Isibonelo Semibuzo Yengxoxo Ye-Salt Hydrolysis
I-salt hydrolysis iyinto yamakhemikhali ehilela ukusabela kosawoti namanzi, okukhiqiza i-asidi noma isisekelo njengomkhiqizo ophumayo. Le nqubo ivame ukuba yisihloko esibalulekile ezifundweni zamakhemikhali ngoba ukuqonda i-salt hydrolysis kunganikeza ukuqonda okuyisisekelo ngezakhiwo zezixazululo futhi kusize ekunqumeni i-pH yezixazululo. Kulesi sihloko, sizoxoxa ngezinkinga eziningana zezibonelo kanye nezixazululo zazo ezihlobene ne-salt hydrolysis.
Imiqondo Eyisisekelo Yokuhlanzwa Kosawoti
Ukushiswa kukasawoti kwenzeka lapho usawoti ubola emanzini futhi ama-ion awo asabela nama-molecule amanzi ukuze akhiqize i-asidi noma isisekelo. Akuwona wonke usawoti ozoshiswa ngamanzi; amanye awashintshi i-pH yesisombululo. Kodwa-ke, amanye usawoti angakhiqiza izixazululo ezine-asidi noma eziyisisekelo, kuye ngokuthi umthombo we-asidi nesisekelo esakha usawoti.
Ukuze uqonde le ndlela, kubalulekile ukwazi ukuthi:
– Usawoti wama-asidi aqinile kanye nezisekelo eziqinile (njenge-NaCl) ngokuvamile awudluli ku-hydrolysis futhi isixazululo sihlala singathathi hlangothi.
– Usawoti wama-asidi abuthakathaka kanye nezisekelo eziqinile (njenge-CH3COONa) ngokuvamile ukhiqiza izixazululo eziyisisekelo.
– Usawoti wama-asidi aqinile kanye nezisekelo ezibuthakathaka (njenge-NH4Cl) ngokuvamile ukhiqiza izixazululo ze-asidi.
– Usawoti wama-asidi abuthakathaka kanye nezisekelo ezibuthakathaka ungasabela namanzi futhi unqume i-pH yokugcina kuye ngamandla ahlobene e-asidi kanye nesekelo.
Imibuzo Eyisibonelo Nengxoxo
Umbuzo 1: I-Hydrolysis ye-Potassium Acetate (CH3COOK)
Umbuzo:
Ingabe isisombululo se-potassium acetate (CH3COOK) sine-acidic, siyisisekelo, noma singathathi hlangothi? Bhala ukusabela kwe-hydrolysis okwenzekayo bese unquma i-pH yesisombululo.
Ingxoxo:
I-Potassium acetate (CH3COOK) usawoti we-asidi ebuthakathaka (i-acetic acid, i-CH3COOH) kanye nesisekelo esiqinile (i-potassium hydroxide, i-KOH). Kusukela kulokhu, singaphetha ngokuthi isisombululo se-CH3COOK cishe siyisisekelo ngoba i-acetate ion (CH3COO⁻) ingamanzisa emanzini.
Ukusabela kungokulandelayo:
\[ CH_3COO^- + H_2O \rightleftharpoons CH_3COOH + OH^- \]
Ama-ion e-acetate (CH3COO⁻) amukela ama-proton (H⁺) avela emanzini (H2O) ukuze akhe i-acetic acid (CH3COOH) kanye nama-ion e-hydroxide (OH⁻). Ukuba khona kwama-ion e-hydroxide (OH⁻) esixazululweni kwenza kube lula.
Ukuze sinqume i-pH, sidinga ukuhlushwa kwama-ion angu-OH⁻. Isibonelo, sinesisombululo se-0,1 M CH3COOK kanye ne-ionization constant ye-acetic acid (Ka) ingu-1,8 × 10⁻⁵.
