Ngā Tauira Pātai e Matapaki ana i te Waikura me te Whakaiti
Pendahuluan
He ariā matua te waikura me te whakaiti i roto i te matū, e hono tahi ana, e kore e taea te wehe. Ka puta ngātahi ēnei tukanga i roto i tētahi tauhohenga e mōhiotia ana ko te tauhohenga redox (tauhohenga waikura-whakaiti). I roto i tēnei tauhohenga, ka tukuna e te matū e waikuratia ana ngā irahiko, ko te matū e whakaititia ana ka whiwhi irahiko. Hei mārama ake, me titiro tātou ki tētahi tauira raruraru me tōna whakamārama.
Ngā Pātai me te Kōrero mō te Waikura me te Whakaiti
Tauira Pātai 1
Pātai:
Tāutuhia ngā matū ka pāngia e te waikura me te whakaiti i roto i te tauhohenga e whai ake nei:
\[ 2Mg(s) + O_2(g) \rightarrow 2MgO(s) \]
Kōrero:
Hei whakatau ko ēhea matū ka pāngia e te waikura me te whakaiti, me tirotiro tātou i te huringa o te tau waikura o ia huānga i roto i te tauhohenga.
1. Ngā tau waikura i roto i te pūhui tuatahi:
– He huānga kore utu te konupūmā (Mg) i roto i te āhua totoka (s), nō reira ko tōna tau waikura he 0.
– He huānga kore utu te hāora (O₂) i roto i te āhua o ngā ngota hau (g), nō reira ko tōna tau waikura he 0 anō hoki.
2. Ngā tau waikura i roto i ngā pūhui hua:
– Ko te tau whakapūngao o te konupūmā i roto i te konupūmā waikura (MgO) he +2 (Mg²⁺).
– Ko te tau whakapōrearea o te hāora i roto i te konupora waikura (MgO) he -2 (O²⁻).
3. Ngā panonitanga o te tau waikura:
– Ka huri te konupūmā mai i te 0 ki te +2. Ko te tikanga tēnei kua piki ake te tau waikura o te konupūmā, kua waikuratia rānei.
– Ka huri te hāora mai i te 0 ki te -2. Ko te tikanga tēnei kua heke te tau waikura o te hāora, kua whakaitihia rānei.
Ngā tauira:
– He matū te konupūmā (Mg) ka waikuratia.
– Ko te hāora (O₂) he matū ka whakaitihia.
Tauira Pātai 2
Pātai:
Tāutuhia te ākena whakahāora me te ākena whakaiti i roto i te tauhohenga e whai ake nei:
\[ Zn + CuSO_4 \perematau ZnSO_4 + Cu \]
Kōrero:
I tēnei tauhohenga, ka whakatauhia ko wai ka waikurahia, ko wai hoki ka whakaitihia, ā, ka tautuhia hoki te ākena waikura me te ākena whakaiti.
1. Ngā matū tauhohe:
– Zn (s) : Tau waikura = 0.
– Cu i roto i te CuSO₄ : Tau hāora = +2.
2. Ngā Hua:
– Zn i roto i te ZnSO₄: Tau waikura = +2.
– Cu (s) : Tau waikura = 0.
3. Ngā Huringa o ngā Tau Waikura:
– Ka huri te Zn mai i te 0 ki te +2. Ko te tikanga tēnei ka piki ake te tau waikura o te Zn, ka waikuratia rānei.
– Ka huri te Cu mai i te +2 ki te 0. Ko te tikanga tēnei ka heke te tau waikura o te Cu, ka pāngia rānei e te whakaiti.
4. Ngā Āhua Whakahāora me ngā Āhua Whakaiti:
– Ko te matū whakahāngai he matū e whakahāngai ana i tētahi atu matū, ā, ka whakaitihia anō hoki. I roto i tēnei tauhohenga, ka whakahāngai a Cu²⁺ i roto i te CuSO₄ i te Zn, nō reira ko Cu²⁺ te matū whakahāngai.
