Amafomula e-empirical nawamolekyuli avela kudatha

Isilinganiso esilula kakhulu uma kuqhathaniswa nokwakheka kwangempela

Ifomula ye-empirical inikeza isilinganiso esincane kakhulu senombolo ephelele yama-athomu enhlanganisela. Ifomula yamolekyuli inikeza inani langempela lama-athomu ohlobo ngalunye emamolekyulini owodwa, futhi ihlale iyisiphindaphindi senombolo ephelele sefomula ye-empirical. I-hydrogen peroxide inefomula yamolekyuli engu-H₂O₂ nefomula ye-empirical engu-HO. I-glucose, C₆H₁₂O₆, inefomula ye-empirical engu-CH₂O, ayabelana nayo ne-formaldehyde ne-acetic acid.

Idatha yesisindo kuphela ingaveza ifomula ye-empirical kuphela, ngoba i-H₂O₂ ne-HO zinezinkomba zamaphesenti ezifanayo. Kudingeka isilinganiso esihlukile sesisindo se-molar ukuthola isiphindaphindi. Ezinhlanganiselweni ze-ayoni ezifana ne-sodium chloride, eziba yizakhiwo ze-lattice ezinweba ngaphandle kwamamolekyuli ahlukene, iyunithi yefomula ivame ukubhalwa njengefomula ye-empirical ngokwesivumelwano. Okuhlukile kugcina i-ayoni enama-athomu amaningi injalo, njengase-sodium peroxide, Na₂O₂, equkethe i-ayoni ye-peroxide O₂²⁻.

Ukwakheka kwamaphesenti evela kufomula eyaziwayo

Iphesenti lesisindo sesakhi lingesisindo salesosakhi ku-mole eyodwa yenhlanganisela esihlukaniswe ngesisindo se-molar, siphindaphindwe ngo-100. 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, S 32.06, ne-Fe 55.85.

Isibonelo esisebenzile 1. I-ammonium sulfate, (NH₄)₂SO₄, isetshenziswa njengomanyolo we-nitrogen. Iphesenti layo lesisindo se-nitrogen lingakanani? Iyunithi eyodwa yefomula iqukethe i-N engu-2, i-H engu-8, i-S engu-1 ne-O engu-4, ngakho isisindo se-molar singu-2(14.01) + 8(1.01) + 32.06 + 4(16.00) = 28.02 + 8.08 + 32.06 + 64.00 = 132.16 g/mol. I-nitrogen: 28.02 ÷ 132.16 × 100 = 21.20% N. Ezinye izakhi zingu-6.11% H, 24.26% S, ne-48.43% O, futhi amanani amane ahlangana abe ngu-100.00%, ukuhlola okusizayo ukuthi akukho athomu eliweleyo.

Ukuguqula izisindo zibe yisilinganiso sama-mole senombolo ephelele

Izinombolo ezingezansi zibala ama-athomu, futhi ama-athomu abalwa ngama-mole, ngakho indlela ihlale idlula kuma-mole. Amagremu ezakhi ezahlukene awakwazi ukuqhathaniswa ngqo ngoba ama-athomu azo anezisindo ezahlukene.

Isinyathelo sokususa idesimali sibe yingxenye sidinga ukwahlulela. Izilinganiso zokuhlola zingavamile ukuba ngqo, ngakho inani elingaphakathi cishe kuka-0.1 lenombolo ephelele ngokuvamile lingayiswa, kodwa inani eliseduze no-1.5, 1.33, 1.67, 1.25 noma 1.75 likhomba ingxenye. Phindaphinda zonke izilinganiso ngo-2, 3 noma 4 njengoba kufanele. Isibonelo, isampula ye-iron oxide equkethe u-1.737 g Fe no-0.747 g O inikeza i-0.03110 mol Fe ne-0.0467 mol O. Isilinganiso se-O:Fe singu-1.50, ngakho ukuphindaphinda kabili kunikeza i-Fe₂O₃.

• Qala ngezisindo. Uma unamaphesenti, cabanga isampula engu-100 g ukuze iphesenti ngalinye libe amagremu.
• Guqula isisindo ngasinye sibe ama-mole usebenzisa isisindo se-athomu salesosakhi.
• Hlukanisa wonke amanani ama-mole ngelincane kunawo wonke.
• Uma noma yisiphi isilinganiso singasondelene nenombolo ephelele, phindaphinda zonke izilinganiso ngenombolo ephelele encane kakhulu ezenza zibe ngephelele.
• Bhala izinombolo ezingezansi ngokulandelana okujwayelekile (ezinhlanganiselweni ze-organic, u-C kuqala, bese u-H, bese okunye ngokulandelana kwe-alfabhethi).

Isibonelo esisebenzile: i-carboxylic acid kusuka ekwakhekeni kwamaphesenti

Isibonelo esisebenzile 2. Ukuhlaziya i-asidi emhlophe enekristalu kunikeza u-40.68% C, 5.13% H, no-54.19% O ngesisindo. Isilinganiso esihlukile sibeka isisindo sayo se-molar ku-118 g/mol. Thola amafomula e-empirical nawamolekyuli.