Izinyathelo ezithathiwe yilezi:
1. Ukusebenzisa i-base constant (Kb) ye-CH3COO⁻ ion:
\[ K_b = \frac{K_w}{K_a} = \frac{10^{-14}}{1,8 \times 10^{-5}} = 5,56 \times 10^{-10} \]
2. Hlukanisa ama-ion e-CH3COO⁻ esixazululweni:
\[ K_b = \frac{[CH_3COOH][OH^-]}{[CH_3COO^-]} \]
Vumela izinga lokuzihlukanisa libe 'x':
\[ 5,56 \izikhathi ezingu-10^{-10} = \frac{x^2}{0,1-x} \]
Uma singayinaki into encane ku-denominator, singenza kube lula:
\[ x^2 \cishe 5,56 \izikhathi 10^{-11} \Umcibisholo Ongakwesokudla x = \sqrt{5,56 \izikhathi 10^{-11}} = 7,45 \izikhathi 10^{-6} \]
Ukuhlushwa kwe-OH⁻:
\[ [OH^-] = 7,45 \izikhathi ezingu-10^{-6} \]
i-pOH yesisombululo:
\[ pOH = -\log [OH^-] = -\log (7,45 \times 10^{-6}) \cishe 5,13 \]
Ukusebenzisa ubudlelwano phakathi kwe-pH ne-pOH:
\[ pH = 14 – pOH = 14 – 5,13 = 8,87 \]
Ngakho-ke, isixazululo se-CH3COOK siyisisekelo nge-pH engaba ngu-8,87.
Umbuzo 2: I-Hydrolysis ye-Ammonium Chloride (NH4Cl)
Umbuzo:
Ingabe isixazululo se-ammonium chloride (NH4Cl) sinobuthi, siyisisekelo, noma singathathi hlangothi? Bhala ukusabela kwe-hydrolysis okwenzekayo bese unquma i-pH yesisombululo.
Ingxoxo:
I-Ammonium chloride (NH4Cl) iyisawoti ye-asidi enamandla (HCl) kanye nesisekelo esibuthakathaka (NH3). Kusukela kulokhu, singaphetha ngokuthi ikhambi line-asidi ngoba i-ammonium ion (NH4⁺) ingamanzisa emanzini.
Ukusabela kungokulandelayo:
\[ NH_4^+ + H_2O \rightleftharpoons NH_3 + H_3O^+ \]
Ama-ion e-ammonium (NH4⁺) anikela ngama-proton (H⁺) kuma-molecule amanzi (H2O) ukuze akhe i-ammonia (NH3) kanye nama-ion e-hydronium (H3O⁺). Ukuba khona kwama-ion e-hydronium (H3O⁺) kulesi sixazululi kubangela ukuthi isixazululi sibe ne-asidi.
Isibonelo, sinesisombululo se-0,1 M NH4Cl. I-base ionization constant (Kb) ye-NH3 ingu-1,8 × 10⁻⁵.
Izinyathelo ezithathiwe yilezi:
1. Ukusebenzisa i-acid constant (Ka) ye-NH4⁺ ion:
\[ K_a = \frac{K_w}{K_b} = \frac{10^{-14}}{1,8 \times 10^{-5}} = 5,56 \times 10^{-10} \]
2. Hlukanisa ama-ion e-NH4⁺ esixazululweni:
\[ K_a = \frac{[NH_3][H_3O^+]}{[NH_4^+]} \]
Vumela izinga lokuzihlukanisa libe 'x':
\[ 5,56 \izikhathi ezingu-10^{-10} = \frac{x^2}{0,1-x} \]
Uma singayinaki into encane ku-denominator, singenza kube lula:
\[ x^2 \cishe 5,56 \izikhathi 10^{-11} \Umcibisholo Ongakwesokudla x = \sqrt{5,56 \izikhathi 10^{-11}} = 7,45 \izikhathi 10^{-6} \]
Ukuhlushwa kwe-H3O⁺:
\[ [H_3O^+] = 7,45 \izikhathi ezingu-10^{-6} \]
i-pH yesisombululo:
\[ pH = -\log [H_3O^+] = -\log (7,45 \times 10^{-6}) \cishe 5,13 \]
Ngakho-ke, isixazululo se-NH4Cl sine-asidi ene-pH engaba ngu-5,13.
Kuzo zombili izibonelo ezingenhla, sibona ukuthi ukuhlonza uhlobo lwe-hydrolysis kungasiza kanjani ekunqumeni uhlobo lwesisombululo. Ngokusebenzisa i-ionization equilibrium constant (Ka noma Kb) kanye nokucabanga okumbalwa okulula, singazixazulula kalula lezi zinkinga.
Le ngxoxo ngezinkinga ze-salt hydrolysis ayiqeqeshi nje kuphela amakhono okuhlaziya ekubaleni kwezibalo kodwa futhi ijulisa ukuqonda kwemibono eyisisekelo ye-solution chemistry. Ukuqonda ukuthi ama-ion emvelaphi ehlukahlukene anikela kanjani ama-proton noma ama-acceptors kuma-molecule amanzi, nokuthi lokhu kuthinta kanjani i-pH yesisombululo, kubalulekile ekuqondeni izihloko eziningi ezithuthukile ku-chemistry.
