Ama-mole, isisindo se-molar nenombolo ka-Avogadro

Ukubala izinhlayiya ngokuzikala

Ama-athomu amancane kakhulu ukuthi angabalwa ngamunye ngamunye, ngakho osokhemisi bawabala ngamaqoqo amisiwe, njengoba isitolo sibala amaqanda ngedazini. Iqoqo yi-mole. Kusukela ekubuyekezweni kwe-SI kwango-2019, i-mole eyodwa iqukethe ngqo izinhlangano ezishiwo ezingu-6.02214076 × 10²³, futhi isilinganiso esingaguquki sika-Avogadro sichazwa ngqo ngokuthi 6.02214076 × 10²³ mol⁻¹. Ezibalweni, u-6.022 × 10²³ mol⁻¹ uvame ukwanela.

Inhlangano kumele ihlale ishiwo. I-mole yama-athomu e-oxygen (O) ne-mole yamamolekyuli e-oxygen (O₂) aqukethe inani elilinganayo lezinhlangano, kodwa eyesibili iqukethe ama-athomu aphindwe kabili futhi inesisindo esiphindwe kabili. Ukubhala ifomula eduze kwenani ngalinye, njengo-0.50 mol O₂, kuvimbela ukudideka okuningi abafundi abahlangana nako ngama-mole.

Kungani amagremu ngemole ngayinye ehambisana nesisindo sefomula

Isisindo se-athomu esijwayelekile sesakhi siyisilinganiso esingenayunithi sezisindo ze-isotope zaso, esilinganiswe ngokuchichima kwazo kwemvelo futhi sivezwe maqondana nengxenye eyodwa kweyishumi nambili yesisindo se-athomu ye-carbon-12. I-mole yachazwa ekuqaleni ukuze i-mole eyodwa yento ibe nesisindo ngamagremu esilingana ngenombolo nesisindo se-athomu noma sefomula yayo. Kusukela ekuchazweni kabusha kwango-2019 lokho kufana akusafanele ngqo ngokwencazelo, kodwa kusasebenza cishe ngengxenye eyodwa kwezigidigidi. Isisindo se-athomu se-chlorine sicishe sibe ngu-35.45, ngakho isisindo sayo se-molar singu-35.45 g/mol, nakuba kungekho athomu eyodwa ye-chlorine enalesosisindo; i-chlorine yangempela yingxube ye-chlorine-35 ne-chlorine-37.

Lesi sihlahlandlela sisebenzisa izisindo ze-athomu ezijwayelekile ze-IUPAC eziyiswe ezindaweni ezimbili zamadesimali: H 1.01, C 12.01, N 14.01, O 16.00, Al 26.98, ne-S 32.06. Ukuthola isisindo se-molar senhlanganisela, hlanganisa izisindo ze-athomu zawo wonke ama-athomu kufomula, uphindaphinda ngalinye ngenombolo yalo engezansi nanoma yisiphi isiphindaphindi esingaphandle kwamabakaki.

Ku-aluminium sulfate, Al₂(SO₄)₃, amabakaki asho amaqembu amathathu e-sulfate. Iyunithi yefomula ngakho iqukethe i-Al engu-2, i-S engu-3, ne-O engu-12: 2(26.98) + 3(32.06) + 12(16.00) = 53.96 + 96.18 + 192.00 = 342.14 g/mol.

Imephu yamagremu, ama-mole nezinhlayiya

Yonke inkinga kulesi sihloko iyindlela edlula emabhokisini amathathu: isisindo ngamagremu, inani ngama-mole, nenani lezinhlayiya. Isisindo se-molar sixhuma lawo amabili okuqala; isilinganiso esingaguquki sika-Avogadro sixhuma amabili okugcina. Ama-mole ahlale eyisikhawu esiphakathi. Akukho ukuguqula ngqo kusuka kumagremu kuya ezinhlayiyeni okweqa i-mole.

Ngaphakathi kwebhokisi lezinhlayiya kunesinyathelo esisodwa esengeziwe. Ifomula ikutshela ukuthi ingakanani inani lama-athomu noma ama-ayoni ohlobo ngalunye emamolekyulini owodwa noma eyunithini yefomula eyodwa, futhi lezo zinombolo ezingezansi ziyizici eziqondile zokubala.

• Amagremu aye kuma-mole: hlukanisa ngesisindo se-molar (phindaphinda ngo-1 mol / M g).
• Ama-mole aye kumagremu: phindaphinda ngesisindo se-molar.
• Ama-mole aye ezinhlayiyeni: phindaphinda ngo-6.022 × 10²³ ngemole ngayinye.
• Izinhlayiya ziye kuma-mole: hlukanisa ngo-6.022 × 10²³ ngemole ngayinye.
• Amamolekyuli noma amayunithi efomula aye kuma-athomu noma kuma-ayoni: phindaphinda ngenombolo engezansi yaleyo athomu noma i-ayoni.

Isibonelo esisebenzile: kusuka kuma-milligram e-caffeine kuya kuma-athomu e-nitrogen

Isampula ye-caffeine, C₈H₁₀N₄O₂, inesisindo esingu-95.0 mg. Iqukethe amamolekyuli e-caffeine amangaki nama-athomu e-nitrogen amangaki?

