Tauira o ngā Pātai Kōrero mō ngā Irahiko
Ko ngā irahiko he matū ka taea te kawe hiko ina rewa ki te wai, ki ētahi atu whakarewa rānei. E rua ngā momo matua o ngā irahiko: ko ngā irahiko kaha me ngā irahiko ngoikore. Ka whaka-ioniti katoatia ngā irahiko kaha i roto i te otinga, ko ngā irahiko ngoikore ia ka whaka-ioniti wāhanga noa iho. He mahi nui tā ngā irahiko i roto i ngā tauhohenga matū me te oranga o ia rā. I roto i tēnei tuhinga, ka matapakihia e mātou ētahi tauira raruraru me ō rātou whakamārama e pā ana ki ngā irahiko.
Tauira Pātai 1: Te Whakatau i te Taumata o te Ionization
Pātai: E mōhiotia ana ko te kukū o te waikawa acetic (CH₃COOH) he 0,1 M, ā, ko te nekehanga o te ionization (α) he 4%. He aha te kukū o ngā ion i roto i te otinga?
Kōrero:
1. Whakatauhia te taumata o te ionization:
Ko te nui o te ionization (α) ko te ōwehenga o tētahi matū kua ionized i roto i te wairewa. I te mea ko α = 4% = 0.04.
2. Whārite ionization o te waikawa acetic:
\[
\text{CH}_3\text{COOH} \rightleftharpoons \text{CH}_3\text{COO}^- + \text{H}^+
\]
3. Te tatau i te kukū:
Ko te kukū tīmatanga o te CH₃COOH he 0,1 M. Nā te mea ko te nekehanga o te ionization he 0,04, kāti:
\[
[\text{CH}_3\text{COO}^-] = [\text{H}^+] = 0.1 \times 0.04 = 0.004 \text{ M}
\]
Te kukū o te CH₃COOH kāore i te ionized:
\[
[\kāhua{CH}_3\kāhua{COOH}] = 0.1 \kāhua{ M} – 0.004 \kāhua{ M} = 0.096 \kāhua{ M}
\]
Whakautu:
\[
[\text{CH}_3\text{COO}^-] = 0.004 \text{ M}
[\kāhua{H}^+] = 0.004 \kāhua{ M}
[\text{CH}_3\text{COOH}] kāore i te whaka-katote = 0.096 \text{ M}
\]
Tauira Pātai 2: Te Tatau i te Ksp (Hua Wairewa)
Pātai: Ki te hoatu he tote, ko BaSO₄, he wairewa pakupaku ki te wai, ā, ko tōna wairewatanga he 1,0 × 10⁻⁵ M. Tātaihia te Ksp o BaSO₄.
Kōrero:
1. Te whārite wairewa mō te tote BaSO₄:
\[
\text{BaSO}_4 (s) \rightleftharpoons \text{Ba}^{2+} (aq) + \text{SO}_4^{2-} (aq)
\]
2. Te wairewatanga:
I te mea ko te wairewatanga o BaSO₄ = 1,0 × 10⁻⁵ M.
3. Tātaihia te kukū katote:
Mena ko te wairewatanga o BaSO₄ = s = 1,0 × 10⁻⁵ M, kāti:
\[
[\text{Ba}^{2+}] = 1,0 \times 10^{-5} \text{ M}
\]
\[
[\text{SO}_4^{2-}] = 1,0 \times 10^{-5} \text{ M}
\]
4. Te tatau i te Ksp:
\[
K_{sp} = [\text{Ba}^{2+}] \times [\text{SO}_4^{2-}]
\]
\[
K_{sp} = (1,0 \times 10^{-5}) \times (1,0 \times 10^{-5})
\]
\[
K_{sp} = 1,0 \times 10^{-10}
\]
Whakautu:
\[
K_{sp} \text{ BaSO₄} = 1,0 \times 10^{-10}
\]
Tauira Pātai 3: pH o ngā Waikawa me ngā Waikawa Tuturu
Pātai: Tātaihia te pH o tētahi otinga HCl he 0,01 M te kukū.
