Tauira o ngā Pātai Kōrero mō te Waikawa-Pūtake Brønsted-Lowry
He ariā nui ngā waikawa me ngā kawakore i roto i te matū, kua whakawhanakehia, kua whakatikatikaina hoki e te tini o ngā kaipūtaiao i roto i ngā tau. Ko tētahi o ngā ariā rongonui ko te ariā Brønsted-Lowry, i whakatakotoria e Johannes Nicolaus Brønsted rāua ko Thomas Martin Lowry i te tau 1923. Mā tēnei ariā ka whānui ake te tirohanga mō te taunekeneke a ngā waikawa me ngā kawakore i roto i ngā tauhohenga matū. I roto i tēnei tuhinga, ka matapakihia e mātou ētahi tauira raruraru e pā ana ki te ariā Brønsted-Lowry mō ngā waikawa me ngā kawakore, me pēhea hoki te whakaoti i aua raruraru.
Ngā Ariā Taketake o ngā Waikawa me ngā Kawenga Brønsted-Lowry
E ai ki te ariā a Brønsted-Lowry, ko te waikawa he matū ka taea te tuku i te pūrotene (H+), ko te kawakore ia he matū ka taea te tango i te pūrotene. I roto i ngā tauhohenga matū, ka taunekeneke ngā waikawa me ngā kawakore mā te tukanga whakawhiti pūrotene, ka mahi tētahi matū hei waikawa mā te tuku i te pūrotene, ā, ka mahi tētahi atu matū hei kawakore mā te tango i te pūrotene.
Ngā Tauira o ngā Tauhohenga Waikawa-Pūtake
Hei tauira o te tauhohenga māmā i waenga i te waikawa me te kawakore e ai ki te ariā Brønsted-Lowry ko te tauhohenga i waenga i te konupūmā parahi(II) (H2SO4) me te konutai hauwai (NaOH):
\[ \kuputuhi{H}_2\kuputuhi{SO}_4 + \kuputuhi{NaOH} \rightarrow \kuputuhi{NaHSO}_4 + \kuputuhi{H}_2\kuputuhi{O} \]
I tēnei tauhohenga, ka mahi te waikawa whanariki (H2SO4) hei waikawa Brønsted-Lowry nā te mea ka hoatu he pūtorino (H+) ki te pūtake NaOH, e tango ana i te pūtorino.
Ngā Tauira Pātai me ngā Kōrerorero
Pātai 1: Te Tāutu i ngā Waikawa me ngā Kawenga
Pātai:
Tāutuhia ngā waikawa me ngā kawakore Brønsted-Lowry i roto i ngā tauhohenga e whai ake nei:
\[ \kuputuhi{NH}_3 + \kuputuhi{H}_2\kuputuhi{O} \rightarrow \kuputuhi{NH}_4^+ + \kuputuhi{OH}^- \]
Kōrero:
I tēnei tauhohenga, ko te haukini (NH3) me te wai (H2O) ngā matū tauhohenga, ko ngā iona haukini (NH4+) me ngā iona hauwai (OH-) ngā hua. Kia kite tātou ko tēhea te mea e mahi ana hei waikawa, ko tēhea hoki te mea e mahi ana hei turanga.
– He turanga te NH3 nā te mea ka tangohia e ia ngā porotona (H+) mai i te H2O hei hanga i te NH4+.
– He waikawa te mahi a te H2O nā te mea ka tukuna he pūrotene (H+) ki te NH3 hei hanga i te OH-.
Nā, i roto i tēnei tauhohenga:
– He turanga Brønsted-Lowry a NH3.
– He waikawa Brønsted-Lowry te H2O.
Pātai 2: Te Tuhi i ngā Tauhohenga Hononga
Pātai:
Tuhia ngā takirua waikawa-pūtake honohono mō ngā tauhohenga e whai ake nei:
\[ \kuputuhi{HCl} + \kuputuhi{H}_2\kuputuhi{O} \rightarrow \kuputuhi{H}_3\kuputuhi{O}^+ + \kuputuhi{Cl}^- \]
Kōrero:
I tēnei tauhohenga, ka mahi a HCl hei waikawa Brønsted-Lowry mā te tuku i tētahi pūrotene (H+) ki te H2O. Ka tangohia e te wai (H2O) te pūrotene, ā, ka mahi hei turanga Brønsted-Lowry. I muri i te ngaronga o tētahi pūrotene, ka huri a HCl hei Cl-, ā, i muri i te whiwhi i tētahi pūrotene, ka huri a H2O hei H3O+.