Cabanga u-100 g, ngakho isampula iqukethe u-40.68 g we-C, u-5.13 g we-H no-54.19 g we-O. Guqula ube ama-mole: 40.68 g ÷ 12.01 g/mol = 3.387 mol C; 5.13 g ÷ 1.01 g/mol = 5.079 mol H; 54.19 g ÷ 16.00 g/mol = 3.387 mol O. Hlukanisa ngenani elincane, 3.387: C 1.000, H 1.500, O 1.000.

Isilinganiso se-hydrogen esingu-1.500 siyingxenye, hhayi iphutha lokuyisa, ngakho phindaphinda zonke izilinganiso ngo-2: C₂H₃O₂. Isisindo sayo sefomula singu-2(12.01) + 3(1.01) + 2(16.00) = 59.05 g/mol. Isiphindaphindi singu-118 ÷ 59.05 = 2.00, ngakho ifomula yamolekyuli ingu-C₄H₆O₄. Leli yifomula ye-succinic acid. Ukuyisa u-1.5 ku-2 bekuzonikeza i-CH₂O (30.03 g/mol), futhi u-118 ÷ 30.03 = 3.93 akayona inombolo ephelele, uphawu lokuthi ifomula ye-empirical ayilungile.

Isibonelo esisebenzile: ukuhlaziya ukusha koketshezi lwe-organic

Isibonelo esisebenzile 3. Isampula engu-0.3150 g yoketshezi oluqukethe i-C, i-H ne-O kuphela ishiswa ngokuphelele ku-oxygen eyeqile. Ikhiqiza u-0.6293 g CO₂ no-0.2577 g H₂O. Umhwamuko unesisindo se-molar esicishe sibe ngu-88 g/mol. Thola amafomula womabili.

Wonke ama-carbon aphela ku-CO₂ futhi wonke ama-hydrogen aphela ku-H₂O. Isisindo se-C = 0.6293 g CO₂ × (12.01 g C / 44.01 g CO₂) = 0.17173 g. Isisindo se-H = 0.2577 g H₂O × (2.02 g H / 18.02 g H₂O) = 0.028888 g. I-oxygen ayikwazi ukulandelelwa ngendlela efanayo, ngoba ingxenye enkulu ye-oxygen emikhiqizweni yavela ekuhlinzekweni kwe-O₂, ngakho yithole ngomehluko: 0.3150 − 0.17173 − 0.028888 = 0.11438 g O.

Ama-mole: 0.17173 ÷ 12.01 = 0.014299 mol C; 0.028888 ÷ 1.01 = 0.028602 mol H; 0.11438 ÷ 16.00 = 0.0071488 mol O. Ukuhlukanisa ngo-0.0071488 kunikeza 2.000 : 4.001 : 1, ngakho ifomula ye-empirical ingu-C₂H₄O, enesisindo sefomula esingu-44.06 g/mol. Isiphindaphindi singu-88 ÷ 44.06 = 2.0, okunikeza u-C₄H₈O₂. Izinhlanganisela eziningana ezahlukene zabelana ngale fomula yamolekyuli, kuhlanganise ne-ethyl acetate ne-butanoic acid, ngakho ukukhomba into kudinga ubufakazi besakhiwo njenge-spectroscopy.

Lapho izibalo zefomula ye-empirical ziphuthisa khona

Amaphutha amaningi senzeka ezindaweni ezimbili: ekukhetheni ukuthi yini eguqulwa ibe ama-mole, nasekunqumeni ukuthi isilinganiso esingeyona inombolo ephelele siphathwa kanjani. Hlola zombili ngaphambi kokubhala ifomula yokugcina.

Bese uhlola impendulo ngedatha. Bala kabusha ukwakheka kwamaphesenti yefomula oyiphakamisayo bese uyiqhathanisa namanani alinganisiwe; idatha enhle ivame ukuvumelana phakathi kweshumi eliningana lephesenti. Esibonelweni esisebenzile 2, i-C₄H₆O₄ inikeza u-40.68% C, 5.13% H, no-54.19% O, okuhambisana nokuhlaziywa.

• Ukuyisa isilinganiso esingu-1.5 noma 1.33 enanini eliphelele eliseduze esikhundleni sokuphindaphinda konke.
• Ukuyisa amanani ama-mole kunombolo eyodwa noma ezimbili ezibalulekile, okungaphendula u-1.50 oqondile ube into engaqondakali.
• Ukuhlukanisa isisindo se-oxygen ngo-32.00 g/mol. Sebenzisa isisindo se-athomu se-O, 16.00, ngoba izinombolo ezingezansi zibala ama-athomu.
• Ukunikeza i-oxygen emikhiqizweni yokusha isampula. Thola i-oxygen yesampula ngomehluko.
• Ukunganaki isakhi esingekho. Uma amaphesenti anikeziwe ehlangana abe ngaphansi kakhulu kuka-100%, kukhona esinye isakhi, kaningi i-oxygen.
• Ukwamukela isiphindaphindi samolekyuli esingeyona inombolo ephelele. Uma isisindo se-molar ÷ isisindo sefomula ye-empirical singasondelene nenombolo ephelele, hlola kabusha ifomula ye-empirical.