Piv txwv ntawm Brønsted-Lowry Acid-Base Discussion Questions
Cov kua qaub thiab cov hauv paus yog cov tswv yim tseem ceeb hauv kev tshuaj lom neeg uas tau tsim thiab kho los ntawm ntau tus kws tshawb fawb tau ntau xyoo. Ib qho ntawm cov tswv yim nrov tshaj plaws yog Brønsted-Lowry txoj kev xav, uas tau tsim los ntawm Johannes Nicolaus Brønsted thiab Thomas Martin Lowry hauv xyoo 1923. Txoj kev xav no muab kev pom dav dua ntawm seb cov kua qaub thiab cov hauv paus sib cuam tshuam li cas hauv cov tshuaj lom neeg. Hauv tsab xov xwm no, peb yuav tham txog ntau qhov piv txwv ntawm cov teeb meem cuam tshuam nrog Brønsted-Lowry lub tswv yim ntawm cov kua qaub thiab cov hauv paus thiab yuav daws lawv li cas.
Cov Ntsiab Lus Tseem Ceeb ntawm Brønsted-Lowry Acids thiab Bases
Raws li Brønsted-Lowry txoj kev xav, cov kua qaub yog cov khoom uas tuaj yeem pub proton (H+), thaum cov hauv paus yog cov khoom uas tuaj yeem txais proton. Hauv cov tshuaj lom neeg, cov kua qaub thiab cov hauv paus sib cuam tshuam los ntawm cov txheej txheem hloov proton, qhov twg ib qho tshuaj ua haujlwm ua kua qaub los ntawm kev tso tawm proton, thiab lwm qhov tshuaj ua haujlwm ua lub hauv paus los ntawm kev txais proton.
Piv txwv ntawm Cov Tshuaj Tiv Thaiv Acid-Base
Ib qho piv txwv ntawm kev sib xyaw yooj yim ntawm cov kua qaub thiab lub hauv paus raws li Brønsted-Lowry txoj kev xav yog qhov sib xyaw ntawm tooj liab (II) sulfate (H2SO4) thiab sodium hydroxide (NaOH):
\[ \text{H}_2\text{SO}_4 + \text{NaOH} \rightarrow \text{NaHSO}_4 + \text{H}_2\text{O} \]
Hauv qhov kev tshuaj tiv thaiv no, sulfuric acid (H2SO4) ua haujlwm zoo li Brønsted-Lowry acid vim nws pub proton (H+) rau lub hauv paus NaOH, uas lees txais proton.
Cov Lus Nug thiab Kev Sib Tham Piv Txwv
Lo Lus Nug 1: Txheeb Xyuas Cov Acids thiab Bases
Lo lus nug:
Txheeb xyuas cov kua qaub thiab cov hauv paus ntawm Brønsted-Lowry hauv cov kev tshuaj tiv thaiv nram qab no:
\[ \text{NH}_3 + \text{H}_2\text{O} \rightarrow \text{NH}_4^+ + \text{OH}^- \]
Kev Sib Tham:
Hauv qhov kev tshuaj tiv thaiv no, ammonia (NH3) thiab dej (H2O) yog cov tshuaj tiv thaiv, thaum ammonium ions (NH4+) thiab hydroxide ions (OH-) yog cov khoom. Cia peb saib seb qhov twg ua haujlwm ua kua qaub thiab qhov twg ua haujlwm ua lub hauv paus.
- NH3 ua haujlwm ua lub hauv paus vim nws txais cov protons (H+) los ntawm H2O los ua NH4+.
- H2O ua haujlwm zoo li cov kua qaub vim nws pub cov proton (H+) rau NH3 los tsim OH-.
Yog li, nyob rau hauv qhov kev tshuaj tiv thaiv no:
– NH3 yog lub hauv paus Brønsted-Lowry.
– H2O yog Brønsted-Lowry acid.
Lo lus nug 2: Kev sau cov lus teb sib txuas
Lo lus nug:
Sau cov conjugate acid-base pairs rau cov tshuaj tiv thaiv hauv qab no:
\[ \text{HCl} + \text{H}_2\text{O} \rightarrow \text{H}_3\text{O}^+ + \text{Cl}^- \]
Kev Sib Tham:
Hauv qhov kev tshuaj tiv thaiv no, HCl ua haujlwm ua Brønsted-Lowry acid los ntawm kev pub proton (H+) rau H2O. Dej (H2O) txais proton thiab ua haujlwm ua Brønsted-Lowry base. Tom qab poob proton, HCl hloov mus ua Cl-, thiab H2O, tom qab tau txais proton, hloov mus ua H3O+.
