Imibuzo Eyisibonelo Exoxa Ngezakhiwo Nemibono Yama-Acid Nezisekelo
Izakhiwo kanye nemibono yama-asidi kanye nezisekelo kuyizihloko ezibalulekile kukhemistri, kanye nokusetshenziswa okubanzi emikhakheni eyahlukahlukene, okuhlanganisa imboni, ikhemisi, kanye ne-biochemistry. Ukuqonda imiqondo eyisisekelo kanye nokusetshenziswa kwezakhiwo ze-acid-base kubalulekile kubafundi nakubacwaningi. Lesi sihloko sizoxoxa ngezibonelo eziningana zezinkinga eziphathelene nezakhiwo kanye nemibono yama-asidi kanye nezisekelo, kanye nezixazululo zazo, ukunikeza abafundi isithombe esicacile.
Imiqondo Eyisisekelo Yama-Acid Nezisekelo
Ngaphambi kokuba sibukeze imibuzo kanye nezingxoxo zayo, ake sibukeze eminye imiqondo eyisisekelo mayelana nama-asidi nezisekelo.
Okumuncu:
– Ama-asidi amakhemikhali anganikela ngama-ion e-hydrogen (H⁺) njengesixazululo.
– Ama-asidi anezakhiwo ze-asidi, isibonelo ukunambitheka okumuncu (njengoviniga) kanye nekhono lokusabela nezinsimbi.
Ibhesi:
– Isisekelo siyinhlanganisela engamukela ama-ion e-hydrogen noma iqhube ama-ion e-hydroxide (OH⁻) esixazululweni.
– Izisekelo zinezakhiwo eziyisisekelo, njengokunambitheka okubabayo kanye nokuthungwa okushelelayo (njengensipho).
Ithiyori Yesisekelo Se-Acid:
– Ithiyori ye-Arrhenius: Ama-asidi akhiqiza i-H⁺ kanti izisekelo zikhiqiza i-OH⁻ esixazululweni samanzi.
– Ithiyori kaBrønsted-Lowry: Ama-asidi angabanikeli be-H⁺ kanti izisekelo zingabamukeli be-H⁺.
– Ithiyori kaLewis: Ama-asidi angama-elektroni amukela ama-elektroni amabili kanti izisekelo zingabanikeli bama-elektroni amabili.
Imibuzo Nezingxoxo Eziyisibonelo
Isibonelo Umbuzo 1: Ukubala i-pH yesisombululo se-Acid Esiqinile
Umbuzo:
Bala i-pH yesisombululo se-HCl esingu-0,01 M.
Ingxoxo:
I-HCl iyi-asidi enamandla ezohlukana ngokuphelele nesisombululo ukuze kukhiqizwe i-H⁺ ne-Cl⁻. Ukuhlushwa kwe-H⁺ kufana nokuhlushwa kokuqala kwe-HCl.
\[ [H⁺] = 0,01 \, M \]
I-pH ichazwa njenge-logarithm engemihle yesisekelo esingu-10 sokuhlushwa kwe-hydrogen ion:
\[ \umbhalo{pH} = -\log[H⁺] \]
\[ \umbhalo{pH} = -\log(0,01) \]
\[ \umbhalo{pH} = 2 \]
Ngakho-ke, i-pH yesisombululo se-HCl esingu-0,01 M ingu-2.
Isibonelo Umbuzo 2: Ukubala i-pH yesisombululo sesisekelo esiqinile
Umbuzo:
Bala i-pH yesisombululo se-NaOH esingu-0,001 M.
Ingxoxo:
I-NaOH iyisisekelo esiqinile esizohlukana ngokuphelele nesisombululo, sikhiqize i-Na⁺ kanye ne-OH⁻. Ukuhlushwa kwe-OH⁻ kufana nokuhlushwa kokuqala kwe-NaOH.
\[ [OH⁻] = 0,001 \, M \]
I-PoH ichazwa njenge-logarithm engemihle yesisekelo esingu-10 sokuhlushwa kwe-ion ye-hydroxide:
\[ \umbhalo{pOH} = -\log[OH⁻] \]
\[ \umbhalo{pOH} = -\log(0,001) \]
\[ \umbhalo{pOH} = 3 \]
I-pH ne-pOH zihlobene nge-equation:
\[ \text{pH} + \text{pOH} = 14 \]
\[ \umbhalo{pH} = 14 – 3 \]
\[ \umbhalo{pH} = 11 \]
Ngakho-ke, i-pH yesisombululo se-NaOH esingu-0,001 M ingu-11.
Isibonelo 3: Ukubala i-pH ye-Acid Ebuthakathaka
Umbuzo:
Bala i-pH yesisombululo se-acetic acid esingu-0,1 M (CH₃COOH), esine-constant dissociation constant (Ka) ye-\( 1,8 \times 10^{-5} \).