Isinyathelo 1, isisindo se-molar: 8(12.01) + 10(1.01) + 4(14.01) + 2(16.00) = 96.08 + 10.10 + 56.04 + 32.00 = 194.22 g/mol. Isinyathelo 2, guqula isisindo sibe amagremu bese kuba ama-mole: 95.0 mg × (10⁻³ g / 1 mg) = 0.0950 g, no-0.0950 g × (1 mol / 194.22 g) = 4.8914 × 10⁻⁴ mol. Gcina izinombolo ezengeziwe okwamanje.

Isinyathelo 3, ama-mole aye kumamolekyuli: 4.8914 × 10⁻⁴ mol × 6.022 × 10²³ amamolekyuli/mol = 2.9456 × 10²⁰, kubikwe njengamamolekyuli angu-2.95 × 10²⁰. Isinyathelo 4, imolekyuli ngayinye inama-athomu e-nitrogen amane, ukubala okuqondile: 2.9456 × 10²⁰ × 4 = 1.18 × 10²¹ ama-athomu e-nitrogen. Isisindo esingu-95.0 mg sinezinombolo ezibalulekile ezintathu, ngakho nezimpendulo zombili zinazo.

Hlola usayizi: ingxenye yeshumi yegremu iyingxenye encane ye-mole yento enesisindo se-molar esicishe sibe ngu-200 g/mol, ngakho inani kufanele libe cishe u-0.1 ÷ 200 = 5 × 10⁻⁴ mol, futhi inani lamamolekyuli kufanele libe ngaphansi kakhulu kuka-10²³. Ukuhlola kokubili kuyaphumelela.

Isibonelo esisebenzile: kusuka enanini lamayunithi efomula kubuyela kumagremu

Isampula ye-aluminium sulfate iqukethe amayunithi efomula angu-3.15 × 10²². Isisindo sayo singakanani, futhi iqukethe ama-ayoni e-sulfate nama-athomu e-oxygen amangaki?

Isinyathelo 1, izinhlayiya ziye kuma-mole: 3.15 × 10²² ÷ 6.022 × 10²³ mol⁻¹ = 0.052308 mol. Isinyathelo 2, ama-mole aye kumagremu usebenzisa isisindo se-molar esitholwe ngaphambilini: 0.052308 mol × 342.14 g/mol = 17.897 g, kubikwe njengo-17.9 g.

Isinyathelo 3, sebenzisa ifomula njengethuluzi lokubala. Iyunithi yefomula ngayinye ye-Al₂(SO₄)₃ iqukethe ama-ayoni amathathu e-sulfate, SO₄²⁻, ngakho isampula iphethe ama-ayoni e-sulfate angu-3 × 3.15 × 10²² = 9.45 × 10²². Iyunithi yefomula ngayinye inama-athomu e-oxygen angu-12, ngakho isampula iphethe ama-athomu e-oxygen angu-12 × 3.15 × 10²² = 3.78 × 10²³, okungaphezu kancane kwengxenye ye-mole yama-athomu e-oxygen. Izinhlanganisela ze-ayoni zakhiwe ngamayunithi efomula hhayi amamolekyuli, kodwa umqondo wokubala uyafana.

Amaphutha ama-mole ayiyo avela ekulahlekelweni ukuthi yiyiphi inhlangano

Amaphutha amaningi ama-mole akayona amaphutha ezibalo. Avela ekukhohlweni ukuthi yini ebalwayo noma ekusebenziseni isici ngendlela engafanele. Isilinganiso esisheshayo ngaphambi kokubala siwabamba amaningi awo.

Bhala wonke inani nayo iyunithi yalo nenhlangano yalo, njengo-0.0523 mol Al₂(SO₄)₃ noma ama-ayoni e-SO₄²⁻ angu-9.45 × 10²², futhi uqambe umcibisholo emepheni yamagremu, ama-mole nezinhlayiya olandelwa yisinyathelo ngasinye. Isinyathelo esingahambisani nanoma yimuphi umcibisholo ngokuvamile siyiphutha.

• Ukuxuba ama-athomu namamolekyuli: i-1.0 mol ye-O₂ inesisindo esingu-32.00 g, hhayi u-16.00 g, futhi iqukethe i-2.0 mol yama-athomu e-O.
• Ukunganaki isiphindaphindi esingaphandle kwamabakaki: ku-Al₂(SO₄)₃ kunama-athomu e-oxygen angu-12 ngeyunithi yefomula ngayinye, hhayi angu-4.
• Ukuphindaphinda ngesilinganiso esingaguquki sika-Avogadro lapho kuguqulwa izinhlayiya zibe ama-mole: inani ngama-mole lesampula yelabhorethri evamile kufanele libe yinombolo ephakathi nendawo, hhayi into eseduze no-10²³ noma ngaphezulu.
• Ukusebenzisa inombolo yesisindo esikhundleni sesisindo se-athomu: i-chlorine ingu-35.45 g/mol, hhayi u-35 noma u-37.
• Ukweqa i-mole: amagremu awakwazi ukuguqulwa ngqo abe yizinhlayiya noma abe amagremu entweni ehlukile.
• Ukuyisa isisindo se-molar noma amanani aphakathi msinyane kakhulu, okungashintsha inombolo yokugcina ebikiwe.