Nā nīnau hoʻohālike e kūkākūkā ana i nā waiwai a me nā manaʻo o nā waikawa a me nā kumu
He mau kumuhana koʻikoʻi nā waiwai a me nā manaʻo o nā waikawa a me nā kumu i ka kemika, me nā noi ākea ma nā ʻano like ʻole, me ka ʻoihana, ka lāʻau lapaʻau, a me ka biochemistry. He mea nui ka hoʻomaopopo ʻana i nā manaʻo kumu a me nā noi o nā waiwai waikawa-kumu no nā haumāna a me nā mea noiʻi. E kūkākūkā kēia ʻatikala i kekahi mau pilikia hoʻohālike e pili ana i nā waiwai a me nā manaʻo o nā waikawa a me nā kumu, me kā lākou mau hoʻonā, e hāʻawi i ka poʻe heluhelu i kahi kiʻi maopopo.
Nā Manaʻo Kumu o nā ʻAkika a me nā Kumu
Ma mua o ko mākou nānā ʻana i nā nīnau a me kā lākou mau kūkākūkā ʻana, e nānā hou kākou i kekahi mau manaʻo kumu e pili ana i nā waikawa a me nā kumu.
ʻAwaʻawa:
– He mau hui nā waikawa e hiki ke hāʻawi i nā iona hydrogen (H⁺) i loko o ka hopena.
– He mau ʻano ʻakika ko nā waikawa, e like me ka ʻono ʻawaʻawa (e like me ka vīnega) a me ka hiki ke hana me nā metala.
ʻO ka leo haʻahaʻa:
– He hui ka base e hiki ke ʻae i nā ion hydrogen a i ʻole ke alakaʻi i nā ion hydroxide (OH⁻) i loko o ka hopena.
– He mau waiwai kumu ko nā kumu, e like me ka ʻono ʻawaʻawa a me ke ʻano pahee (e like me ke kopa).
Kumumanaʻo Waikawa-Kumu:
– Ke kumumanaʻo ʻo Arrhenius: Hoʻopuka nā waikawa i ka H⁺ a hoʻopuka nā kumu i ka OH⁻ i loko o kahi hopena wai.
– Ke kumumanaʻo Brønsted-Lowry: He mau mea hāʻawi H⁺ nā waikawa a he mau mea lawe H⁺ nā kumu.
– Lewis Theory: He mau mea ʻae i nā hui uila nā waikawa a he mau mea hāʻawi i nā hui uila nā kumu.
Nā nīnau hoʻohālike a me nā kūkākūkā
Laʻana Nīnau 1: Ke helu ʻana i ka pH o kahi Waikawa Ikaika
Nīnau:
E helu i ka pH o kahi hopena HCl 0,01 M.
Kūkākūkā:
He waikawa ikaika ka HCl e hoʻokaʻawale loa i loko o ka hopena e hana i ka H⁺ a me Cl⁻. Ua like ka nui o ka H⁺ me ka nui mua o ka HCl.
\[ [H⁺] = 0,01 \, M \]
Ua wehewehe ʻia ka pH ʻo ia ka logarithm kumu maikaʻi ʻole 10 o ka nui o ka ion hydrogen:
\[ \kikokikona{pH} = -\log[H⁺] \]
\[ \kikokikona{pH} = -\log(0,01) \]
\[ \kikokikona{pH} = 2 \]
No laila, ʻo ka pH o kahi hopena HCl 0,01 M he 2.
Laʻana Nīnau 2: Ke helu ʻana i ka pH o kahi Waiwai Kumu Ikaika
Nīnau:
E helu i ka pH o kahi hopena 0,001 M NaOH.
Kūkākūkā:
He kumu ikaika ʻo NaOH e hoʻokaʻawale loa i loko o ka hopena, e hana ana i ka Na⁺ a me ka OH⁻. Ua like ka nui o ka OH⁻ me ka nui mua o ka NaOH.
\[ [OH⁻] = 0,001 \, M \]
Ua wehewehe ʻia ʻo PoH ʻo ia ka logarithm kumu maikaʻi ʻole 10 o ka nui o ka ion hydroxide:
\[ \kikokikona{pOH} = -\log[OH⁻] \]
\[ \kikokikona{pOH} = -\log(0,001) \]
\[ \kikokikona{pOH} = 3 \]
Pili ka pH a me ka pOH e ka hoohalike:
\[ \kikokikona{pH} + \kikokikona{pOH} = 14 \]
\[ \kikokikona{pH} = 14 – 3 \]
\[ \kikokikona{pH} = 11 \]
No laila, ʻo ka pH o kahi hopena 0,001 M NaOH he 11.
Laʻana 3: Ke helu ʻana i ka pH o kahi ʻakika nāwaliwali
Nīnau:
E helu i ka pH o kahi hopena 0,1 M acetic acid (CH₃COOH), nona ka acid dissociation constant (Ka) o \( 1,8 \times 10^{-5} \).