- Acid (HCl) thiab nws cov conjugate puag (Cl-)
- Lub hauv paus (H2O) thiab nws cov kua qaub sib xyaw (H3O+)
Yog li, cov kua qaub-base sib xyaw ua ke hauv cov tshuaj tiv thaiv no yog:
– HCl / Cl-
– H2O / H3O+
Lo Lus Nug 3: Xam pH ntawm Cov Tshuaj Acid Tsis Muaj Zog
Lo lus nug:
Xam cov pH ntawm 0.1 M kua ntawm acetic acid (CH3COOH) yog tias nws paub tias qhov kev sib cais ntawm cov kua qaub (Ka) yog \(1.8 \times 10^{-5}\).
Kev Sib Tham:
Acetic acid yog ib qho kua qaub tsis muaj zog, thiab hauv dej nws tsuas yog ib feem ionizes raws li cov qauv hauv qab no:
\[ \text{CH}_3\text{COOH} \rightleftharpoons \text{CH}_3\text{COO}^- + \text{H}^+ \]
Cov kauj ruam los xam pH yog raws li nram no:
1. Teeb tsa qhov kev sib npaug ntawm kev siv qhov concentration pib thiab qhov kev hloov pauv ntawm qhov concentration:
\[ \text{Ka} = \frac{[\text{CH}_3\text{COO}^-][\text{H}^+]}{[\text{CH}_3\text{COOH}]} \]
2. Hloov cov nqi paub thiab daws rau \([H^+]\):
\[ 1.8 \times 10^{-5} = \frac{x^2}{0.1 – x} \]
Vim tias \(x\) me heev piv rau 0.1, peb tuaj yeem kwv yees \(0.1 – x \approx 0.1\):
\[ 1.8 \times 10^{-5} = \frac{x^2}{0.1} \]
\[ x^2 = 1.8 \times 10^{-6} \]
\[ x = \sqrt{1.8 \times 10^{-6}} \]
\[ x \kwv yees li 1.34 \times 10^{-3} \]
3. Xam tus pH:
\[ \text{pH} = -\log[ \text{H}^+] \]
\[ \text{pH} = -\log(1.34 \times 10^{-3}) \]
\[ \text{pH} \kwv yees li 2.87 \]
Yog li, pH ntawm 0.1 M acetic acid kua yog li 2.87.
Lo Lus Nug 4: Txheeb Xyuas Cov Kev Daws Teeb Meem Amphiprotic
Lo lus nug:
Txheeb xyuas cov tshuaj amphiprotic hauv cov tshuaj tiv thaiv hauv qab no thiab piav qhia vim li cas:
\[ \text{HCO}_3^- + \text{H}_2\text{O} \rightleftharpoons \text{H}_2\text{CO}_3 + \text{OH}^- \]
Kev Sib Tham:
Ib qho tshuaj amphiprotic yog ib qho tshuaj uas ua haujlwm tau zoo li kua qaub lossis kua qaub, nyob ntawm seb cov xwm txheej ntawm kev ua tshuaj. Hauv piv txwv ntawm kev ua tshuaj saum toj no:
- \(\text{HCO}_3^-\) ua haujlwm ua lub hauv paus thaum nws txais cov proton los ntawm \(\text{H}_2\text{O}\), tsim cov \(\text{H}_2\text{CO}_3\).
- \(\text{HCO}_3^-\) kuj tseem tuaj yeem ua haujlwm ua cov kua qaub nyob rau hauv lwm yam mob, tso tawm cov proton thiab tsim cov \(\text{CO}_3^{2-\).
Qhov no qhia tau hais tias cov ion \(\text{HCO}_3^-\) yog amphiprotic. Nws tuaj yeem ua haujlwm ua ob qho tib si acid (proton donor) thiab base (proton acceptor), nyob ntawm lwm yam khoom uas nws cuam tshuam nrog.
Nrog cov teeb meem piv txwv no, peb tuaj yeem nkag siab zoo dua txog kev siv Brønsted-Lowry acid-base theory los tshuaj xyuas thiab kwv yees kev sib cuam tshuam ntawm cov tshuaj. Kev nkag siab zoo txog txoj kev xav no yog lub hauv paus rau ntau daim ntawv thov hauv chemistry, biochemistry, thiab lwm yam kev tshawb fawb.
