Yuav Ua Li Cas Txheeb Xyuas Cov Naj Npawb Oxidation
Kev nkag siab txog cov lej oxidation (lossis cov xeev oxidation) yog ib lub tswv yim tseem ceeb hauv chemistry uas pab peb nkag siab txog cov tshuaj lom neeg, tshwj xeeb tshaj yog cov tshuaj redox. Tus lej oxidation yog tus lej ntawm cov electrons uas yuav tsum tau ntxiv lossis tshem tawm ntawm ib lub atom kom hloov nws mus rau nws lub xeev av. Hauv tsab xov xwm no, peb yuav tshawb nrhiav tob txog yuav ua li cas txiav txim siab tus lej oxidation ntawm ib qho khoom hauv cov tshuaj lom neeg.
Cov Ntsiab Lus Tseem Ceeb ntawm Oxidation Number
Cov lej oxidation tuaj yeem xav txog tias yog ib qho cuab yeej suav uas piav qhia txog kev faib tawm ntawm cov electrons hauv ib lub molecule lossis ion. Txawm hais tias cov lej oxidation tsis yog ib txwm sawv cev rau qhov them hluav taws xob tiag tiag ntawm cov atoms hauv lub molecule, lawv ua kom yooj yim rau cov txheej txheem ntawm kev tshuaj xyuas tshuaj.
Qee cov cai yooj yim rau kev txiav txim siab cov lej oxidation yog raws li nram no:
1. Tus lej oxidation ntawm ib yam khoom hauv daim ntawv ntawm ib yam khoom molecule (homonuclear) yeej ib txwm yog xoom. Piv txwv li:
– O₂ (dioxygen) -> Nws tus lej oxidation yog 0
– N₂ (dinitrogen) -> Nws tus lej oxidation yog 0
2. Tus lej oxidation rau ib qho ion monatomic yog sib npaug rau qhov them ntawm cov ion.
– Na⁺ -> Nws tus lej oxidation yog +1
– Cl⁻ -> Nws tus lej oxidation yog -1
3. Tus lej oxidation ntawm hydrogen yog +1 thaum nws raug sib txuas nrog cov hlau uas tsis yog hlau thiab -1 thaum nws raug sib txuas nrog cov hlau hauv hydride. Piv txwv li:
– H₂O -> Hydrogen muaj tus lej oxidation ntawm +1
– NaH -> Hydrogen muaj tus lej oxidation ntawm -1
4. Tus lej oxidation ntawm cov pa oxygen feem ntau yog -2 hauv feem ntau cov tshuaj sib xyaw, tab sis muaj qee qhov kev zam xws li hauv peroxides qhov twg tus lej oxidation ntawm cov pa oxygen yog -1.
– H₂O -> Cov pa oxygen muaj tus lej oxidation ntawm -2
– H₂O₂ (hydrogen peroxide) -> Cov pa oxygen muaj tus lej oxidation ntawm -1
5. Tus lej oxidation ntawm halogens (F, Cl, Br, I) hauv cov tshuaj feem ntau yog -1, tshwj tsis yog thaum sib xyaw nrog oxygen lossis lwm yam halogens uas nws tuaj yeem txawv.
Cov Kauj Ruam Los Txheeb Xyuas Cov Naj Npawb Oxidation
Yuav kom txiav txim siab tus lej oxidation ntawm ib qho khoom hauv ib qho compound, peb tuaj yeem ua raws li cov kauj ruam no:
Kauj Ruam 1: Sau Cov Qauv Molecular / Formula ntawm Cov Tshuaj
Pib los ntawm kev sau cov qauv molecular lossis cov mis ntawm cov tshuaj. Piv txwv li, rau H₂SO₄ (sulfuric acid).
Kauj Ruam 2: Txheeb Xyuas Tus Naj Npawb Oxidation ntawm Cov Khoom Raws Li Cov Cai
- Rau H₂SO₄, peb paub tias hydrogen yuav luag ib txwm muaj tus lej oxidation ntawm +1 thiab oxygen yuav luag ib txwm -2.
