej txheem ntuj tsim thiab ua tiav cov tshuaj tshiab hauv chav kuaj.
