Laʻana o nā nīnau kūkākūkā Brønsted-Lowry Acid-Base
He mau manaʻo koʻikoʻi nā waikawa a me nā kumu i ka kemika i hoʻomohala ʻia a hoʻomaʻemaʻe ʻia e nā ʻepekema he nui i nā makahiki. ʻO kekahi o nā kumumanaʻo kaulana loa ʻo ia ke kumumanaʻo Brønsted-Lowry, i hāpai ʻia e Johannes Nicolaus Brønsted lāua ʻo Thomas Martin Lowry i ka makahiki 1923. Hāʻawi kēia kumumanaʻo i kahi ʻike ākea o ke ʻano o ka launa pū ʻana o nā waikawa a me nā kumu i nā hopena kemika. Ma kēia ʻatikala, e kūkākūkā mākou i kekahi mau pilikia hoʻohālike e pili ana i ka manaʻo Brønsted-Lowry o nā waikawa a me nā kumu a pehea e hoʻoponopono ai iā lākou.
Nā Manaʻo Kumu o nā Waikawa a me nā Kumu Brønsted-Lowry
Wahi a ke kumumanaʻo Brønsted-Lowry, he mea hiki ke hāʻawi i kahi proton (H+) ka waikawa, a he mea hiki ke ʻae i kahi proton ke kumu. I nā hopena kemika, launa pū nā waikawa a me nā kumu ma o ke kaʻina hana hoʻoili proton, kahi e hana ai kekahi hui ma ke ʻano he waikawa ma ka hoʻokuʻu ʻana i kahi proton, a hana kekahi hui ma ke ʻano he kumu ma ka ʻae ʻana i kahi proton.
Nā Laʻana o nā Hana ʻAkika-Base
ʻO kahi laʻana o kahi hopena maʻalahi ma waena o kahi waikawa a me kahi kumu e like me ke kumumanaʻo Brønsted-Lowry ʻo ia ka hopena ma waena o ke keleawe (II) sulfate (H2SO4) a me ka sodium hydroxide (NaOH):
\[ \text{H}_2\text{SO}_4 + \text{NaOH} \rightarrow \text{NaHSO}_4 + \text{H}_2\text{O} \]
Ma kēia hopena, hana ka waikawa sulfuric (H2SO4) ma ke ʻano he waikawa Brønsted-Lowry no ka mea hāʻawi ia i kahi proton (H+) i ke kumu NaOH, ka mea e ʻae i ka proton.
Nā nīnau hoʻohālike a me nā kūkākūkā
Nīnau 1: Ke ʻIke ʻana i nā ʻAkika a me nā Kumu
Nīnau:
E ʻike i nā waikawa a me nā kumu Brønsted-Lowry i nā hopena aʻe:
\[ \kikokikona{NH}_3 + \kikokikona{H}_2\kikokikona{O} \rightarrow \kikokikona{NH}_4^+ + \kikokikona{OH}^- \]
Kūkākūkā:
Ma kēia hana, ʻo ka ammonia (NH3) a me ka wai (H2O) nā mea hana, ʻoiai ʻo nā ion ammonium (NH4+) a me nā ion hydroxide (OH-) nā huahana. E nānā kākou i ka mea e hana ana ma ke ʻano he waikawa a me ka mea e hana ana ma ke ʻano he kumu.
– Hana ʻo NH3 ma ke ʻano he kumu no ka mea ke ʻae nei ia i nā protons (H+) mai H2O e hana iā NH4+.
– Hana ʻo H2O ma ke ʻano he waikawa no ka mea hāʻawi ia i kahi proton (H+) i NH3 e hana i ka OH-.
No laila, ma kēia hana:
– He kumu Brønsted-Lowry ʻo NH3.
– He waikawa Brønsted-Lowry ka H2O.
Nīnau 2: Ke kākau ʻana i nā hopena hoʻohuihui
Nīnau:
E kākau i nā hui acid-base conjugate no nā hopena aʻe:
\[ \kikokikona{HCl} + \kikokikona{H}_2\kikokikona{O} \rightarrow \kikokikona{H}_3\kikokikona{O}^+ + \kikokikona{Cl}^- \]
Kūkākūkā:
Ma kēia hopena, hana ʻo HCl ma ke ʻano he waikawa Brønsted-Lowry ma ka hāʻawi ʻana i kahi proton (H+) i H2O. ʻAe ka wai (H2O) i ka proton a hana ma ke ʻano he kumu Brønsted-Lowry. Ma hope o ka nalowale ʻana o kahi proton, lilo ʻo HCl i Cl-, a ʻo H2O, ma hope o ka loaʻa ʻana o kahi proton, lilo i H3O+.