Kūkākūkā:
ʻAʻole hoʻokaʻawale loa nā waikawa nāwaliwali i loko o ka hopena. No ka helu ʻana i ka pH, pono mua mākou e hoʻoholo i ka nui o nā ion H⁺ me ka hoʻohana ʻana i ka waiwai Ka.
\[ CH_3COOH \rightleftharpoons H^+ + CH_3COO^- \]
Inā ʻo \( x \) ka nui o ka H⁺ i hana ʻia:
\[ Ka = \frac{{[H^+][CH_3COO^-]}}{{[CH_3COOH]}} \]
\[ Ka = \frac{{x \cdot x}}{{0,1 – x}} \]
ʻOiai he waikawa nāwaliwali ia, e manaʻo he liʻiliʻi loa ʻo \( x \) i hiki ai iā \( 0,1 – x \approx 0,1 \):
\[ 1,8 \times 10^{-5} = \frac{x^2}{0,1} \]
\[ x^2 = 1,8 \times 10^{-6} \]
\[ x = \sqrt{1,8 \times 10^{-6}} \]
\[ x \approx 1,34 \times 10^{-3} \]
ʻO ka nui o nā iona H⁺ ma kahi o \( 1,34 \times 10^{-3} \):
\[ \kikokikona{pH} = -\log[H^+] \]
\[ \text{pH} = -\log(1,34 \times 10^{-3}) \]
\[ \text{pH} \approx 2,87 \]
No laila, ʻo ka pH o kahi hopena 0,1 M CH₃COOH ma kahi o 2,87.
Laʻana Nīnau 4: Ke helu ʻana i ka pH o kahi Base nāwaliwali
Nīnau:
E helu i ka pH o kahi hopena ammonia (NH₃) 0,05 M, nona kahi kūpaʻa dissociation kumu (Kb) o \( 1,8 \times 10^{-5} \).
Kūkākūkā:
ʻAʻole hoʻokaʻawale loa nā kumu nāwaliwali i loko o ka hopena. No ka helu ʻana i ka pH, pono mua mākou e hoʻoholo i ka nui o nā ion OH⁻ me ka hoʻohana ʻana i ka waiwai Kb.
\[ NH_3 + H_2O \rightleftharpoons NH_4^+ + OH^- \]
Inā ʻo \( x \) ka nui o ka OH⁻ i hana ʻia:
\[ Kb = \frac{{[NH_4^+][OH^-]}}{{[NH_3]}} \]
\[ Kb = \frac{{x \cdot x}}{{0,05 – x}} \]
Manaʻo ʻia he liʻiliʻi loa ʻo \( x \) i hiki ai iā \( 0,05 – x \approx 0,05 \):
\[ 1,8 \times 10^{-5} = \frac{x^2}{0,05} \]
\[ x^2 = 9,0 \times 10^{-7} \]
\[ x = \sqrt{9,0 \times 10^{-7}} \]
\[ x \approx 9,49 \times 10^{-4} \]
ʻO ka nui o nā iona OH⁻ ma kahi o \( 9,49 \times 10^{-4} \):
\[ \kikokikona{pOH} = -\log[OH^-] \]
\[ \text{pOH} = -\log(9,49 \times 10^{-4}) \]
\[ \text{pOH} \approx 3,02 \]
Pili ka pH a me ka pOH e ka hoohalike:
\[ \kikokikona{pH} + \kikokikona{pOH} = 14 \]
\[ \kikokikona{pH} = 14 – 3,02 \]
\[ \text{pH} \approx 10,98 \]
Laʻana Nīnau 5: Hoʻopau ʻana i nā ʻakika a me nā kumu
Nīnau:
ʻEhia ka nui o ka hopena 0,1 M NaOH e pono ai e hoʻopau i 50 mL o ka hopena 0,1 M HCl?
Kūkākūkā:
ʻO ka hopena neutralization ma waena o ka waikawa a me ke kumu e hua mai ai ka wai a me ka paʻakai:
\[ HCl + NaOH \rightarrow NaCl + H_2O \]
Ka helu o nā mole o HCl:
\[ n_{HCl} = Molarity \times Volume \]
\[ n_{HCl} = 0,1 \, M \times 0,05 \, L \]
\[ n_{HCl} = 0,005 \, mol \]
No ka mea, hui pū kēlā me kēia mole o HCl me hoʻokahi mole o NaOH, ua like ka helu o nā mole o NaOH e pono ai, ʻo ia hoʻi he 0,005 mole.
Ka nui o ka NaOH e pono ai:
\[ n_{NaOH} = Molarity_{NaOH} \times Volume \]
\[ Leo_{NaOH} = \frac{n_{NaOH}}{ Molarity_{NaOH}} \]
\[ Leo_{NaOH} = \frac{0,005 \, mol}{0,1 \, M} \]
\[ Volume_{NaOH} = 0,05 \, L \]
\[ Volume_{NaOH} = 50 \, mL \]
No laila, pono 50 mL o ka hopena 0,1 M NaOH e hoʻopau i 50 mL o ka hopena 0,1 M HCl.
Ma ke kūkākūkā ʻana i nā nīnau ma luna, ke manaʻolana nei mākou e loaʻa kahi ʻike maopopo o nā waiwai a me nā manaʻo o nā waikawa a me nā kumu. He mea pili loa kēia mau waiwai a me nā manaʻo i nā noi kemika o kēlā me kēia lā, mai ka nānā ʻana i ka hale hana a hiki i ka ʻoihana.
