Lub zog acid-base thiab pH
Cov kua qaub thiab cov hauv paus yog ob lub tswv yim tseem ceeb hauv chemistry uas ua lub luag haujlwm tseem ceeb hauv ntau yam tshuaj lom neeg thiab cov txheej txheem hauv lub neej. Kev nkag siab txog lub zog ntawm cov kua qaub thiab cov hauv paus, nrog rau lawv qhov kev ntsuas, yog qhov tseem ceeb hauv cov ntsiab lus hauv chav kuaj thiab hauv kev siv txhua hnub. Tsab xov xwm no yuav tshawb nrhiav lub zog ntawm cov kua qaub thiab cov hauv paus, lub tswv yim ntawm pH, thiab lawv cuam tshuam li cas thiab siv li cas.
Kev Txhais ntawm Acids thiab Bases
Hauv cov lus yooj yim, cov kua qaub yog ib yam khoom uas muaj peev xwm pub cov hydrogen ions (H⁺) hauv cov kua, thaum lub hauv paus yog ib yam khoom uas muaj peev xwm txais cov hydrogen ions no. Cov lus txhais no yog raws li Bronsted-Lowry txoj kev xav. Xwb, raws li Arrhenius txoj kev xav, cov kua qaub yog ib yam khoom uas tsim cov hydronium ions (H₃O⁺) hauv dej, thiab lub hauv paus yog ib yam khoom uas tsim cov hydroxide ions (OH⁻) hauv dej.
Lub zog ntawm cov kua qaub thiab cov hauv paus
Lub zog acid
Lub zog ntawm cov kua qaub yog hais txog nws lub peev xwm los tso cov hydrogen ions (H⁺) rau hauv cov kua. Cov kua qaub muaj zog yuav luag dissociate tag nrho hauv dej, txhais tau tias yuav luag tag nrho cov molecule kua qaub tso H⁺. Piv txwv ntawm cov kua qaub muaj zog yog hydrochloric acid (HCl), sulfuric acid (H₂SO₄), thiab nitric acid (HNO₃).
Nyob rau hauv kev sib piv, cov kua qaub tsis muaj zog tsuas yog ib feem ntawm kev sib cais hauv cov kua. Piv txwv ntawm cov kua qaub tsis muaj zog suav nrog acetic acid (CH₃COOH) thiab carbonic acid (H₂CO₃). Qib ntawm kev sib cais ntawm cov kua qaub tsis muaj zog feem ntau yog qhia los ntawm cov kua qaub sib cais tas li (Ka).
Lub zog pib
Ib yam li cov kua qaub, cov bases muaj peev xwm muab faib ua cov bases muaj zog lossis cov bases tsis muaj zog. Cov bases muaj zog yog cov uas yuav luag tag nrho ionize hauv cov kua. Piv txwv ntawm cov bases muaj zog suav nrog sodium hydroxide (NaOH) thiab potassium hydroxide (KOH).
Cov hauv paus tsis muaj zog, ntawm qhov tod tes, tsuas yog ib feem ionize hauv cov kua. Piv txwv ntawm cov hauv paus tsis muaj zog suav nrog ammonia (NH₃). Lub zog ntawm lub hauv paus kuj tseem ntsuas raws li qhov kev sib cais ntawm lub hauv paus (Kb).
Lub tswv yim pH
pH yog ib qho kev ntsuas ntawm acidity lossis alkalinity ntawm cov tshuaj. Nws yog ib qho logarithmic scale uas pib ntawm 0 txog 14. Qhov scale no yog txhais li:
\[
\text{pH} = -\log[H⁺]
\]
Qhov twg [H⁺] yog qhov concentration ntawm cov hydrogen ions hauv cov kua. pH ntawm 7 suav tias yog nruab nrab (zoo li dej ntshiab), pH hauv qab 7 yog acidic, thiab pH saum 7 yog basic.
Kev sib raug zoo ntawm Lub Zog thiab pH
Lub zog ntawm cov kua qaub lossis cov hauv paus muaj feem cuam tshuam rau pH ntawm cov tshuaj. Rau cov kua qaub muaj zog, vim tias lawv sib cais tag nrho, pH tuaj yeem suav ncaj qha los ntawm lawv cov molar concentration. Piv txwv li, cov tshuaj HCl 0.1 M muaj pH ntawm:
\[
\text{pH} = -\log[0.1] = 1
\]
Rau cov kua qaub tsis muaj zog, qib kev sib cais tsis tiav, yog li pH tsis tuaj yeem suav ncaj qha los ntawm qhov concentration molar pib. Hloov chaw, peb siv cov kab zauv Ka los txiav txim siab qhov concentration hydrogen ion ntawm qhov sib npaug.
Piv txwv li: Rau acetic acid (CH₃COOH) nrog Ka = 1.8 x 10⁻⁵, peb tuaj yeem xam pH ntawm 0.1 M kua siv cov qauv:
\[
Ka = \frac{[H⁺][A⁻]}{[HA]}
\]
Xav tias [H⁺] thiab [A⁻] yog x thiab [HA] ≈ 0.1 – x. Los ntawm no, daws rau x uas yog [H⁺], thiab tom qab ntawd xam pH.