– Hydrogen (H): +1 (2 H atoms, +2 tag nrho)
– Cov pa oxygen (O): -2 (4 O atoms, -8 tag nrho)
Kauj Ruam 3: Txheeb Xyuas Tus lej Oxidation ntawm Cov Khoom Tsis Paub
Yog tias cov tshuaj sib xyaw yuav tsum tsis muaj zog kiag li lossis yog tias peb tab tom tsim cov ions, peb yuav tsum xyuas kom meej tias tus nqi tag nrho ntawm tus lej oxidation yog xoom rau cov tshuaj sib xyaw tsis muaj zog lossis sib npaug rau tus nqi ionic rau cov ions.
– Sulfuric acid (H₂SO₄) yog ib qho tshuaj tsis muaj zog. Yog li ntawd, tag nrho cov xeev oxidation yuav tsum yog xoom.
- Peb twb muaj cov lej oxidation rau H (+1) thiab O (-2), yog li nrhiav tus lej oxidation ntawm sulfur (S), peb siv cov qauv:
\[
2(+1) + S + 4(-2) = 0
\]
\[
2 + S – 8 = 0
\]
\[
S – 6 = 0
\]
\[
S = +6
\]
Yog li, tus lej oxidation rau sulfur hauv H₂SO₄ yog +6.
Kauj Ruam 4: Kev Txheeb Xyuas
Xyuas kom tseeb tias tag nrho cov lej oxidation yog sib npaug rau 0 rau cov molecules tsis muaj zog lossis sib raug rau cov nqi ionic yog tias peb ua haujlwm nrog ions.
Lwm Piv Txwv ntawm Kev Txheeb Xyuas Cov Naj Npawb Oxidation
Piv txwv 1: Potassium Permanganate (KMnO₄)
Rau qhov kev sib xyaw no peb ua raws li cov cai saum toj no:
- Potassium (K): Feem ntau +1
– Cov pa oxygen (O): -2
Peb paub tias lub molecule no yog nruab nrab, ua rau muaj qhov sib npaug:
\[
1(+1) + Mn + 4(-2) = 0
\]
\[
1 + Mn – 8 = 0
\]
\[
Mn – 7 = 0
\]
\[
Mn = +7
\]
Yog li, tus lej oxidation ntawm Mn hauv KMnO₄ yog +7.
Piv txwv 2: Ammonium Nitrate (NH₄NO₃)
Rau cov tshuaj no peb muaj ob ntu: NH₄⁺ thiab NO₃⁻.
– NH₄⁺:
- Hydrogen (H): +1
- Yog li rau nitrogen (N) hauv NH4:
\[
N + 4(+1) = +1
\]
\[
N + 4 = +1
\]
\[
N = -3
\]
– TSIS MUAJ₃⁻:
– Cov pa oxygen (O): -2
– Nitrogen (N) hauv NO₃⁻:
\[
N + 3(-2) = -1
\]
\[
N – 6 = -1
\]
\[
N = +5
\]
Qee Qhov Kev Zam thiab Cov Teeb Meem Tshwj Xeeb
Muaj qee qhov kev zam rau txoj cai dav dav uas yuav tsum nco ntsoov:
1. Cov pa oxygen hauv Peroxide:
- Hauv H₂O₂ lossis Na₂O₂, cov pa oxygen muaj tus lej oxidation ntawm -1, tsis yog -2.
2. Cov ntsiab lus uas muaj ntau tus lej Oxidation:
– Cov ntsiab lus xws li phosphorus (P), sulfur (S), thiab cov hlau hloov pauv feem ntau muaj cov lej oxidation sib txawv hauv cov sib xyaw sib txawv. Piv txwv li, hlau (Fe) tuaj yeem muaj tus lej oxidation ntawm +2 lossis +3.
3. Cov Hlau Alkaline Earth yeej ib txwm yog +2 thiab cov hlau Alkali yeej ib txwm yog +1.
Xaus
Kev txiav txim siab cov lej oxidation yog ib qho kev txawj tseem ceeb thiab tseem ceeb hauv chemistry, tshwj xeeb tshaj yog rau kev nkag siab txog cov tshuaj redox thiab ntau hom tshuaj lom neeg. Los ntawm kev ua raws li cov cai thiab cov kauj ruam saum toj no, koj yuav muaj peev xwm txiav txim siab cov lej oxidation hauv ntau yam tshuaj lom neeg. Xyaum txiav txim siab cov lej oxidation nrog ntau yam piv txwv ntawm cov tshuaj kom txhawb koj txoj kev nkag siab.
