Ngā Tauira Pātai me te Kōrero mō ngā Pūtau Hikohiko
He taputapu te pūtau hikohiko e whakamahia ana hei huri i te pūngao hiko hei tauhohenga matū kore-tūturu, he rerekē ki te pūtau hikohiko, ki te pūtau karawaka rānei, e huri ana i te pūngao matū hei pūngao hiko. I roto i te pūtau hikohiko, ka whakamahia he iahiko hiko hei akiaki i tētahi tauhohenga matū e kore e puta me te kore he pūngao hiko tāpiri. He mea nui tēnei ariā i roto i ngā tono ahumahi maha pērā i te hanga konganuku parakore, te hikohiko o te wai hei whakaputa hauwai me te hāora, me te maha atu.
Ka matapakihia e tēnei tuhinga ētahi tauira o ngā raruraru hikohiko me ērā atu matapakinga hei āwhina i ngā ākonga ki te mārama ake ki te ariā o ngā pūtau hikohiko.
Tauira Pātai 1: Te Whakamahinga Hiko o te Wairewa NaCl
Ngā Whakautu
Ka whakapūkaratia he wairewa konutai pūhaumāota (NaCl) mā te whakamahi i ngā irahiko kore mahi. Tuhia ngā tauhohenga e puta ana i te katote me te anote me ngā hua i hangaia i ia irahiko.
Kōrero
I roto i te pūtau hikohiko, e rua ngā hikohiko: te katote (hikohiko kino) me te anote (hikohiko pai). Ka puta te hikohiko o te otinga NaCl i ngā wāhanga e rua: te tauhohenga i te katote me te tauhohenga i te anote.
1. Tauhohenga i te Cathode:
I te katote, ko ngā katote e whai wāhi ana ko ngā katote Na^+ me ngā katote H_2O. Heoi, he māmā ake te whakaiti i ngā katote H_2O i ngā katote Na^+ nā te mea he nui ake tō rātou pūmanawa whakaiti.
Ko te tauhohenga e puta ana i te katote ko:
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2H₂O(l) + 2e⁻ → H₂(g) + 2OH⁻(aq) (Pūmanawa whakaiti = -0.83 V)
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Ko te hua e puta mai ana i te katote he hau hauwai (H₂).
2. Tauhohenga i te Anode:
I te anode, ko ngā katote e whai wāhi ana ko ngā katote Cl⁻ me ngā katote H_2O. He māmā ake te waikura o ngā katote Cl⁻ i ngā katote H_2O nā te iti o tō rātou pūmanawa waikura.
Ko te tauhohenga e puta ana i te anode ko:
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2Cl⁻(aq) → Cl₂(g) + 2e⁻ (Pūmanawa waikura = -1.36 V)
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Ko te hua e puta mai ana i te anode he hau chlorine (Cl₂).
Nō reira, i roto i te electrolysis o te otinga NaCl, ko te hua e puta ana i te cathode he hau hauwai (H₂) ā, i te anode he hau chlorine (Cl₂).
Tauira Pātai 2: Te Whakakorikori i te Wairewa CuSO₄ me ngā Irahiko Parahi
Ngā Whakautu
I whakahaerehia te hikohiko o te otinga parahi(II) whanariki (CuSO₄) mā te whakamahi i ngā irahiko parahi. Tuhia ngā tauhohenga e puta ana i te katote me te anote me ngā hua i hangaia i ia irahiko.
Kōrero
I tēnei wā, ehara te hiko i te hiko kore mahi, engari he hiko parahi, nō reira ka tauhohe te hiko.
1. Tauhohenga i te Cathode:
I te katote, ka whakaitihia ngā iona Cu²⁺ i te anode.
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Cu²⁺(aq) + 2e⁻ → (ngā) Cu (Pūmanawa whakaheke = +0.34 V)
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Ko te hua e puta mai ana i te katote he parahi totoka (Cu) ka whakatakotoria ki runga i te irahiko.
2. Tauhohenga i te Anode:
I te anode, ka waikuratia te hiko parahi.