Ingxoxo:
Ama-asidi abuthakathaka awahlukani ngokuphelele nesisombululo. Ukuze sibale i-pH, kumele siqale sithole ukuhlushwa kwama-ion e-H⁺ sisebenzisa inani le-Ka.
\[ CH_3COOH \rightleftharpoons H^+ + CH_3COO^- \]
Uma i-\( x \) ingukuhlushwa kwe-H⁺ okukhiqizwayo:
\[ Ka = \frac{{[H^+][CH_3COO^-]}}{{[CH_3COOH]}} \]
\[ Ka = \frac{{x \cdot x}}{{0,1 – x}} \]
Njengoba kuyi-asidi ebuthakathaka, cabanga ukuthi \( x \) incane kakhulu kangangokuthi \( 0,1 – x \cishe 0,1 \):
\[ 1,8 \izikhathi eziyi-10^{-5} = \frac{x^2}{0,1} \]
\[ x^2 = 1,8 \izikhathi eziyi-10^{-6} \]
\[ x = \sqrt{1,8 \izikhathi eziyi-10^{-6}} \]
\[ x \cishe 1,34 \izikhathi eziyi-10^{-3} \]
Ukuhlushwa kwama-ion e-H⁺ cishe ku-\( 1,34 \times 10^{-3} \):
\[ \umbhalo{pH} = -\log[H^+] \]
\[ \text{pH} = -\log(1,34 \times 10^{-3}) \]
\[ \text{pH} \cishe 2,87 \]
Ngakho-ke, i-pH yesisombululo se-0,1 M CH₃COOH icishe ibe ngu-2,87.
Isibonelo Umbuzo 4: Ukubala i-pH yesisekelo esibuthakathaka
Umbuzo:
Bala i-pH yesisombululo se-ammonia esingu-0,05 M (NH₃), esine-base dissociation constant (Kb) ye-\( 1,8 \times 10^{-5} \).
Ingxoxo:
Izisekelo ezibuthakathaka azihlukani ngokuphelele nesisombululo. Ukuze sibale i-pH, kumele siqale sithole ukuhlushwa kwama-ion e-OH⁻ sisebenzisa inani le-Kb.
\[ NH_3 + H_2O \rightleftharpoons NH_4^+ + OH^- \]
Uma \( x \) kungukuhlushwa kwe-OH⁻ okukhiqizwayo:
\[ Kb = \frac{{[NH_4^+][OH^-]}}{{[NH_3]}} \]
\[ Kb = \frac{{x \cdot x}}{{0,05 – x}} \]
Ake sithi \( x \) incane kakhulu kangangokuthi \( 0,05 – x \cishe 0,05 \):
\[ 1,8 \izikhathi eziyi-10^{-5} = \frac{x^2}{0,05} \]
\[ x^2 = 9,0 \izikhathi eziyi-10^{-7} \]
\[ x = \sqrt{9,0 \izikhathi eziyi-10^{-7}} \]
\[ x \cishe 9,49 \izikhathi eziyi-10^{-4} \]
Ukuhlushwa kwama-ion e-OH⁻ cishe ku-\( 9,49 \times 10^{-4} \):
\[ \umbhalo{pOH} = -\log[OH^-] \]
\[ \text{pOH} = -\log(9,49 \times 10^{-4}) \]
\[ \text{pOH} \cishe 3,02 \]
I-pH ne-pOH zihlobene nge-equation:
\[ \text{pH} + \text{pOH} = 14 \]
\[ \umbhalo{pH} = 14 – 3,02 \]
\[ \text{pH} \cishe 10,98 \]
Isibonelo Umbuzo 5: Ukungathathi hlangothi kwama-Acid nama-Base
Umbuzo:
Yimuphi umthamo wesisombululo se-NaOH esingu-0,1 M esidingekayo ukuze kuncishiswe i-50 mL yesisombululo se-HCl esingu-0,1 M?
Ingxoxo:
Ukusabela kokungathathi hlangothi phakathi kwe-asidi nesisekelo kukhiqiza amanzi nosawoti:
\[ HCl + NaOH \umcibisholo ongakwesokudla uNaCl + H_2O \]
Inani lama-moles e-HCl:
\[ n_{HCl} = Ubuningi \izikhathi zevolumu \]
\[ n_{HCl} = 0,1 \, M \izikhathi 0,05 \, L \]
\[ n_{HCl} = 0,005 \, mol \]
Ngenxa yokuthi i-mole ngayinye ye-HCl isabela ne-mole eyodwa ye-NaOH, inani lama-moles e-NaOH elidingekayo liyafana, okungukuthi ama-moles angu-0,005.
Umthamo we-NaOH uyadingeka:
\[ n_{NaOH} = Ubuningi_{NaOH} \izikhathi zevolumu \]
\[ Umqulu_{NaOH} = \frac{n_{NaOH}}{Umthamo_{NaOH}} \]
\[ Umqulu_{NaOH} = \frac{0,005 \, mol}{0,1 \, M} \]
\[ Ivolumu_{NaOH} = 0,05 \, L \]
\[ Ivolumu_{NaOH} = 50 \, mL \]
Ngakho-ke, kudingeka i-50 mL yesisombululo se-NaOH esingu-0,1 M ukuze kuncishiswe i-50 mL yesisombululo se-HCl esingu-0,1 M.
Ngokuxoxa ngemibuzo engenhla, sithemba ukuthi ukuqonda kwethu izakhiwo kanye nemibono yama-asidi kanye nezisekelo sekucacile. Lezi zakhiwo kanye nemibono zibaluleke kakhulu ekusetshenzisweni kwamakhemikhali kwansuku zonke, kusukela ekuhlaziyweni kwelabhorethri kuya embonini.
