Ngā Tauira Pātai me te Kōrero mō ngā Ārani
He matū warowaihā māmā ngā ārikana, he hononga kotahi kei waenganui i ngā ngota waro me te hauwai. E mōhiotia ana hoki rātou ko ngā parafini, ā, he mekameka waro kua kūkū. Ko te āhuatanga matua o ngā ārikana ko tō rātou koretake, koia te take e whakamahia pinepine ai hei wahie me hei hinu whakahinuhinu. I roto i tēnei tuhinga, ka matapakihia e mātou ētahi tauira raruraru me ā rātou otinga e pā ana ki ngā ārikana.
He Kupu Whakataki ki ngā Ārani
Ka taea te whakaatu i ngā ārani mā te tātai whānui \(C_nH_{2n+2}\), ko \(n\) te maha o ngā ngota waro. Ko te ārani māmā rawa ko te methane (\(CH_4\)) me te ngota waro kotahi. Whai muri i tēnei ko te ethane (\(C_2H_6\)), te propane (\(C_3H_8\)), me ērā atu. Ko ngā ingoa o ngā ārani e whai ana i te ingoa IUPAC (International Union of Pure and Applied Chemistry) e whakamahi ana i te mutunga '-ane'.
Ngā Āhuatanga Ā-tinana o ngā Alkane
– Āhua ā-tinana: Ka nui ake ngā ngota waro i roto i te mekameka, ka teitei ake ngā ira rewa me ngā ira kohua. Hei tauira, ko te methane, te ethane, me te propane he hau i te pāmahana rūma, ko ngā alkane nui ake (hei tauira, te octane) he wai.
– Te wairewatanga: Kāore ngā ārani e wairewa ki te wai engari ka wairewa ki ētahi atu whakarewa kore-polar nā te mea he waikura kore rātou.
– Te Tauhohenga: He iti ake te tauhohenga o ngā ārani i ērā atu warowaihā nā te kaha o ō rātou hononga takitahi.
Ngā Tauhohenga Hira o ngā Alkane
– Te tahunga: Ka taea e ngā ārani te tahunga katoa ka puta he hauhā me te wai, ka taea rānei e te tahunga kāore i oti te tahunga ka puta he hauhā me te wai.
– Te Hārogenasi: Ka taea e ngā ārani te tauhohe ki ngā ārani (hei tauira, te haurore, te pūromine rānei) i raro i ētahi tikanga hei whakaputa i ngā ārani ārani.
Me titiro tātou ki ētahi tauira pātai me ā rātou matapakinga kia pai ake ai te mārama ki ngā ariā o runga ake nei.
Tauira Pātai 1: Te Whakaingoa i ngā Ārani
Pātai
Homai te ingoa IUPAC mō te matū e whai ake nei:
1. \( CH_3-CH_2-CH_3 \)
2. \( CH_3-CH_2-CH_2-CH_2-CH_3 \)
3. \( CH_3-CH_2-CH_2-CH_2-CH_3-CH_2-CH_3 \)
Kōrero
1. Ko te matū me te tātai \( CH_3-CH_2-CH_3 \) ko te propane. Ko te ingoa IUPAC mō tēnei matū ko te propane.
2. Ko te matū me te tātai \( CH_3-CH_2-CH_2-CH_2-CH_3 \) ko te pentane. Ko te ingoa IUPAC mō tēnei matū ko te Pentane.
3. Ko te matū me te tātai \( CH_3-CH_2-CH_2-CH_2-CH_3-CH_2-CH_3 \) ko te heptane. Ko te ingoa IUPAC mō tēnei matū ko te Heptane.
Whakamārama
I te wā e whakaingoa ana i ngā alkana, e rua ngā ture matua ka taea te whai:
1. Tāutuhia te mekameka waro roa rawa hei mekameka matua.
2. Whakaingoatia kia rite ki te maha o ngā ngota waro i roto i te mekameka (met-, et-, prop-, but-, me ētahi atu), ā, whai muri ko te tāpiritanga -ane.
Tauira Pātai 2: Ngā Isomera
Pātai
Tuhia, ka whakaingoatia hoki ngā hanganga isomeric mō te butane (\(C_4H_{10}\)).
