Isibonelo Semibuzo Yengxoxo Esekelwe Ku-Brønsted-Lowry Acid
Ama-asidi nezisekelo kuyimibono ebalulekile kumakhemikhali eye yathuthukiswa futhi yahlungwa ososayensi abaningi eminyakeni edlule. Enye yezinkolelo-mbono ezithandwa kakhulu yi-Brønsted-Lowry theory, eyaphakanyiswa nguJohannes Nicolaus Brønsted noThomas Martin Lowry ngo-1923. Le nkolelo-mbono inikeza umbono obanzi wokuthi ama-asidi nezisekelo zihlangana kanjani ekusabeleni kwamakhemikhali. Kulesi sihloko, sizoxoxa ngezinkinga eziningana zezibonelo ezihlobene nomqondo we-Brønsted-Lowry wama-asidi nezisekelo nokuthi singazixazulula kanjani.
Imiqondo Eyisisekelo Yama-Brønsted-Lowry Acids kanye Nezisekelo
Ngokusho kwethiyori kaBrønsted-Lowry, i-asidi yinto enganikela nge-proton (H+), kanti isisekelo yinto engamukela i-proton. Ekuphenduleni kwamakhemikhali, ama-asidi kanye nezisekelo kuyasebenzisana ngenqubo yokudlulisa i-proton, lapho i-compound eyodwa isebenza njenge-asidi ngokukhulula i-proton, kanti enye i-compound isebenza njengesisekelo ngokwamukela i-proton.
Izibonelo Zokusabela Kwe-Acid-Base
Isibonelo sokusabela okulula phakathi kwe-asidi nesisekelo ngokusho kwe-Brønsted-Lowry yikusabela phakathi kwe-copper(II) sulfate (H2SO4) kanye ne-sodium hydroxide (NaOH):
\[ \text{H}_2\text{SO}_4 + \text{NaOH} \rightarrow \text{NaHSO}_4 + \text{H}_2\text{O} \]
Kule mpendulo, i-sulfuric acid (H2SO4) isebenza njenge-Brønsted-Lowry acid ngoba inikela nge-proton (H+) ku-base NaOH, eyamukela i-proton.
Imibuzo Nezingxoxo Eziyisibonelo
Umbuzo 1: Ukuhlonza ama-Acid kanye nezisekelo
Umbuzo:
Thola ama-asidi nama-base e-Brønsted-Lowry kulezi zindlela ezilandelayo:
\[ \text{NH}_3 + \text{H}_2\text{O} \rightarrow \text{NH}_4^+ + \text{OH}^- \]
Ingxoxo:
Kulesi simo, i-ammonia (NH3) kanye namanzi (H2O) yizinto ezibangela ukusabela, kuyilapho ama-ion e-ammonium (NH4+) kanye nama-ion e-hydroxide (OH-) kuyizinto ezibangela ukusabela. Ake sibone ukuthi iyiphi esebenza njenge-asidi nokuthi iyiphi esebenza njengesisekelo.
– I-NH3 isebenza njengesisekelo ngoba yamukela ama-proton (H+) avela ku-H2O ukuze akhe i-NH4+.
– I-H2O isebenza njenge-asidi ngoba inikela nge-proton (H+) ku-NH3 ukuze yakhe i-OH-.
Ngakho-ke, kulokhu kusabela:
– I-NH3 iyisizinda saseBrønsted-Lowry.
– I-H2O iyi-asidi ye-Brønsted-Lowry.
Umbuzo 2: Ukubhala Ukusabela Kokuhlanganisa
Umbuzo:
Bhala ama-conjugate acid-base pairs kulezi zindlela ezilandelayo zokusabela:
\[ \text{HCl} + \text{H}_2\text{O} \rightarrow \text{H}_3\text{O}^+ + \text{Cl}^- \]
Ingxoxo:
Kule mpendulo, i-HCl isebenza njenge-Brønsted-Lowry acid ngokunikela nge-proton (H+) ku-H2O. Amanzi (H2O) ayamukela i-proton futhi asebenza njengesisekelo se-Brønsted-Lowry. Ngemva kokulahlekelwa yi-proton, i-HCl iphenduka ibe yi-Cl-, kanti i-H2O, ngemva kokuthola i-proton, iphenduka ibe yi-H3O+.
