Mohlala oa Lipotso tsa Puisano ea Hydrolysis ea Letsoai
Hydrolysis ea letsoai ke ketsahalo ea lik'hemik'hale e kenyeletsang karabelo ea letsoai le metsi, e hlahisang asiti kapa motheo e le sehlahisoa se latelang. Ts'ebetso ena hangata ke sehlooho sa bohlokoa lithutong tsa k'hemistri hobane ho utloisisa hydrolysis ea letsoai ho ka fana ka temohisiso ea motheo mabapi le litšobotsi tsa litharollo le ho thusa ho fumana pH ea litharollo. Sehloohong sena, re tla buisana ka mehlala e 'maloa ea mathata le litharollo tsa bona tse amanang le hydrolysis ea letsoai.
Mehopolo ea Motheo ea Hydrolysis ea Letsoai
Hydrolysis ea letsoai e etsahala ha letsoai le bola ka metsing 'me li-ion tsa lona li arabela le limolek'hule tsa metsi ho hlahisa asiti kapa motheo. Hase letsoai lohle le tla haelloa ke metsi ka metsing; a mang ha a nke lehlakore, ho bolelang hore ha a fetole pH ea tharollo. Leha ho le joalo, letsoai le leng le ka hlahisa litharollo tse nang le asiti kapa motheo, ho latela mohloli oa asiti le motheo o entseng letsoai.
Ho utloisisa mokhoa ona, ho bohlokoa ho tseba hore:
– Matswai a di-acid tse matla le metheo e matla (jwalo ka NaCl) hangata ha a fetelwe ke hydrolysis mme tharollo e dula e sa nke lehlakore.
– Matswai a di-acid tse fokolang le metheo e matla (jwalo ka CH3COONa) hangata a hlahisa ditharollo tsa motheo.
– Matswai a di-acid tse matla le metheo e fokolang (jwalo ka NH4Cl) hangata a hlahisa ditharollo tse nang le asiti.
– Matswai a di-asidi tse fokolang le metheo e fokolang a ka arabela le metsi mme a fumana pH ya ho qetela ho latela matla a amanang le asiti le metheo.
Lipotso tsa Mehlala le Puisano
Potso ea 1: Hydrolysis ea Potassium Acetate (CH3COOK)
Potso:
Na tharollo ea potassium acetate (CH3COOK) e na le asiti, ea motheo, kapa e sa nke lehlakore? Ngola karabelo ea hydrolysis e etsahalang 'me u fumane pH ea tharollo.
Puisano:
Potassium acetate (CH3COOK) ke letsoai la asiti e fokolang (acetic acid, CH3COOH) le motheo o matla (potassium hydroxide, KOH). Ho tsoa ho sena, re ka etsa qeto ea hore tharollo ea CH3COOK mohlomong ke ea motheo hobane ione ea acetate (CH3COO⁻) e ka hydrolyze ka metsing.
Karabelo ke ka tsela e latelang:
\[ CH_3COO^- + H_2O \rightleftharpoons CH_3COOH + OH^- \]
Li-ion tsa acetate (CH3COO⁻) li amohela liprothone (H⁺) tse tsoang metsing (H2O) ho etsa acetic acid (CH3COOH) le li-ion tsa hydroxide (OH⁻). Boteng ba li-ion tsa hydroxide (OH⁻) ka har'a tharollo bo etsa hore e be ea motheo.
Ho fumana pH, re hloka mahloriso a li-ion tsa OH⁻. Mohlala, re na le tharollo ea 0,1 M CH3COOK 'me ionization constant ea acetic acid (Ka) ke 1,8 × 10⁻⁵.
Mehato e nkiloeng ke:
1. Ho sebedisa motheo o sa fetoheng (Kb) bakeng sa ion ya CH3COO⁻:
\[ K_b = \frac{K_w}{K_a} = \frac{10^{-14}}{1,8 \makgetlo a 10^{-5}} = 5,56 \makgetlo a 10^{-10} \]
2. Arola li-ion tsa CH3COO⁻ ka har'a tharollo:
\[ K_b = \frac{[CH_3COOH][OH^-]}{[CH_3COO^-]} \]
A re re tekanyo ea karohano e be 'x':
\[ 5,56 \makgetlo a 10^{-10} = \frac{x^2}{0,1-x} \]
Ha re hlokomoloha \(x\) e nyane ho denominator, re ka nolofatsa:
\[ x^2 \hoo e ka bang 5,56 \ka makhetlo a 10^{-11} \Motsu o letona x = \sqrt{5,56 \ka makhetlo a 10^{-11}} = 7,45 \ka makhetlo a 10^{-6} \]
Ho tsepamisa maikutlo ha OH⁻:
\[ [OH^-] = 7,45 \makgetlo a 10^{-6} \]
pOH ea tharollo:
\[ pOH = -\log [OH^-] = -\log (7,45 \makgetlo a 10^{-6}) \hoo e ka bang 5,13 \]
Ho sebelisa kamano pakeng tsa pH le pOH:
\[ pH = 14 – pOH = 14 – 5,13 = 8,87 \]
Kahoo, tharollo ea CH3COOK ke ea motheo ka pH ea hoo e ka bang 8,87.
