Mehlala ea Lipotso Tse Buisanang ka Litharollo tsa Buffer
Tharollo ea buffer, eo hangata e bitsoang buffer, ke tharollo e bolokang pH ea eona leha ho eketsoa asiti e matla kapa motheo o monyane. Bokhoni bona bo etsa hore litharollo tsa buffer e be tsa bohlokoa lits'ebetsong tse fapaneng tsa lik'hemik'hale, tsa baeloji, esita le tsa indasteri. Sehloohong sena, re tla hlahloba mehlala e meng le ho buisana ka litharollo tsa buffer.
Ho Utloisisa Litharollo tsa Buffer
Hangata ditharollo tsa buffer di bopilwe ka motswako wa asiti e fokolang le motheo wa yona o kopaneng kapa motheo o fokolang le asiti ya yona e kopaneng. Ha asiti kapa motheo o eketswa ditharollong tsena, karabelo e hlahang e thusa ho boloka pH ya tharollo ka hara tekanyo e itseng. Moelelong ona, pH ke tekanyo ya asiti kapa alkalinity ya tharollo.
Mosebetsi le Bohlokoa ba Litharollo tsa Buffer
Litharollo tsa buffer li na le karolo ea bohlokoa masimong a fapaneng:
1. Biochemistry: Likarabelo tse ngata tsa enzymatic le tsa 'mele li etsahala ho pH e itseng, kahoo litharollo tsa buffer li thusa ho boloka maemo a matle.
2. Indasteri: Liindastering tsa lijo le meriana, taolo e nepahetseng ea pH e bohlokoa bakeng sa boleng le polokeho ea sehlahisoa.
3. Liteko tsa Lik'hemik'hale: Ka laboratoring, litharollo tsa buffer li sebelisoa ho laola pH nakong ea liketso tsa lik'hemik'hale.
Kamoo Litharollo tsa Buffer li Sebetsang Kateng
Litharollo tsa buffer li sebetsa ho latela molao-motheo oa tekano. Bakeng sa tharollo e nang le asiti e fokolang \(HA \) le letsoai la eona la motheo le kopaneng \(A^- \), ho eketsoa ha asiti kapa motheo o monyenyane ho tla baka karabelo ea ho falla ntle le phetoho e kholo mahlorisong a li-ion tsa \(H^+ \).
Lipotso tsa Mehlala le Puisano
Ho e utloisisa haholoanyane, ha re sekasekeng lipotso le lipuisano tse ling tse amanang le litharollo tsa buffer.
Potso ea 1: Ho bala pH ea Tharollo ea Acid Buffer
Potso:
Tharollo ea buffer e etsoa ka ho kopanya 0,1 mol ea asiti ea acetic (CH₃COOH) le 0,1 mol ea sodium acetate (CH₃COONa) ka litara e le 'ngoe ea tharollo. Khakanyo ea karohano ea asiti ea acetic (\( K_a \)) ke \( 1,8 \makhetlo a 10^{-5} \). Bala pH ea tharollo.
Puisano:
Tharollo ena ea buffer e na le asiti e fokolang (CH₃COOH) le motheo oa eona oa conjugate (CH₃COO⁻). Re ka sebelisa equation ea Henderson-Hasselbalch ho bala pH ea tharollo ea buffer:
\[ \text{pH} = \text{p}K_a + \log \left( \frac{[A^-]}{[HA]} \right) \]
Moo:
\[ \text{p}K_a = -\log (K_a) \]
\[ \text{p}K_a = -\log (1,8 \makgetlo a 10^{-5}) \]
\[ \text{p}K_a \hoo e ka bang 4,74 \]
Kaha mahloriso a \( [A^-] \) le \( [HA] \) a tšoana (0,1 M):
\[ \text{pH} = 4,74 + \log \left( \frac{[0,1]}{[0,1]} \right) \]
\[ \mongolo{pH} = 4,74 + \log(1) \]
\[ \mongolo{pH} = 4,74 \]
Kahoo, pH ea tharollo ea buffer ke 4,74.
Potso ea 2: Ho eketsa asiti ho Tharollo ea Buffer
Potso:
Phetoho ea pH ke efe haeba 0,01 mol ea HCl e eketsoa ho litara e le 1 ea tharollo ea buffer ho tsoa Potsong ea 1?
Puisano:
Ho eketsoa ha HCl ho tla eketsa mahloriso a \( H^+ \) ka hara tharollo. Karabelo e hlahang ke:
\[ \text{H}^+ + \text{CH}_3\text{COO}^- \rightarrow \text{CH}_3\text{COOH} \]
Re hloka ho bala hore na ke li-moles tse kae tsa \( H^+ \) le hore na li ama mahloriso a \( \text{CH}_3\text{COOH} \) le \( \text{CH}_3\text{COO}^- \).
