Mehlala ea Lipotso le Puisano ea Li-acid tse Fokolang le Metheo e Fokolang
Pendahuluan
Li-acid le metheo ke likhopolo tse peli tsa motheo k'hemistri tse bohlokoa ho li utloisisa. Li-acid tse fokolang le metheo e fokolang li bapala karolo ea bohlokoa liketsong tse fapaneng tsa lik'hemik'hale, libakeng tsa laboratori le bophelong ba letsatsi le letsatsi. Sengoloa sena se tla akaretsa mathata a mohlala le puisano e qaqileng ea li-acid tse fokolang le metheo e fokolang.
Ho Utloisisa Li-acid tse Fokolang le Metheo e Fokolang
Asiti e Fokolang
Asiti e fokolang ke asiti e sa arohaneng ka botlalo ka tharollong ea metsi. Sena se bolela hore ka tharollong ea asiti e fokolang, karolo e nyane feela ea limolek'hule tsa asiti e arohanang ho ba li-ion tsa hydrogen (\(\text{H}^+\)) le anion e kopaneng (\(\text{A}^-\)). Mohlala o tloaelehileng oa asiti e fokolang ke asiti ea acetic (\(\text{CH}_3\text{COOH}\)).
Motheo o Fokolang
Motheo o fokolang ke motheo o sa arohaneng ka ho feletseng ka tharollo ea metsi. Metheo e fokolang e arohana hanyane feela ho ba li-ion tsa hydroxide (\(\text{OH}^-\)) le li-cation tse kopaneng. Mohlala o tloaelehileng oa motheo o fokolang ke ammonia (\(\text{NH}_3\)).
Mekhoa ea motheo ea lik'hemik'hale bakeng sa li-acid tse fokolang le metheo e fokolang
Asiti e Fokolang
Karabelo ea ho arohana ha asiti e fokolang ka metsing e ka hlalosoa ka equation e latelang:
\[
\text{HA} \rightleftharpoons \text{H}^+ + \text{A}^-
\]
ka \(\text{HA}\) e le asiti e fokolang le \(\text{A}^-\) e le anion e kopaneng.
Sephetho sa ho arohana ha asiti (\(K_a\)) se sebelisetsoa ho hlalosa matla a asiti e fokolang:
\[
K_a = \frac{[\text{H}^+][\text{A}^-]}{[\text{HA}]}
\]
Motheo o Fokolang
Karabelo ea karohano ea motheo o fokolang ka metsing e ka hlalosoa ka tsela e latelang:
\[
\text{B} + \text{H}_2\text{O} \rightleftharpoons \text{BH}^+ + \text{OH}^-
\]
ka \(\text{B}\) e le motheo o fokolang le \(\text{BH}^+\) e le cation e kopaneng.
Sephetho sa karohano ea motheo (\(K_b\)) se sebelisoa ho hlalosa matla a motheo o fokolang:
\[
K_b = \frac{[\text{BH}^+][\text{OH}^-]}{[\text{B}]}
\]
Lipotso tsa Mehlala le Puisano
Mohlala oa Potso ea 1: Asiti e Fokolang
Potso: Bala pH ea tharollo ea 0.1 M ea asiti ea acetic (\(\text{CH}_3\text{COOH}\)) haeba \(K_a\) ea asiti ea acetic e \(1.8 \makhetlo a 10^{-5}\).
Puisano:
1. Ngola equation ea karohano:
\[
\text{CH}_3\text{COOH} \rightleftharpoons \text{CH}_3\text{COO}^- + \text{H}^+
\]
2. Fumana hore na mahloriso a pele le phetoho ea mahloriso a qalile joang tafoleng ea ICE (Qalong, Phetoho, Tekano).
| | \(\text{CH}_3\text{COOH}\) | \(\text{CH}_3\text{COO}^-\) | \(\text{H}^+\) |
|——-|—————————-|———————-|——————–|
| Leqephe la pele | 0.1 M | 0 | 0 |
| Phetoho | -x | +x | +x |
| Tekano | 0.1 – x | x | x |
3. Amahanya \(K_a\) le mahloriso a ho leka-lekana:
\[
K_a = \frac{[H^+][CH_3COO^-]}{[CH_3COOH]} = \frac{x \cdot x}{0.1 – x}
\]
Kaha \(K_a\) e nyane, khopolo-taba \(x \ll 0.1\) hangata e nepahetse:
\[
K_a \hoo e ka bang \frac{x^2}{0.1}
\]
\[
1.8 \makgetlo a 10^{-5} = \frac{x^2}{0.1}
\]
\[
x^2 = 1.8 \makhetlo a 10^{-6}
\]
\[
x = 1.34 \makhetlo a 10^{-3}
\]
4. Bala pH:
\[
\text{pH} = -\log[H^+] = -\log(1.34 \makgetlo a 10^{-3}) = 2.87
\]
Mohlala oa Potso ea 2: Metheo e Fokolang
Potso: Bala pOH ea tharollo ea ammonia ea 0.05 M (\(\text{NH}_3\)) haeba \(K_b\) ea ammonia e le \(1.8 \makhetlo a 10^{-5}\).
Puisano:
1. Ngola equation ea karohano:
\[
\text{NH}_3 + \text{H}_2\text{O} \rightleftharpoons \text{NH}_4^+ + \text{OH}^-
\]
2. Fumana hore na mahloriso a pele a bile le phetoho ea mahloriso tafoleng ea ICE:
| | \(\mongolo{NH}_3\) | \(\mongolo{NH}_4^+\) | \(\mongolo{OH}^-\) |
|——-|——————–|———————-|——————|
| Leqephe la pele | 0.05 M | 0 | 0 |
| Phetoho | -x | +x | +x |
| Tekano | 0.05 – x | x | x |
3. Amahanya \(K_b\) le mahloriso a ho leka-lekana:
\[
K_b = \frac{[\text{NH}_4^+][\text{OH}^-]}{[\text{NH}_3]} = \frac{x \cdot x}{0.05 – x}
\]
Ho nka \(x \ll 0.05\):
\[
K_b \hoo e ka bang \frac{x^2}{0.05}
\]
\[
1.8 \makgetlo a 10^{-5} = \frac{x^2}{0.05}
\]
\[
x^2 = 9 \makhetlo a 10^{-7}
\]
\[
x = 3 \makhetlo a 10^{-4}
\]
4. Bala pOH:
\[
\text{pOH} = -\log[OH^-] = -\log(3 \makgetlo a 10^{-4}) = 3.52
\]
5. Fetolela ho pH haeba ho hlokahala:
\[
\mongolo{pH} = 14 – \mongolo{pOH} = 14 – 3.52 = 10.48
\]
Qetello
Ho utloisisa li-acid tse fokolang le metheo e fokolang ka mehlala ea mathata ho thusa haholo ho bolela esale pele boitšoaro ba tsona ba lik'hemik'hale tharollong. Ka ho utloisisa likhopolo tsa \(K_a\) le \(K_b\) le mokhoa oa ho fetolela mahloriso a li-ion ho pH kapa pOH, re ka sekaseka litharollo tse fapaneng maemong a thuto le a indasteri. Tsoela pele ho ikoetlisa ka mathata a fapaneng ho tebisa kutloisiso ea hau le bokhoni ba hau ba tlhahlobo ea lik'hemik'hale.