– I-Acid (HCl) kanye nesisekelo sayo esihlanganisiwe (Cl-)
– Isisekelo (H2O) kanye ne-conjugate acid yayo (H3O+)
Ngakho-ke, umbhangqwana we-conjugate acid-base kulokhu kusabela ngu:
– HCl/Cl-
– H2O / H3O+
Umbuzo 3: Ukubala i-pH yesisombululo se-Acid esibuthakathaka
Umbuzo:
Bala i-pH yesisombululo se-acetic acid esingu-0.1 M (CH3COOH) uma kwaziwa ukuthi i-acid dissociation constant (Ka) ingu-\(1.8 \times 10^{-5}\).
Ingxoxo:
I-Acetic acid iyi-asidi ebuthakathaka, futhi emanzini i-ionization yayo iyingxenye kuphela ngokwe-equation elandelayo:
\[ \text{CH}_3\text{COOH} \rightleftharpoons \text{CH}_3\text{COO}^- + \text{H}^+ \]
Izinyathelo zokubala i-pH yilezi ezilandelayo:
1. Setha ukubonakaliswa kokulingana usebenzisa ukuhlushwa kokuqala kanye noshintsho ekuhlushweni:
\[ \text{Ka} = \frac{[\text{CH}_3\text{COO}^-][\text{H}^+]}{[\text{CH}_3\text{COOH}]} \]
2. Faka esikhundleni amanani aziwayo bese uxazulula i-\([H^+]\):
\[ 1.8 \izikhathi 10^{-5} = \frac{x^2}{0.1 – x} \]
Njengoba i-\(x\) incane kakhulu uma iqhathaniswa ne-0.1, singalinganisa i-\(0.1 – x \cishe i-0.1\):
\[ 1.8 \izikhathi eziyi-10^{-5} = \frac{x^2}{0.1} \]
\[ x^2 = 1.8 \izikhathi eziyi-10^{-6} \]
\[ x = \sqrt{1.8 \izikhathi eziyi-10^{-6}} \]
\[ x \cishe 1.34 \izikhathi eziyi-10^{-3} \]
3. Bala i-pH:
\[ \umbhalo{pH} = -\umbhalo{H}^+] \]
\[ \text{pH} = -\log(1.34 \times 10^{-3}) \]
\[ \text{pH} \cishe 2.87 \]
Ngakho-ke, i-pH yesisombululo se-acetic acid esingu-0.1 M cishe ingu-2.87.
Umbuzo 4: Ukuhlonza Izixazululo Ze-Amphiprotic
Umbuzo:
Thola isixazululo se-amphiprotic ku-reaction elandelayo bese uchaza ukuthi kungani:
\[ \text{HCO}_3^- + \text{H}_2\text{O} \rightleftharpoons \text{H}_2\text{CO}_3 + \text{OH}^- \]
Ingxoxo:
Isixazululo se-amphiprotic yisisombululo esingasebenza njenge-asidi noma isisekelo, kuye ngezimo zokusabela. Esibonelweni sokusabela esingenhla:
– \(\text{HCO}_3^-\) isebenza njengesisekelo uma yamukela iphrothoni kusuka ku-\(\text{H}_2\text{O}\), ikhiqiza \(\text{H}_2\text{CO}_3\).
– \(\text{HCO}_3^-\) ingasebenza njenge-asidi ngaphansi kwezinye izimo, ikhulule i-proton futhi ikhiqize \(\text{CO}_3^{2-}\).
Lokhu kukhombisa ukuthi i-ion ye-\(\text{HCO}_3^-\) iyi-amphiprotic. Ingasebenza njenge-asidi (umnikeli we-proton) kanye nesisekelo (ummukeli we-proton), kuye ngokuthi iyiphi enye into esabela ngayo.
Ngalezi zinkinga zezibonelo, singaqonda kangcono ukuthi i-Brønsted-Lowry acid-base theory isetshenziswa kanjani ukuhlaziya nokubikezela ukusebenzisana kwamakhemikhali. Ukuqonda okuqinile kwale theory kuyisisekelo sezinhlelo zokusebenza eziningi kumakhemikhali, i-biochemistry, kanye nezinye isayensi.
