Mienzaniso yeMibvunzo neKukurukurirana kweWeak Acids neWeak Bases
Pendauluan
Asidhi nemabhesi ipfungwa mbiri huru mukemistri dzakakosha kunzwisisa. Asidhi asina simba nemabhesi asina simba anoita basa rakakosha mukuita kwakasiyana-siyana kwemakemikari, murabhoritari uye muhupenyu hwezuva nezuva. Chinyorwa chino chichataura nezvematambudziko emuenzaniso uye hurukuro yakadzama yeasidhi asina simba nemabhesi asina simba.
Kunzwisisa Asidhi Asina Simba uye Zvigadziko Zvisina Simba
Asidhi Isina Simba
Asidhi isina simba iasidhi isingaparadzanise zvachose mumushonga wemvura. Izvi zvinoreva kuti mumushonga weasidhi isina simba, chikamu chidiki chete chemamorekuru easidhi chinopatsanurwa kuita maion ehydrogen (\(\text{H}^+\)) uye conjugate anion (\(\text{A}^-\)). Muenzaniso wakajairika weasidhi isina simba iacetic acid (\(\text{CH}_3\text{COOH}\)).
Nzvimbo Isina Simba
Hwaro husina kusimba ihwaro husingaparadzanise zvachose mumushonga wemvura. Hwaro husina kusimba hunongopatsanurwa zvishoma kuita ma hydroxide ions (\(\text{OH}^-\)) uye conjugate cations. Muenzaniso wakajairika wehwaro husina kusimba iammonia (\(\text{NH}_3\)).
Mafomura Emakemikari Ekutanga eAcids Asidhi uye Zvigadziko Zvisina Simba
Asidhi Isina Simba
Kuparadzaniswa kweasidhi isina simba mumvura kunogona kuratidzwa ne equation inotevera:
\[
\text{HA} \rightleftharpoons \text{H}^+ + \text{A}^-
\]
ne \(\text{HA}\) seasidhi isina simba uye \(\text{A}^-\) seanion inosanganiswa.
Chinogarochinjana cheacid (\(K_a\)) chinoshandiswa kutsanangura simba reasidhi isina simba:
\[
K_a = \frac{[\text{H}^+][\text{A}^-]}{[\text{HA}]}
\]
Nzvimbo Isina Simba
Kuparadzaniswa kwehwaro husina simba mumvura kunogona kuratidzwa seizvi:
\[
\text{B} + \text{H}_2\text{O} \rightleftharpoons \text{BH}^+ + \text{OH}^-
\]
ne \(\text{B}\) sehwaro husina kusimba uye \(\text{BH}^+\) se conjugate cation.
Chinongedzo che "base dissociation constant" (\(K_b\)) chinoshandiswa kutsanangura simba re "weak base":
\[
K_b = \frac{[\text{BH}^+][\text{OH}^-]}{[\text{B}]}
\]
Mibvunzo yemuenzaniso nekukurukurirana
Muenzaniso Mubvunzo 1: Asidhi Isina Simba
Mubvunzo: Verenga pH ye 0.1 M solution ye acetic acid (\(\text{CH}_3\text{COOH}\)) kana \(K_a\) ye acetic acid iri \(1.8 \times 10^{-5}\).
Kukurukurirana:
1. Nyora equation yekuparadzanisa:
\[
\text{CH}_3\text{COOH} \rightleftharpoons \text{CH}_3\text{COO}^- + \text{H}^+
\]
2. Sarudza huwandu hwekutanga uye shanduko muhuwandu hwehuwandu mu ICE (yekutanga, shanduko, kuenzana).
| | \(\text{CH}_3\text{COOH}\) | \(\text{CH}_3\text{COO}^-\) | \(\text{H}^+\) |
|——-|—————————--|———————-|——————–|
| Chekutanga | 0.1 M | 0 | 0 |
| Shanduko | -x | +x | +x |
| Kuenzana | 0.1 – x | x | x |
3. Batanidza \(K_a\) nehuwandu hwezvinhu pakuenzanisa:
\[
K_a = \frac{[H^+][CH_3COO^-]}{[CH_3COOH]} = \frac{x \cdot x}{0.1 – x}
\]
Sezvo \(K_a\) iri diki, fungidziro \(x \ll 0.1\) inowanzo shanda:
\[
K_a \approx \frac{x^2}{0.1}
\]
\[
1.8 \kawa 10^{-5} = \frac{x^2}{0.1}
\]
\[
x^2 = 1.8 \kawa 10^{-6}
\]
\[
x = 1.34 \kawa 10^{-3}
\]
4. Verenga pH:
\[
\text{pH} = -\log[H^+] = -\log(1.34 \times 10^{-3}) = 2.87
\]
Muenzaniso Mubvunzo 2: Zvigadziko Zvisina Simba
Mubvunzo: Verenga pOH ye 0.05 M ammonia solution (\(\text{NH}_3\)) kana \(K_b\) yeammonia iri \(1.8 \times 10^{-5}\).
Kukurukurirana:
1. Nyora equation yekuparadzanisa:
\[
\text{NH}_3 + \text{H}_2\text{O} \rightleftharpoons \text{NH}_4^+ + \text{OH}^-
\]
2. Sarudza huwandu hwekutanga hwezvinhu uye shanduko yehuwandu hwezvinhu mu ICE table:
| | \(\text{NH}_3\) | \(\text{NH}_4^+\) | \(\text{OH}^-\) |
|——-|——————–|———————-|——————|
| Chekutanga | 0.05 M | 0 | 0 |
| Shanduko | -x | +x | +x |
| Kuenzana | 0.05 – x | x | x |
3. Batanidza \(K_b\) nehuwandu hwezvinhu pakuenzanisa:
\[
K_b = \frac{[\text{NH}_4^+][\text{OH}^-]}{[\text{NH}_3]} = \frac{x \cdot x}{0.05 – x}
\]
Kufungidzira \(x \ll 0.05\):
\[
K_b \approx \frac{x^2}{0.05}
\]
\[
1.8 \kawa 10^{-5} = \frac{x^2}{0.05}
\]
\[
x^2 = 9 \kawa 10^{-7}
\]
\[
x = 3 \kawa 10^{-4}
\]
4. Verenga pOH:
\[
\text{pOH} = -\log[OH^-] = -\log(3 \kawa 10^{-4}) = 3.52
\]
5. Shandura kuita pH kana zvichidikanwa:
\[
\text{pH} = 14 – \text{pOH} = 14 – 3.52 = 10.48
\]
Mhedziso
Kunzwisisa maasidhi asina simba uye mabhesi asina simba kuburikidza nematambudziko emuenzaniso kunobatsira zvikuru mukufanotaura maitiro avo emakemikari mumhinduro. Nekunzwisisa pfungwa dze \(K_a\) uye \(K_b\) uye maitiro ekushandura huwandu hweion kuita pH kana pOH, tinogona kuongorora mhinduro dzakasiyana-siyana mumamiriro ese edzidzo uye emaindasitiri. Ramba uchidzidzira nematambudziko akasiyana-siyana kuti unzwisise uye hunyanzvi hwako mukuongorora makemikari.