– Ko te matū whakaiti he matū e whakaiti ana i tētahi atu matū, ā, ka waikuratia anō hoki. I roto i tēnei tauhohenga, ka whakaitihia te Cu²⁺ e te Zn, nō reira he matū whakaiti te Zn.
Ngā tauira:
– Ko te matū whakahāora ko Cu²⁺ i roto i te CuSO₄.
– Ko te matū whakaiti ko Zn.
Tauira Pātai 3
Pātai:
Tātaihia ngā tau waikura o ngā huānga o ngā matū e whai ake nei:
\[ H_2SO_4 \]
Kōrero:
Hei whakatau i te tau waikura o ia huānga i roto i te waikawa whanariki (H₂SO₄), ka whakamahia e mātou ngā ture mō te whakatau i ngā tau waikura.
1. Ko te tau waikura o te hauwai (H) i roto i ngā pūhui he +1 te tikanga.
2. Ko te tau waikura o te hāora (O) i roto i ngā matū he -2 te tikanga.
3. Me 0 te tapeke o ngā tau waikura i roto i tētahi matū kūpapa.
Inaianei ka tatauhia e mātou:
– Hauwai: 2 ngā ngota H ia +1, tapeke (+1) 2 = +2.
– Hāora: 4 ngā ngota O ia -2, tapeke (-2) 4 = -8.
– Whānariki: Me kī ko te tau waikura S = x.
Te tapeke o ngā tau waikura:
\[ 2(+1) + x + 4(-2) = 0 \]
\[ 2 + x – 8 = 0 \]
\[ x – 6 = 0 \]
\[ x = +6 \]
Ngā tauira:
– Tau waikura H = +1
– Tau waikura O = -2
– Tau waikura S = +6
Tauira Pātai 4
Pātai:
I te tauhohenga e whai ake nei, tautuhia te tau waikura o ia huānga, ā, tautuhia te haurua-tauhohenga o tēnei tauhohenga redox:
\[ MnO_4^- + 8H^+ + 5Fe^{2+} \pere matau Mn^{2+} + 4H_2O + 5Fe^{3+} \]
Kōrero:
1. Whakatauhia te tau waikura:
– Mn i roto i te MnO₄⁻ : Ko te tau whakapūngao o te Mn he +7. (Nā te mea ko te O = -2 i roto i ngā ngota O e 4: (-2) 4 = -8; Ko te katote ōrite o te MnO₄⁻ = -1; Nō reira me +7 te Mn mō te taurite: +7 – 8 = -1).
– Fe i roto i te Fe²⁺ : Ko te tau waikura o Fe he +2.
– Mn i roto i te Mn²⁺ : Ko te tau waikura o te Mn he +2.
– Fe i roto i te Fe³⁺: Ko te tau waikura o Fe he +3.
– Te hāora i roto i te H₂O: Ko te tau waikura o te O he -2.
– Te hauwai i roto i te H₂O: Ko te tau waikura o te H he +1.
2. Whakatauhia te haurua o te tauhohenga:
– Te tauhohenga waikura (ka huri te Fe²⁺ hei Fe³⁺):
\[ Fe^{2+} \rightarrow Fe^{3+} + e^- \]
– Tauhohenga whakaiti (MnO₄⁻ ki Mn²⁺):
\[ MnO_4^- + 8H^+ + 5e^- \perematau Mn^{2+} + 4H_2O \]
Ngā tauira:
– Ko te tau whakapūngao o te Mn i roto i te MnO₄⁻ he +7.
– Ko te tau waikura o Fe i roto i te Fe²⁺ he +2.
– Ko te tau waikura o Fe i roto i te Fe³⁺ he +3.
Te Katinga
Mā te mārama ki ngā tauira me ā rātou matapakinga, ka māmā ake te mārama ki ngā ariā o te waikura me te whakaiti i roto i te matū. He mea nui te mahi a ngā tau waikura ki te whakatau ko ēhea ngā matū ka waikurahia, ko ēhea hoki ka whakaitihia i roto i ngā tauhohenga matū. Ko te tumanako, ka āwhina tēnei tuhinga i a koe ki te mārama ake me te matatau ki ngā ariā o te waikura me te whakaiti.
