Me pēhea te whakatau i ngā tau waikura
He ariā nui te mārama ki ngā tau waikura (ngā āhua waikura rānei) i roto i te matū e āwhina ana i a tātou ki te mārama ki ngā tauhohenga matū, inā koa ngā tauhohenga redox. Ko te tau waikura te maha o ngā irahiko me tāpiri, me tango rānei i tētahi ngota hei huri i tōna āhua taketake. I roto i tēnei tuhinga, ka tūhuratia hohonutia e tātou me pēhea te whakatau i te tau waikura o tētahi huānga i roto i tētahi matū matū.
Ngā Kaupapa Taketake o te Tau Waikura
Ka taea te whakaaro ko ngā tau waikura he taputapu tatau ōkawa e whakaahua ana i te tohatoha o ngā irahiko i roto i tētahi ngota, i tētahi katote rānei. Ahakoa kāore ngā tau waikura e tohu tonu i te utu hiko tuturu o ngā ngota i roto i te ngota, ka māmā ake te tukanga tātari matū.
Ko ētahi ture matua mō te whakatau i ngā tau waikura koia ēnei:
1. Ko te tau waikura o tētahi huānga i te āhua o tētahi ngota huānga (homonuclear) he kore tonu. Hei tauira:
– O₂ (hauora) -> Ko tōna tau waikura he 0
– N₂ (dinitrogen) -> Ko tōna tau waikura he 0
2. He ōrite te tau waikura mō te katote monatomic ki te utunga o te katote.
– Na⁺ -> Ko tōna tau waikura he +1
– Cl⁻ -> Ko tōna tau waikura he -1
3. Ko te tau whakapūngao o te hauwai he +1 ina honoa ki tētahi mea ehara i te mea whakarewa, ā, he -1 ina honoa ki tētahi mea whakarewa i roto i tētahi hauwai. Hei tauira:
– H₂O -> Ko te tau waikura o te hauwai he +1
– NaH -> Ko te tau waikura o te hauwai he -1
4. Ko te tau waikura o te hāora he -2 i te nuinga o ngā pūhui, engari he rerekētanga anō hoki pērā i ngā peroxide he -1 te tau waikura o te hāora.
– H₂O -> Ko te tau waikura o te hāora he -2
– H₂O₂ (hauwai waikura) -> Ko te tau waikura o te hāora he -1
5. Ko te tau whakapūngao o ngā halogens (F, Cl, Br, I) i roto i ngā pūhui he -1 te tikanga, engari i te wā e honoa ana ki te hāora, ki ētahi atu halogens rānei, ka rerekē pea.
Ngā Hipanga hei Whakatau i ngā Tau Waikura
Hei whakatau i te tau waikura o tētahi huānga i roto i tētahi pūhui, ka taea e tātou te whai i ēnei mahi:
Hipanga 1: Tuhia te Hanganga/Tātai Ngota o te Matū
Tīmata mā te tuhi i te hanganga ngota ngota, te tātai rānei o te matū. Hei tauira, mō te H₂SO₄ (waikawa whanariki).
Hipanga 2: Whakatauhia te Tau Waikura o ngā Huānga i runga i ngā Ture
– Mō te H₂SO₄, e mōhio ana tātou he +1 tonu te tau waikura o te hauwai, ā, he -2 tonu te tau waikura o te hāora.
– Hauwai (H): +1 (2 ngā ngota H, +2 katoa)
– Hāora (O): -2 (4 ngota O, -8 katoa)
Hipanga 3: Whakatauhia te Tau Waikura o te Huānga Kāore i te Mōhiotia
Mena kei te hiahia kia tino kūpapa te pūhui, kia hanga rānei i ngā katote, me whakarite kia kore te uara katoa o te tau waikura mō ngā pūhui kūpapa, kia rite rānei ki te utu katote mō ngā katote.
– He matū koretake te waikawa whanariki (H₂SO₄). Nō reira, me kore te tapeke o ngā āhua waikura.
– Kei a tātou ngā tau waikura mō te H (+1) me te O (-2), nō reira, hei kimi i te tau waikura o te whanariki (S), ka whakamahia e tātou te whārite:
\[
2(+1) + S + 4(-2) = 0
\]
\[
2 + S – 8 = 0
\]
\[
S – 6 = 0
\]
\[
S = +6
\]
Nō reira, ko te tau waikura mō te whanariki i roto i te H₂SO₄ he +6.
Hipanga 4: Manatoko
Manatokohia ko te tapeke o ngā tau waikura he ōrite ki te 0 mō ngā ngota kūpapa, he rite rānei ki te utu ionic mēnā kei te mahi tātou me ngā ions.
He Tauira Anō mō te Whakatau i ngā Tau Waikura
Tauira 1: Pāhare pākawa waro (KMnO₄)
Mō tēnei matū ka whai mātou i ngā ture o runga ake nei:
– Pāhare pākawa (K): I te nuinga o te wā +1
– Hāora (O): -2
E mōhio ana tātou he kūpapa tēnei ngota ngota, ā, ko te hua o tēnei whārite:
\[
1(+1) + Mn + 4(-2) = 0
\]
\[
1 + Mn – 8 = 0
\]
\[
Mn – 7 = 0
\]
\[
Mn = +7
\]
Nō reira, ko te tau whakapūngao o te Mn i roto i te KMnO₄ he +7.
Tauira 2: Haukiniuma Nitrate (NH₄NO₃)
E rua ngā wāhanga mō tēnei matū: NH₄⁺ me NO₃⁻.
– NH₄⁺:
– Hauwai (H): +1
– Nō reira, mō te hauota (N) i roto i te NH₄⁺:
\[
N + 4(+1) = +1
\]
\[
N + 4 = +1
\]
\[
N = -3
\]
– KĀORE₃⁻:
– Hāora (O): -2
– Hauota (N) i roto i te NO₃⁻:
\[
N + 3(-2) = -1
\]
\[
N – 6 = -1
\]
\[
N = +5
\]
Ētahi Tūnga me ngā Take Motuhake
He mea motuhake ēnei ki te ture whānui hei maumahara:
1. Te Hāora i roto i te Peroxide:
– I roto i te H₂O₂, i te Na₂O₂ rānei, ko te tau waikura o te hāora he -1, ehara i te -2.
2. Ngā Huānga me ngā Tau Waikura Maha:
– He rerekē te tau waikura o ngā huānga pērā i te whākōkī (P), te whanariki (S), me ngā konganuku whakawhiti i roto i ngā pūhui rerekē. Hei tauira, ka taea e te rino (Fe) te whai tau waikura o te +2, +3 rānei.
3. He +2 tonu ngā konganuku kawakore o te whenua, ā, he +1 tonu ngā konganuku kawakore.
Whakamutunga
He pūkenga taketake, he pūkenga nui hoki te whakatau i ngā tau waikura i roto i te matū, inā koa mō te mārama ki ngā tauhohenga redox me ngā momo tauhohenga matū rerekē. Mā te whai i ngā ture me ngā mahi i runga ake nei, ka taea e koe te whakatau tika i ngā tau waikura i roto i ngā momo matū. Whakaharatauhia te whakatau i ngā tau waikura me ngā tauira rerekē o ngā matū hei whakapakari i tō māramatanga.