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(ng) Cu → Cu²⁺(aq) + 2e⁻ (Pūmanawa hāora = -0.34 V)
""
Ko te hua e puta mai ana i te anode he iona Cu²⁺.
Nā te mea he parahi te irahiko, ka whakaea ngā katote Cu²⁺ i whakapūngaohia i roto i te wairewa mā te whakarewanga o te parahi i te irahiko anode.
Tauira 3: Te Papatipu o te Konganuku i Whakatakotoria
Ngā Whakautu
I roto i tētahi pūtau hikohiko, e rere ana te 0.2 mol o ngā irahiko mā roto i tētahi otinga CuSO₄. E hia karamu o te parahi e whakatakotoria ana ki te katote?
Kōrero
Ka taea te whakamahi i te maha o ngā mole o ngā irahiko (F) e rere ana hei whakatau i te maha o ngā mole o te konganuku kua whakatakotoria. Ko te whārite a Faraday mō te whakatakotoranga konganuku ko:
\[ n = \frac{Q}{Fz} \]
kāore i te mana:
– Q = te nui o te utu (i roto i ngā Coulomb)
– F = te pūmau o Faraday (96500 C/mol)
– z = te maha o ngā irahiko mō ia mole o te tauhohenga.
I tēnei wā, ka mimitihia e Cu²⁺ ngā irahiko e rua hei Cu, nō reira ko z = 2.
Ko te maha o ngā mole parahi i whakatakotoria ko:
\[ n = \frac{0.2 \text{ ngā irahiko}}{2} = 0.1 \text{ ngā irahiko Cu} \]
Taumaha o te parahi i whakatakotoria:
\[ \text{papatipu o Cu} = n \times \text{Mr} \]
ko Mr te papatipu molar o Cu (63.5 g/mol)
Nā reira:
\[ \text{papatipu o Cu} = 0.1 \times 63.5 = 6.35 \text{ karamu} \]
Nō reira, ka whakatakotoria te 6.35 karamu o te parahi ki runga i te katote.
Tauira Pātai 4: Te Whakakorikori i te Wairewa KI
Ngā Whakautu
Ka whakamahia ngā irahiko kore mahi hei whakahaere i te whakapūngao hiko o tētahi otinga KI. Tuhia ngā tauhohenga e puta ana i te katote me te anote me ngā hua ka puta i ia irahiko.
Kōrero
1. Tauhohenga i te Cathode:
I te katote, ko ngā katote e whai wāhi ana ko ngā katote K⁺ me ngā katote H_2O. He māmā ake te whakaiti i te H_2O i ngā katote K⁺.
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2H₂O(l) + 2e⁻ → H₂(g) + 2OH⁻(aq)
""
Ko te hua e puta mai ana i te katote he hau hauwai (H₂).
2. Tauhohenga i te Anode:
I te anode, ko ngā katote e whai wāhi ana ko ngā katote I⁻ me ngā katote H_2O. He māmā ake te waikura o ngā katote I⁻ i ngā katote H_2O.
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2I⁻(aq) → I₂(s) + 2e⁻
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Ko te hua e puta mai ana i te anode ko te iodine (I₂).
Nō reira, i roto i te electrolysis o te otinga KI, ko te hua e puta mai ana i te cathode ko te hau hauwai (H₂) ā, i te anode ko te iodine (I₂).
Te Katinga
He mea nui te māramatanga pakari ki ngā mātāpono me ngā whakamahinga o ngā pūtau hikohiko mō ngā ākonga matū me ngā tohunga ngaio i roto i ngā mara pēnei i te whakarewa, te whakaputa matū, me te umanga pūngao. Kei roto i tēnei tuhinga ētahi tauira rapanga hikohiko me ā rātou otinga hei āwhina i te whakapakari i tēnei māramatanga. Ko te tumanako mā te mōhio ki ēnei ariā taketake ka āwhina i te whakaoti rapanga mahi me ngā rapanga ariā e tūpono ana ki te ao tūturu.
