Cov Lus Nug Piv Txwv Sib Tham Txog Lub Zog ntawm Cov Acids thiab Bases
Lub zog ntawm cov kua qaub thiab cov hauv paus yog cov ntsiab lus tseem ceeb hauv kev tshuaj lom neeg uas qhia tau tias cov kua qaub lossis cov hauv paus molecule tuaj yeem pub cov proton (H⁺) lossis txais cov proton tau zoo npaum li cas. Hauv kev sib tham no, peb yuav saib ob peb qhov teeb meem piv txwv uas yuav pab peb nkag siab txog lub zog ntawm cov kua qaub thiab cov hauv paus, nrog rau yuav ua li cas xam lawv cov pH thiab pOH. Ua ntej peb nkag mus rau hauv kev sib tham txog teeb meem, cia peb xub nkag siab txog cov hauv paus ntawm kev xav txog cov kua qaub thiab cov hauv paus.
Kev Taw Qhia Txog Lub Zog ntawm Cov Acids thiab Bases
Lub zog ntawm cov kua qaub los yog cov hauv paus tuaj yeem txiav txim siab los ntawm nws qib ionization hauv cov kua. Cov kua qaub muaj zog yog cov uas yuav luag tag nrho ionized hauv cov kua, thaum cov kua qaub tsis muaj zog tsuas yog ionized ib nrab. Tib yam no yog qhov tseeb rau cov hauv paus.
Cov Acids Muaj Zog thiab Cov Acids Tsis Muaj Zog
Cov kua qaub muaj zog, xws li:
- Hydrochloric acid (HCl)
- Cov kua qaub sulfuric (H₂SO₄)
- Nitric acid (HNO₃)
Nws yuav luag tag nrho cov ionized nyob rau hauv cov kua. Piv txwv li, HCl nyob rau hauv dej yuav dissociate mus rau hauv H⁺ thiab Cl⁻ yuav luag tag nrho.
Cov kua qaub tsis muaj zog, xws li:
- Acetic acid (CH₃COOH)
- Hydrofluoric acid (HF)
- Citric acid (C₆H₈O₇)
tsuas yog ib feem ionized hauv cov kua. Qhov no txhais tau tias txhua lub sijhawm, qee cov kua qaub tseem nyob hauv daim ntawv molecular thiab tsis dissociate ua ions.
Cov Hauv Paus Muaj Zog thiab Cov Hauv Paus Tsis Muaj Zog
Cov hauv paus muaj zog, xws li:
- Sodium hydroxide (NaOH)
- Potassium hydroxide (KOH)
- Calcium hydroxide (Ca(OH)₂)
Nws yuav luag tag nrho ionized nyob rau hauv cov kua dej, tsim tawm ntau ntawm OH⁻ ions.
Cov hauv paus tsis muaj zog, xws li:
- Ammonia (NH₃)
- Methylamine (CH₃NH₂)
nws tsuas yog ib feem ionizes hauv cov kua, tsim cov OH⁻ ions me me.
Cov Lus Nug Piv Txwv thiab Kev Sib Tham
Cia peb sim ua qee cov piv txwv teeb meem kom nkag siab zoo dua txog lub tswv yim no.
Piv txwv lus nug 1: Xam pH ntawm cov kua qaub muaj zog
Lo lus nug:
Xam cov pH ntawm cov kua HCl 0,1 M.
Kev Sib Tham:
HCl yog ib qho kua qaub muaj zog, yog li nws yuav ionize tag nrho hauv cov kua:
\[ \text{HCl} \rightarrow \text{H}^+ + \text{Cl}^- \]
Vim tias HCl yog ionized tag nrho, qhov concentration ntawm [H⁺] yog sib npaug rau qhov concentration ntawm HCl:
\[ [\text{H}^+] = 0,1 \, \text{M} \]
\[ \text{pH} = -\log[ \text{H}^+] \]
\[ \text{pH} = -\log(0,1) \]
\[ \text{pH} = 1 \]
Yog li, pH ntawm 0,1 M HCl kua yog 1.
Piv txwv lus nug 2: Xam tus pH ntawm cov kua qaub tsis muaj zog
Lo lus nug:
Xam tus pH ntawm cov kua 0,1 M CH₃COOH. Paub tias Ka (acid dissociation constant) ntawm CH₃COOH yog \(1,8 \times 10^{-5}\).