– ʻAkika (HCl) a me kona kumu hui (Cl-)
– Kumu (H2O) a me kona waikawa hui pū ʻia (H3O+)
No laila, ʻo ka hui acid-base conjugate i loko o kēia hopena:
– HCl / Cl-
– H2O / H3O+
Nīnau 3: Ke helu ʻana i ka pH o kahi hopena waikawa nāwaliwali
Nīnau:
E helu i ka pH o kahi hopena 0.1 M o ka waikawa acetic (CH3COOH) inā ʻike ʻia ʻo ke kūpaʻa dissociation waikawa (Ka) he \(1.8 \times 10^{-5}\).
Kūkākūkā:
He waikawa nāwaliwali ka waikawa ʻakika, a i loko o ka wai e hoʻokahe hapa wale ia e like me ke kaulike ma lalo nei:
\[ \text{CH}_3\text{COOH} \rightleftharpoons \text{CH}_3\text{COO}^- + \text{H}^+ \]
ʻO nā ʻanuʻu no ka helu ʻana i ka pH penei:
1. E hoʻonohonoho i ka hōʻike kaulike me ka hoʻohana ʻana i ka noʻonoʻo mua a me ka loli o ka noʻonoʻo:
\[ \kikokikona{Ka} = \frac{[\kikokikona{CH}_3\kikokikona{COO}^-][\kikokikona{H}^+]}{[\kikokikona{CH}_3\kikokikona{COOH}]} \]
2. E pani i nā waiwai i ʻike ʻia a hoʻoponopono no \([H^+]\):
\[ 1.8 \times 10^{-5} = \frac{x^2}{0.1 – x} \]
ʻOiai he liʻiliʻi loa ʻo \(x\) i hoʻohālikelike ʻia me 0.1, hiki iā mākou ke hoʻokokoke aku iā \(0.1 – x \approx 0.1\):
\[ 1.8 \times 10^{-5} = \frac{x^2}{0.1} \]
\[ x^2 = 1.8 \times 10^{-6} \]
\[ x = \sqrt{1.8 \times 10^{-6}} \]
\[ x \approx 1.34 \times 10^{-3} \]
3. E helu i ka pH:
\[ \kikokikona{pH} = -\log[\kikokikona{H}^+] \]
\[ \text{pH} = -\log(1.34 \times 10^{-3}) \]
\[ \text{pH} \approx 2.87 \]
No laila, ʻo ka pH o kahi hopena waikawa M acetic 0.1 ma kahi o 2.87.
Nīnau 4: Ke ʻike ʻana i nā hoʻonā Amphiprotic
Nīnau:
E kuhikuhi i ka hopena amphiprotic i loko o ka hopena aʻe a wehewehe i ke kumu:
\[ \text{HCO}_3^- + \text{H}_2\text{O} \rightleftharpoons \text{H}_2\text{CO}_3 + \text{OH}^- \]
Kūkākūkā:
ʻO kahi hopena amphiprotic kahi hopena e hiki ke hana ma ke ʻano he waikawa a i ʻole he kumu, ma muli o nā kūlana hopena. Ma ka laʻana o ka hopena ma luna:
– Hana ʻo \(\text{HCO}_3^-\) ma ke ʻano he kumu ke ʻae ʻo ia i kahi proton mai \(\text{H}_2\text{O}\), e hana ana i \(\text{H}_2\text{CO}_3\).
– Hiki iā \(\text{HCO}_3^-\) ke hana ma ke ʻano he waikawa ma lalo o nā kūlana ʻē aʻe, e hoʻokuʻu ana i kahi proton a hana i ka \(\text{CO}_3^{2-}\).
Hōʻike kēia he amphiprotic ka ion \(\text{HCO}_3^-\). Hiki iā ia ke hana ma ke ʻano he waikawa (mea hāʻawi proton) a me ke kumu (mea lawe proton), ma muli o ka mea ʻē aʻe āna e hana ai.
Me kēia mau pilikia hoʻohālike, hiki iā mākou ke hoʻomaopopo maikaʻi i ke ʻano o ka hoʻohana ʻia ʻana o ke kumumanaʻo acid-base Brønsted-Lowry e kālailai a wānana i nā pilina kemika. ʻO ka hoʻomaopopo paʻa ʻana i kēia kumumanaʻo ke kumu no nā noi he nui i ka kemika, biochemistry, a me nā ʻepekema ʻē aʻe.