Kōrero
E rua ngā isomers hanganga o te pūtāne:
1. n-Pūtāne:
Hanganga: \( CH_3-CH_2-CH_2-CH_3 \)
Ingoa IUPAC: n-Pūtāne
2. Isobutane (Methylpropane):
Hanganga:
""
CH3
|
CH3-C-CH3
|
H
""
Ingoa IUPAC: 2-Methylpropane
Whakamārama
Ko ngā isomers he pūhui he rite te tātai ngota engari he rerekē ngā hanganga. Mō te butane (\(C_4H_{10}\)), e rua ā tātou hanganga pea:
– He mekameka waro tika tō te n-Pūtāne.
– He peka (methyl) tō te isobutane i te waro tuarua.
Tauira Pātai 3: Te tahunga o ngā ārani
Pātai
Tuhia ngā tauhohenga tahunga katoa me ngā tauhohenga tahunga kāore anō kia oti mō te propane (\(C_3H_8\)).
Kōrero
1. Te tahunga tino tika:
Tauhohenga: \( C_3H_8 + 5O_2 \rightarrow 3CO_2 + 4H_2O \)
2. Te tahunga kore i oti:
– Ka whakaputa i te hauhā waro:
Tauhohenga: \( C_3H_8 + 3.5O_2 \rightarrow 3CO + 4H_2O \)
– Ka whakaputa i te waro totoka (ngā pungarehu):
Tauhohenga: \( C_3H_8 + 2O_2 \rightarrow 3C + 4H_2O \)
Whakamārama
I te tahunga katoa, ka tauhohe ngā ārani ki te hāora e ranea ana hei whakaputa i te hauhā me te wai. Nā te kore o te hāora, ka puta te hauhā monoki, te waro totoka rānei, nā te tahunga kore e oti.
Tauira Pātai 4: Ngā Tauhohenga Whakakapinga i roto i ngā Alkane
Pātai
Tuhia te whārite tauhohenga mō te whakahāoratanga o te methane ki te chlorine, ka whakaingoa i te hua.
Kōrero
Tauhohenga whakakapinga mō te methane ki te chlorine:
\[ CH_4 + Cl_2 \rightarrow CH_3Cl + HCl \] (i te aroaro o te mārama UV)
Ko ngā hua ka puta ko te methyl chloride (\(CH_3Cl\)) me te waikawa hydrochloric (\(HCl\)).
Whakamārama
Ko te halogenation he tauhohenga e whakakapia ai tētahi, neke atu rānei ngā ngota hauwai i roto i tētahi alkane e ngā ngota halogen. I tēnei wā, ka tauhohe te methane ki te chlorine, ka whakakapia tētahi ngota hauwai e tētahi ngota chlorine, ā, ka hiahiatia te mārama UV hei whakakorikori.
Tauira Pātai 5: Ngā Tātai Whakamātautau me ngā Tātai Ngota
Pātai
Ki te hoatu he pūhui ā-waikawa he 82,76% te hanganga o te waro me te 17,24% te hauwai, whakatauhia ngā tātai whaimana me ngā tātai ngota mō te ā-waikawa mēnā ko tōna papatipu molar he 58 g/mol.
Kōrero
1. Tātaihia ngā mole o ia huānga i runga i te papatipu ngota.
– C: \( \left(\frac{82,76}{12}\right) = 6,896 \)
– H: \( \left(\frac{17,24}{1}\right) = 17,24 \)
2. Whakaōritea te whakataurite hei whakangawari:
– Te ōwehenga tino: \( \left(\frac{6,896}{6,896}\right) = 1 \)
– Te ōwehenga H/C: \( \left(\frac{17,24}{6,896}\right) = 2,5 \)
3. Whakarerekētia te ōwehenga: \[ C_{2}\left(\frac{2,5 \cdot (2)}{2}\right)H_{5} = C_{4}H_{10}\]
4. He rite te tātai ā-ira ki te ārani (58 g/mol).
Whakamārama
Mā te whai i ēnei kaupae, ka whiwhi tātou i ngā tātai ā-wheako me ngā tātai ngota ngota o ngā ārani kua whakatauritea i runga i ngā papatipu ngota whanaunga me te taurite papatipu whānui.
Whakamutunga
He mea nui te mārama ki ngā ārani i roto i te matū waro taketake. Mā roto i ngā tauira me ngā kōrero maha, kua hipokina e mātou te whakaingoa i ngā ārani, te mārama ki te isomerism, ngā tauhohenga mura, te whakakapinga, me te whakatau i ngā tātai empirical me ngā tātai ngota o ngā ārani. Mā te mārama ki ēnei ariā ka āwhina koe ki te whakarite mō ngā tono me ngā wero e pā ana ki ngā warowaihā kua kōtui i roto i te oranga o ia rā me te ahumahi.