– Te waikawa (HCl) me tōna turanga honohono (Cl-)
– Te turanga (H2O) me tōna waikawa honohono (H3O+)
Nō reira, ko te takirua waikawa-pūtake honohono i roto i tēnei tauhohenga ko:
– HCl / Cl-
– H2O / H3O+
Pātai 3: Te tatau i te pH o tētahi Waikawa Waikawa ngoikore
Pātai:
Tātaihia te pH o tētahi otinga 0.1 M o te waikawa acetic (CH3COOH) mēnā e mōhiotia ana ko te pūmau wehenga waikawa (Ka) ko \(1.8 \times 10^{-5}\).
Kōrero:
He waikawa ngoikore te waikawa acetic, ā, i roto i te wai ka whaka-ionitihia he wāhanga noa iho e ai ki te whārite e whai ake nei:
\[ \text{CH}_3\text{COOH} \rightleftharpoons \text{CH}_3\text{COO}^- + \text{H}^+ \]
Ko ngā mahi hei tatau i te pH koia ēnei:
1. Whakatūria te kīanga taurite mā te whakamahi i te kukū tīmatanga me te huringa o te kukū:
\[ \kuputuhi{Ka} = \frac{[\kuputuhi{CH}_3\kuputuhi{COO}^-][\kuputuhi{H}^+]}{[\kuputuhi{CH}_3\kuputuhi{COOH}]} \]
2. Whakakapia ngā uara e mōhiotia ana, ka whakaoti mō \([H^+]\):
\[ 1.8 \times 10^{-5} = \frac{x^2}{0.1 – x} \]
Nā te mea he iti rawa te \(x\) ki te 0.1, ka taea e tātou te whakatau tata i te \(0.1 – x \approx 0.1\):
\[ 1.8 \times 10^{-5} = \frac{x^2}{0.1} \]
\[ x^2 = 1.8 \whakareatia ki te 10^{-6} \]
\[ x = \sqrt{1.8 \times 10^{-6}} \]
\[ x \tata ki te 1.34 \whakareatia ki te 10^{-3} \]
3. Tātaihia te pH:
\[ \kuputuhi{pH} = -\log[\kuputuhi{H}^+] \]
\[ \text{pH} = -\log(1.34 \times 10^{-3}) \]
\[ \text{pH} \tata ki te 2.87 \]
Nō reira, ko te pH o te otinga waikawa M acetic 0.1 he tata ki te 2.87.
Pātai 4: Te Tāutu i ngā Otinga Amphiprotic
Pātai:
Tāutuhia te otinga amphiprotic i roto i te tauhohenga e whai ake nei, ā, whakamāramahia te take:
\[ \text{HCO}_3^- + \text{H}_2\text{O} \rightleftharpoons \text{H}_2\text{CO}_3 + \text{OH}^- \]
Kōrero:
Ko te otinga amphiprotic he otinga ka taea te mahi hei waikawa, hei turanga rānei, i runga i ngā āhuatanga o te tauhohenga. I roto i te tauira tauhohenga i runga ake nei:
– Ka mahi a \(\text{HCO}_3^-\) hei pūtake ina tangohia e ia he pūrotene mai i \(\text{H}_2\text{O}\), ka puta ko \(\text{H}_2\text{CO}_3\).
– Ka taea hoki e \(\text{HCO}_3^-\) te mahi hei waikawa i raro i ētahi atu āhuatanga, ka tukuna he pūrotene, ka puta ko \(\text{CO}_3^{2-}\).
E whakaatu ana tēnei he amphiprotic te katote \(\text{HCO}_3^-\). Ka taea e ia te mahi hei waikawa (kaituku proton) me te turanga (kaitango proton), i runga i te matū kē atu e tauhohe ana ki a ia.
Mā ēnei tauira raruraru, ka taea e tātou te mārama ake ki te whakamahinga o te ariā waikawa-pūtake Brønsted-Lowry hei tātari me te matapae i ngā taunekeneke matū. Ko te māramatanga pakari ki tēnei ariā te tūāpapa mō ngā tono maha i roto i te matū, te matū koiora, me ētahi atu pūtaiao.