Qalong:
\[ [\text{CH}_3\text{COO}^-] = 0,1 \, \text{mol} \]
\[ [\text{CH}_3\text{COOH}] = 0,1 \, \text{mol} \]
Kamora ho eketsa 0,01 mol ea HCl:
\[ [\text{CH}_3\text{COO}^-] = 0,1 – 0,01 = 0,09 \, \text{mol} \]
\[ [\text{CH}_3\text{COOH}] = 0,1 + 0,01 = 0,11 \, \text{mol} \]
Sebelisa equation ea Henderson-Hasselbalch ho bala pH e ncha:
\[ \text{pH} = \text{p}K_a + \log \left( \frac{[A^-]}{[HA]} \right) \]
\[ \text{pH} = 4,74 + \log \left( \frac{0,09}{0,11} \right) \]
\[ \mongolo{pH} = 4,74 + \log(0,818) \]
\[ \mongolo{pH} = 4,74 + (-0,088) \]
\[ \mongolo{pH} = 4,65 \]
Kahoo, pH ea tharollo ea buffer kamora ho eketsa HCl e fetoha ho tloha ho 4,74 ho ea ho 4,65.
Potso ea 3: Ho eketsa Motheo Tharollong ea Buffer
Potso:
Phetoho ea pH ke efe haeba 0,01 mol ea NaOH e eketsoa ho litara e le 1 ea tharollo ea buffer ho tsoa Potsong ea 1?
Puisano:
Ho eketsoa ha NaOH ho tla fokotsa mahloriso a H⁺ tharollong ka OH⁻ ho tsoa ho NaOH. Karabelo e hlahang:
\[ \text{OH}^- + \text{CH}_3\text{COOH} \rightarrow \text{CH}_3\text{COO}^- + \text{H}_2\text{O} \]
Qalong:
\[ [\text{CH}_3\text{COOH}] = 0,1 \, \text{mol} \]
\[ [\text{CH}_3\text{COO}^-] = 0,1 \, \text{mol} \]
Kamora ho eketsa 0,01 mol ea NaOH:
\[ [\text{CH}_3\text{COOH}] = 0,1 – 0,01 = 0,09 \, \text{mol} \]
\[ [\text{CH}_3\text{COO}^-] = 0,1 + 0,01 = 0,11 \, \text{mol} \]
Sebelisa equation ea Henderson-Hasselbalch ho bala pH e ncha:
\[ \text{pH} = \text{p}K_a + \log \left( \frac{[A^-]}{[HA]} \right) \]
\[ \text{pH} = 4,74 + \log \left( \frac{0,11}{0,09} \right) \]
\[ \mongolo{pH} = 4,74 + \log(1,222) \]
\[ \mongolo{pH} = 4,74 + 0,087 \]
\[ \mongolo{pH} = 4,83 \]
Kahoo, pH ea tharollo ea buffer kamora ho eketsa NaOH e fetoha ho tloha ho 4,74 ho ea ho 4,83.
Potso ea 4: Ho Fumana Sebopeho sa Buffer ka pH e itseng
Potso:
Ho etsa litara e le 1 ea tharollo ea buffer ka pH 5,0 ho sebelisoa asetic acid (CH₃COOH) le sodium acetate (CH₃COONa), ho hlokahala limole tse kae tsa karolo ka 'ngoe? \( K_a \) ea asetic acid ke \( 1,8 \makhetlo a 10^{-5} \).
Puisano:
Sebelisa equation ea Henderson-Hasselbalch:
\[ \text{pH} = \text{p}K_a + \log \left( \frac{[A^-]}{[HA]} \right) \]
Taba ea pele, bala pKₐ:
\[ \text{p}K_a = -\log (1,8 \makgetlo a 10^{-5}) \]
\[ \text{p}K_a \hoo e ka bang 4,74 \]
Ebe o kenya boleng ba pH boo o bo batlang:
\[ 5,0 = 4,74 + \log \left( \frac{[A^-]}{[HA]} \right) \]
\[ 0,26 = \log \left( \frac{[A^-]}{[HA]} \right) \]
Ho sebelisa thepa ea li-logarithm:
\[ \frac{[A^-]}{[HA]} = 10^{0,26} \]
\[ \frac{[A^-]}{[HA]} \hoo e ka bang 1,82 \]
Sena se bolela hore bakeng sa mole e le 'ngoe ea CH₃COOH, ho hlokahala limole tse 1,82 tsa CH₃COONa. Bakeng sa karolelano ena ka litara e le 'ngoe:
Mohlala, ha re re CH₃COOH = x mol, kahoo CH₃COONa = 1,82x mol. Bophahamo bohle ke (x + 1.82x) = 2,82x mol, kaha re etsa litara e le 1 ea buffer, joale:
\[x + 1.82x = 1 \]
\[ 2.82x = 1 \]
\[ x = \frac{1}{2.82} \hoo e ka bang 0.355 \]
Kahoo, sebopeho se hlokahalang:
– CH₃COOH: 0,355 mol
– CH₃COONA: 1,82 0,355 ≈ 0,646 mol
Ka hona re hloka 0,355 mol ea asiti ea acetic le 0,646 mol ea sodium acetate ho etsa litara e le 'ngoe ea tharollo ea buffer ka pH ea 5,0.
Sengoloa sena se hlahisa mehlala e fapaneng ea mathata a amanang le litharollo tsa buffer le lipuisano tsa tsona ho fana ka kutloisiso e tebileng ea mohopolo ona. Re tšepa hore tlhahisoleseling ena e tla thusa ho utloisisa hore na litharollo tsa buffer li sebetsa joang le lits'ebetso tsa tsona maemong a fapaneng.