Potso ea 2: Hydrolysis ea Ammonium Chloride (NH4Cl)
Potso:
Na tharollo ea ammonium chloride (NH4Cl) e na le asiti, ea motheo, kapa e sa nke lehlakore? Ngola karabelo ea hydrolysis e etsahalang 'me u fumane pH ea tharollo.
Puisano:
Ammonium chloride (NH4Cl) ke letsoai la asiti e matla (HCl) le motheo o fokolang (NH3). Ho tsoa ho sena, re ka etsa qeto ea hore tharollo e na le asiti hobane ion ea ammonium (NH4⁺) e ka hydrolyze ka metsing.
Karabelo ke ka tsela e latelang:
\[ NH_4^+ + H_2O \rightleftharpoons NH_3 + H_3O^+ \]
Li-ion tsa Ammonium (NH4⁺) li fana ka liprothone (H⁺) ho limolek'hule tsa metsi (H2O) ho etsa ammonia (NH3) le li-ion tsa hydronium (H3O⁺). Boteng ba li-ion tsa hydronium (H3O⁺) tharollong ena bo etsa hore tharollo e be le asiti.
Mohlala, re na le tharollo ea 0,1 M NH4Cl. Sephetho sa motheo sa ionization (Kb) bakeng sa NH3 ke 1,8 × 10⁻⁵.
Mehato e nkiloeng ke:
1. Ho sebedisa asiti e sa fetoheng (Ka) bakeng sa ione ya NH4⁺:
\[ K_a = \frac{K_w}{K_b} = \frac{10^{-14}}{1,8 \makgetlo a 10^{-5}} = 5,56 \makgetlo a 10^{-10} \]
2. Arola li-ion tsa NH4⁺ ka har'a tharollo:
\[ K_a = \frac{[NH_3][H_3O^+]}{[NH_4^+]} \]
A re re tekanyo ea karohano e be 'x':
\[ 5,56 \makgetlo a 10^{-10} = \frac{x^2}{0,1-x} \]
Ha re hlokomoloha \(x\) e nyane ho denominator, re ka nolofatsa:
\[ x^2 \hoo e ka bang 5,56 \ka makhetlo a 10^{-11} \Motsu o letona x = \sqrt{5,56 \ka makhetlo a 10^{-11}} = 7,45 \ka makhetlo a 10^{-6} \]
Ho tsepamisa maikutlo ha H3O⁺:
\[ [H_3O^+] = 7,45 \makgetlo a 10^{-6} \]
pH ea tharollo:
\[ pH = -\log [H_3O^+] = -\log (7,45 \makgetlo a 10^{-6}) \hoo e ka bang 5,13 \]
Kahoo, tharollo ea NH4Cl e na le asiti e nang le pH e ka bang 5,13.
Mehlaleng ka bobeli e kaholimo, re bona kamoo ho tsebahatsa mofuta oa hydrolysis ho ka thusang ho fumana mofuta oa tharollo. Ka ho sebelisa ionization equilibrium constant (Ka kapa Kb) le likhopolo tse 'maloa tse bonolo, re ka rarolla mathata ana habonolo.
Puisano ena ea mathata a hydrolysis ea letsoai ha e koetlise feela tsebo ea tlhahlobo lipalo tsa lipalo empa hape e tebisa kutloisiso ea likhopolo tsa motheo tsa k'hemistri ea tharollo. Ho utloisisa kamoo li-ion tsa tšimoloho e fapaneng li kenyang liprothone kapa li-receptor limolek'huleng tsa metsi, le kamoo sena se amang pH ea tharollo, ke habohlokoa bakeng sa ho tseba lihlooho tse ngata tse tsoetseng pele k'hemistri.