Cov Ntawv Thov Hauv Lub Neej Txhua Hnub
Kev nkag siab txog lub zog ntawm cov kua qaub thiab cov hauv paus thiab pH muaj ntau yam kev siv hauv lub neej txhua hnub:
1. Kev Lag Luam Khoom Noj thiab Dej Haus
pH ua lub luag haujlwm tseem ceeb hauv kev ua zaub mov thiab dej haus. Piv txwv li, pH kom zoo yog qhov tsim nyog rau kev ua kom npias thiab cawv txiv hmab fermentation. Nws kuj tseem siv los tswj qhov zoo thiab kev nyab xeeb ntawm cov khoom noj.
2. Kev Noj Qab Haus Huv thiab Lub Cev Sib Npaug
Lub cev tib neeg xav tau pH ruaj khov thoob plaws nws cov kab ke. Piv txwv li, cov ntshav tib neeg muaj pH li ntawm 7.4. Kev hloov me me ntawm pH ntshav tuaj yeem ua rau muaj teeb meem kev noj qab haus huv loj.
3. Kev Ua Liaj Ua Teb
Av uas muaj pH kom raug yog qhov tseem ceeb rau kev ua liaj ua teb kom zoo. pH ntawm av cuam tshuam rau kev muaj cov as-ham rau cov nroj tsuag. Yog li ntawd, cov neeg ua liaj ua teb feem ntau kho pH ntawm av los ntawm kev ntxiv cov txiv qaub kom nce lossis ntxiv cov sulfur kom txo qis.
4. Kev Kho Dej
pH ntawm dej yog ib qho cim qhia tseem ceeb ntawm qhov zoo ntawm dej. Kev tswj hwm pH ntawm dej tuaj yeem cuam tshuam rau ntau yam, suav nrog saj, xim, thiab kev tua kab mob. Cov kua qaub lossis cov hauv paus feem ntau raug ntxiv rau hauv dej kom ua tiav pH xav tau thaum lub sijhawm kho dej.
5. Kev Tswj Xyuas Kev Ua Phem
Cov lag luam feem ntau saib xyuas pH ntawm lawv cov dej khib nyiab kom ua tau raws li cov qauv ib puag ncig thiab txo cov pa phem. Ua ntej cov dej khib nyiab raug tso tawm mus rau hauv ib puag ncig, nws feem ntau raug tshem tawm los ntawm kev ntxiv cov kua qaub lossis cov hauv paus kom coj cov pH ze rau qhov nruab nrab.
Cov Yam Cuam Tshuam Rau Lub Zog Ntawm Cov Acids Thiab Bases
Muaj ntau yam uas cuam tshuam rau lub zog ntawm cov kua qaub thiab cov hauv paus, uas yog:
1. Cov Qauv Molecular
Cov qauv molecular ua lub luag haujlwm tseem ceeb hauv kev txiav txim siab lub zog ntawm cov kua qaub lossis cov hauv paus. Cov kua qaub uas muaj cov kev sib txuas zoo ntawm cov hydrogen atoms thiab cov atom sib txuas feem ntau tsis muaj zog vim lawv muaj teeb meem tso tawm cov hydrogen ions. Ntawm qhov tod tes, cov kua qaub uas muaj cov kev sib txuas tsis muaj zog feem ntau muaj zog.
2. Kev sib nqus hluav taws xob
Qhov electronegativity ntawm cov atoms sib txuas lus muaj feem cuam tshuam zoo rau lub zog ntawm cov kua qaub. Cov atoms uas muaj electronegativities siab feem ntau nyiam ntau cov electrons, ua rau nws yooj yim dua rau lawv tso tawm cov hydrogen ions.
3. Cov kuab tshuaj
Cov tshuaj yaj kuj cuam tshuam rau lub zog ntawm cov kua qaub thiab cov hauv paus. Piv txwv li, dej yog cov tshuaj yaj zoo heev rau cov kua qaub thiab cov hauv paus vim nws muaj polarity siab.
4. Cov nyhuv inductive
Qhov cuam tshuam ntawm cov pab pawg atomic sib txawv hauv ib lub molecule kuj cuam tshuam rau nws lub zog. Cov pab pawg electron-withdrawn (xws li halogens) hauv ib lub molecule feem ntau ua rau acidity nce ntxiv.
Xaus
Kev paub txog cov kua qaub thiab cov hauv paus, suav nrog lawv lub zog thiab pH, yog qhov tseem ceeb rau kev nkag siab txog ntau yam tshuaj lom neeg thiab kev siv hauv ntau qhov chaw. Lub zog ntawm cov kua qaub thiab cov hauv paus yog txiav txim siab los ntawm lawv lub peev xwm los tso tawm lossis txais cov hydrogen ions, uas cuam tshuam ncaj qha rau pH ntawm cov tshuaj. Kev nkag siab txog kev paub no tsis yog tsuas yog pab tau hauv kev tshawb fawb xwb tab sis kuj tseem muaj nyob rau hauv lub neej txhua hnub thiab ntau yam lag luam. Kev nkag siab no ua rau muaj kev siv dav dua thiab pab txhawb kev siv cov txheej txheem tsim nyog hauv ntau yam txheej txheem, los ntawm kev lag luam zaub mov mus rau kev kho dej thiab kev kho mob. Yog li ntawd, kev paub txog nws yog qhov tseem ceeb rau kev nce qib hauv kev siv tshuab thiab txhim kho lub neej zoo.
