I-Molarity, ukuhlanjulula ne-stoichiometry yesixazululo

I-molarity ibala ama-mole ngeliter ngalinye lesixazululo

I-molarity, ebizwa nangokuthi ukugxila kwenani, inani le-solute ngama-mole elihlukaniswe ngevolumu yesixazululo ngama-liter: c = n/V, ngo-mol/L, kaningi kubhalwe M. Isixazululo se-glucose esingu-0.250 mol/L siqukethe u-0.250 mol we-glucose ku-liter ngalinye lesixazululo sokugcina. Amabakaki anyathelayo akhomba ukugxila kwe-molar kohlobo, njengo-[Cl⁻].

Ivolumu iyivolumu yesixazululo, hhayi yesincibilikisi. Ukuncibilikisa i-solute ku-1.000 L ngqo yamanzi ngokuvamile kunikeza ivolumu ephelele engeyona u-1.000 L, ngakho izixazululo zenziwa zize kumaka wokulinganisa efilasikini yevolumu kunokungeza ivolumu elinganisiwe yamanzi.

Ku-electrolyte eqinile, ukugxila kwama-ayoni kulandela ifomula. Isixazululo se-CaCl₂ esingu-0.150 mol/L singu-0.150 mol/L ku-Ca²⁺ no-0.300 mol/L ku-Cl⁻, ngoba iyunithi yefomula ngayinye ikhulula ama-ayoni amabili e-chloride. I-molarity nayo ishintsha kancane ngezinga lokushisa, ngoba izixazululo ziyanwebeka lapho zishiswa.

Ukulungisa isixazululo kusuka entweni eqinile ekalwe

Inani elidingekayo ngu-n = c × V, futhi isisindo sokukala ngu-n × M, lapho u-M kuyisisindo se-molar. Kala into eqinile, uyincibilikise emanzini angaphansi kwevolumu yokugcina, uyidlulisele efilasikini yevolumu ngenkathi uhlanza ibhikha uthulule efilasikini, hlanjulula ufike kumaka, uxube ngokuyiphendula.

Isibonelo esisebenzile: lungisa u-250.0 mL we-copper(II) sulfate engu-0.0800 mol/L kusuka kumakristalu aluhlaza okwesibhakabhaka e-copper(II) sulfate pentahydrate, CuSO₄·5H₂O. Ngezisindo ze-athomu ezijwayelekile ze-IUPAC eziyiswe emadesimalini amabili (Cu 63.55, S 32.06, O 16.00, H 1.01), isisindo se-molar se-hydrate singu-63.55 + 32.06 + 4(16.00) + 5(18.02) = 249.71 g/mol.

n = 0.0800 mol/L × 0.2500 L = 0.02000 mol. Isisindo = 0.02000 mol × 249.71 g/mol = 4.994 g, ngakho kala u-4.99 g we-pentahydrate. Iyunithi yefomula ngayinye isanikeza i-Cu²⁺ eyodwa ne-SO₄²⁻ eyodwa, kodwa amanzi e-hydration engeza esisindweni osikalayo. Ukube usebenzise isisindo se-molar se-anhydrous, 159.61 g/mol, wakala u-3.19 g we-hydrate, isixazululo besizoba ngu-0.0511 mol/L kuphela, cishe ngu-36% ngaphansi kokugxila okufanele.

Ukuhlanjulula isixazululo esiyisisekelo nge-C₁V₁ = C₂V₂

Ukwengeza isincibilikisi kushintsha ivolumu kodwa hhayi inani le-solute. Njengoba n = cV ngaphambi nangemva kokuhlanjulula, C₁V₁ = C₂V₂, lapho u-1 ukhomba isixazululo esiyisisekelo no-2 esihlanjululiwe. Noma iyiphi iyunithi yevolumu iyasebenza uma amavolumu womabili asebenzisa efanayo, ngoba amayunithi ayakhansela.

Isibonelo esisebenzile: udinga u-500.0 mL we-sodium chloride engu-0.360 mol/L futhi unesixazululo esiyisisekelo esingu-2.40 mol/L. V₁ = C₂V₂ ÷ C₁ = (0.360 mol/L × 500.0 mL) ÷ 2.40 mol/L = 75.0 mL. Hlola: isixazululo esiyisisekelo sigxile ngo-2.40 ÷ 0.360 = izikhathi ezingu-6.67, ngakho udinga cishe ingxenye eyodwa kweziyisikhombisa yevolumu yokugcina, no-500.0 mL ÷ 6.67 = 75.0 mL.

Linganisa u-75.0 mL wesixazululo esiyisisekelo efilasikini yevolumu engu-500-mL bese uhlanjulula uze ufike kumaka. Ungavele wengeze u-425.0 mL wamanzi: amavolumu ezixazululo awahlangani ngokuqinile, futhi u-C₂ ukhomba ivolumu yokugcina. Uma uhlanjulula i-asidi egxilile, engeza i-asidi emanzini hhayi amanzi ku-asidi, ngoba ukushisa okukhululwayo kungabangela ukuchichima.