Kōrero:
1. Whārite whakakāonga o te HCl:
\[
\kāhua{HCl} \rightarrow \kāhua{H}^+ + \kāhua{Cl}^-
\]
He waikawa kaha te HCl, nō reira kua oti te ionization.
2. Tātaihia te kukū o te hauwai ion:
Ko te kukū HCl = 0,01 M te tikanga:
\[
[\kāhua{H}^+] = 0.01 \kāhua{ M}
\]
3. Te tatau i te pH:
\[
\kāhua{pH} = -\log[\kāhua{H}^+]
\]
\[
\kāhua{pH} = -\log(0.01)
\]
\[
pH = 2
\]
Whakautu:
\[
\text{pH} \text{ Wairewa HCl} = 2
\]
Tauira Pātai 4: Te tatau i te pOH o tētahi Otinga Pūtake
Pātai: Tātaihia te pOH me te pH o tētahi otinga KOH he 0,001 M te kukū.
Kōrero:
1. Whārite whakakāonga o KOH:
\[
\kāhua{KOH} \rightarrow \kāhua{K}^+ + \kāhua{OH}^-
\]
He turanga kaha a KOH, nō reira kua oti te ionization.
2. Tātaihia te kukū o ngā katote hauwai:
Ko te kukū KOH = 0,001 M te tikanga:
\[
[\kākau{OH}^-] = 0.001 \kākau{ M}
\]
3. Te tatau i te pOH:
\[
\kāhua{pOH} = -\log[\kāhua{OH}^-]
\]
\[
\kāhua{pOH} = -\log(0.001)
\]
\[
\kāhua{pOH} = 3
\]
4. Te tatau i te pH:
\[
pH = 14 – pOH
\]
\[
pH = 14 – 3
\]
\[
pH = 11
\]
Whakautu:
\[
\text{pOH} \text{ otinga KOH} = 3
\text{pH} \text{ wairewa KOH} = 11
\]
Tauira Pātai 5: Te Whakatau i te Kukū o ngā Iona Hauwai
Pātai: Ko te pH o te wairewa waikawa hauwai (HF) he 3. He aha te kukū o ngā katote hauwai (OH⁻) i roto i te wairewa?
Kōrero:
1. Whakatauhia te kukū o ngā iona hauwai:
Ki te mea ko te pH = 3, kāti:
\[
[\kāhua{H}^+] = 10^{-3} \kāhua{ M}
\]
2. Mā te whakamahi i te ariā o te whanaungatanga i waenga i te pH me te pOH:
\[
pH + pOH = 14
\]
3. Te tatau i te pOH:
\[
\kāhua{pOH} = 14 – \kāhua{pH}
\]
\[
\kāhua{pOH} = 14 – 3 = 11
\]
4. Tātaihia te kukū o ngā katote hauwai:
\[
[\kākau{OH}^-] = 10^{-\kākau{pOH}}
\]
\[
[\kāhua{OH}^-] = 10^{-11} \kāhua{ M}
\]
Whakautu:
\[
[\text{OH}^-] \text{ i roto i te otinga HF} = 1 \times 10^{-11} \text{ M}
\]
Whakamutunga
He mea nui te mārama ki ngā ariā taketake o ngā irahiko me te wairewatanga i roto i te matū. Mā te mōhio ki te tatau i te taumata o te ionization, Ksp, pH, me te pOH, ka taea e tātou te whakaoti rapanga maha e pā ana ki ngā otinga irahiko. Kua matapakihia e tēnei tuhinga ētahi tauira rapanga me ā rātou otinga hei whakarato i tētahi māramatanga mārama mō te whakaoti rapanga e pā ana ki te irahiko. Ko te tumanako, he āwhina tēnei whakamārama mō ngā kaipānui e hiahia ana ki te whakawhānui ake i ō rātou mōhiotanga ki ngā irahiko i roto i te matū.