Kev Sib Tham:
Rau cov kua qaub tsis muaj zog, qib ntawm ionization yuav tsum tau coj mus rau hauv tus account. Cov qauv sib npaug rau kev sib cais ntawm acetic acid yog:
\[ \text{CH}_3\text{COOH} \rightleftharpoons \text{H}^+ + \text{CH}_3\text{COO}^- \]
Los ntawm kev siv Ka:
\[ \text{Ka} = \frac{[\text{H}^+][\text{CH}_3\text{COO}^-]}{[\text{CH}_3\text{COOH}]} \]
Xav tias qhov kev sib cais [H⁺] = [CH₃COO⁻] = x thiab thawj [CH₃COOH] yog 0,1 M, ces:
\[ 1,8 \times 10^{-5} = \frac{x^2}{0,1 – x} \]
Vim tias Ka me me, x tuaj yeem tsis quav ntsej piv rau 0,1:
\[ 1,8 \times 10^{-5} \approx \frac{x^2}{0,1} \]
\[ x^2 = 1,8 \times 10^{-6} \]
\[ x = \sqrt{1,8 \times 10^{-6}} \]
\[ x \kwv yees li 1,34 \times 10^{-3} \]
Ces, [H⁺] ≈ \(1,34 \times 10^{-3} \):
\[ \text{pH} = -\log[ \text{H}^+] \]
\[ \text{pH} = -\log(1,34 \times 10^{-3}) \]
\[ \text{pH} \kwv yees li 2,87 \]
Yog li, pH ntawm 0,1 M CH₃COOH kua yog li 2,87.
Piv txwv lus nug 3: Xam pOH thiab pH ntawm Cov Hauv Paus Muaj Zog
Lo lus nug:
Xam cov pOH thiab pH ntawm cov kua NaOH 0,01 M.
Kev Sib Tham:
NaOH yog lub hauv paus muaj zog uas tau ionized tag nrho hauv dej:
\[ \text{NaOH} \rightarrow \text{Na}^+ + \text{OH}^- \]
Vim tias NaOH yog ionized tag nrho, qhov concentration ntawm [OH⁻] yog sib npaug rau qhov concentration ntawm NaOH:
\[ [\text{OH}^-] = 0,01 \, \text{M} \]
\[ \text{pOH} = -\log[\text{OH}^-] \]
\[ \text{pOH} = -\log(0,01) \]
\[ \text{pOH} = 2 \]
Nws paub tias pH thiab pOH muaj feem cuam tshuam los ntawm kev sib npaug:
\[ \text{pH} + \text{pOH} = 14 \]
Yog li ntawd,
\[ \text{pH} = 14 – \text{pOH} \]
\[ \text{pH} = 14 – 2 \]
\[ \text{pH} = 12 \]
Yog li, pOH ntawm 0,01 M NaOH kua yog 2, thiab pH yog 12.
Piv txwv lus nug 4: Xam tus pH ntawm lub hauv paus tsis muaj zog
Lo lus nug:
Xam tus pH ntawm cov kua 0,1 M NH₃. Paub tias Kb (base dissociation constant) ntawm NH₃ yog \(1,76 \times 10^{-5}\).
Kev Sib Tham:
NH₃ hauv dej ua rau muaj NH₄⁺ thiab OH⁻:
\[ \text{NH}_3 + \text{H}_2\text{O} \rightleftharpoons \text{NH}_4^+ + \text{OH}^- \]
Los ntawm kev siv Kb,
\[ \text{Kb} = \frac{[\text{NH}_4^+][\text{OH}^-]}{[\text{NH}_3]} \]
Xav tias qhov kev sib cais [OH⁻] = [NH₄⁺] = x, thiab qhov pib [NH₃] yog 0,1 M, ces:
\[ 1,76 \times 10^{-5} = \frac{x^2}{0,1 – x} \]
Raws li kev xav, x yog me me piv rau 0,1:
\[ 1,76 \times 10^{-5} \approx \frac{x^2}{0,1} \]
\[ x^2 = 1,76 \times 10^{-6} \]
\[ x = \sqrt{1,76 \times 10^{-6}} \]
\[ x \kwv yees li 1,33 \times 10^{-3} \]
Ces, [OH⁻] ≈ \(1,33 \times 10^{-3}\):
\[ \text{pOH} = -\log[\text{OH}^-] \]
\[ \text{pOH} = -\log(1,33 \times 10^{-3}) \]
\[ \text{pOH} \kwv yees li 2,88 \]
Tom qab ntawd, pH yog xam los ntawm:
\[ \text{pH} = 14 – \text{pOH} \]
\[ \text{pH} = 14 – 2,88 \]
\[ \text{pH} \kwv yees li 11,12 \]
Yog li, pH ntawm 0,1 M NH₃ kua yog li 11,12.
Xaus
Kev nkag siab txog lub zog ntawm cov kua qaub thiab cov hauv paus yog qhov tseem ceeb rau kev tshuaj lom neeg. Los ntawm kev nkag siab txog yuav ua li cas xam pH thiab pOH, thiab paub yuav ua li cas txheeb xyuas cov kua qaub thiab cov hauv paus tsis muaj zog thiab muaj zog, koj yuav npaj tau zoo dua los daws ntau yam teeb meem tshuaj lom neeg uas cuam tshuam nrog kev daws teeb meem. Cov piv txwv uas tau muab los vam tias yuav ua kom meej cov ntsiab lus no thiab muab lub hauv paus ruaj khov rau kev kawm ntxiv.