I-stoichiometry yesixazululo: kusuka kuvolumu kuya kuma-mole nokubuyela emuva

Ekusabeleni phakathi kwezixazululo, i-molarity iguqula ivolumu ibe ama-mole nge-n = c × V. Isilinganiso sama-mole esivela esibalweni esilinganisiwe bese sisebenza njengoba senza ku-stoichiometry esekelwe esisindweni, futhi i-molarity yesibili iguqulela emuva kuvolumu uma kudingeka.

Isibonelo esisebenzile: yimuphi umthamo we-barium chloride engu-0.125 mol/L onethisa yonke i-sulfate ku-40.0 mL we-sodium sulfate engu-0.0850 mol/L, futhi yisiphi isisindo se-barium sulfate esakhekayo? Isibalo se-ayoni esicwengiwe ngu-Ba²⁺(aq) + SO₄²⁻(aq) → BaSO₄(s). n(SO₄²⁻) = 0.0850 mol/L × 0.0400 L = 3.40 × 10⁻³ mol. Isilinganiso singu-1:1, futhi i-BaCl₂ ngayinye inikeza i-Ba²⁺ eyodwa, ngakho V = 3.40 × 10⁻³ mol ÷ 0.125 mol/L = 0.0272 L, noma 27.2 mL.

Isisindo se-molar se-BaSO₄ (Ba 137.33, S 32.06, O 16.00) singu-233.39 g/mol, ngakho isisindo esakhekayo singu-3.40 × 10⁻³ mol × 233.39 g/mol = 0.794 g. Impendulo ngayinye inezinombolo ezibalulekile ezintathu, ezibekwe ngu-0.0850 mol/L, 40.0 mL no-0.125 mol/L.

I-titration: ukuguqula ukufundwa kwe-buret kube ukugxila

Ku-titration, isixazululo esinokugxila okwaziwayo, i-titrant, sengezwa ku-buret kuvolumu elinganisiwe yesampula kuze kuphele ukusabela. Iphuzu lokulingana yilapho inani le-titrant elengeziwe lifana nesampula ngesilinganiso se-stoichiometry. Iphuzu lokugcina yilapho isikhombisi sishintsha umbala, futhi isikhombisi esifanele senza lezi zimbili zicishe zifane.

Isibonelo esisebenzile: isampula engu-20.00 mL yesixazululo se-barium hydroxide esinokugxila okungaziwa idinga u-28.36 mL we-hydrochloric acid engu-0.1208 mol/L ukuze ifinyelele iphuzu lokugcina le-phenolphthalein. Ba(OH)₂(aq) + 2 HCl(aq) → BaCl₂(aq) + 2 H₂O(l). n(HCl) = 0.1208 mol/L × 0.02836 L = 3.426 × 10⁻³ mol. n(Ba(OH)₂) = 3.426 × 10⁻³ mol ÷ 2 = 1.713 × 10⁻³ mol. c(Ba(OH)₂) = 1.713 × 10⁻³ mol ÷ 0.02000 L = 0.08565 mol/L, ngezinombolo ezibalulekile ezine.

Isici sika-2 sibalulekile. Ukuthatha ukusabela njengo-1:1 bekuzonikeza u-0.1713 mol/L, kabili inani langempela, yingakho i-C₁V₁ = C₂V₂ ingafanele isetshenziswe ku-titration. Ukugxila kwe-titrant ngokwayo kumiswa kuqala nge-standardization, ukuyi-titrayisha ngokumelene nokuvamile okukalwe okuyisisekelo; i-sodium carbonate ikhetho elivamile lama-asidi.

Amaphutha okugxila nendlela yokuwabona

Amaphutha amaningi okugxila angamaphutha amayunithi noma okusetha. Ukubhala amayunithi kunani ngalinye, nokuhlola ukuthi umphumela uya ngendlela elindelekile, kubamba cishe wonke.

Isixazululo esihlanjululiwe kumele singagxili kangako kunesisekelo saso, isisindo esikalelwe i-hydrate kumele sibe sikhulu kunaleso se-anhydrous, futhi ivolumu ye-titrant kufanele iwele ebangeni le-buret. Umphumela ophula noma yimuphi walokhu ufanele ubukwe futhi.

• Ukusebenzisa ama-milliliter ku-n = c × V no-c ngo-mol/L. Guqula ube ama-liter kuqala; mL × mol/L akunikezi mol.
• Ukusebenzisa ivolumu yesincibilikisi esikhundleni sevolumu yokugcina yesixazululo.
• Ukusebenzisa isisindo se-molar se-anhydrous ku-hydrate.
• Ukusebenzisa i-C₁V₁ = C₂V₂ ekusabeleni. Ichaza ukuhlanjulula kuphela; ekusabeleni, dlula ngama-mole nesilinganiso sama-mole.
• Ukukhohlwa inani lama-ayoni, njengokuthatha i-CaCl₂ engu-0.150 mol/L njengo-0.150 mol/L ku-Cl⁻.
• Ukwengeza ivolumu yokugcina yamanzi esikhundleni sokuhlanjulula kuze kufike kuvolumu yokugcina.