Hluav taws xob dissociation: theoretical foundations ntawm electrochemistry

2024 Tus sau: Howard Calhoun | [email protected]. Kawg hloov kho: 2023-12-17 10:28

Kev sib cais hluav taws xob ua lub luag haujlwm loj hauv peb lub neej, txawm tias peb feem ntau tsis xav txog nws. Nws yog nrog qhov tshwm sim no uas cov hluav taws xob conductivity ntawm ntsev, acids thiab cov hauv paus hauv cov kua nruab nrab yog txuam nrog. Los ntawm thawj lub plawv dhia los ntawm "nyob" hluav taws xob nyob rau hauv tib neeg lub cev, uas yog yim caum feem pua kua kua, rau lub tsheb, xov tooj ntawm tes thiab cov players, cov roj teeb uas tseem ceeb yog cov roj teeb hluav taws xob, hluav taws xob dissociation yog invisibly muaj nyob txhua qhov chaw nyob ze peb.

Nyob rau hauv cov vats loj heev uas tawm cov pa phem los ntawm bauxite melted ntawm qhov kub thiab txias, "tis" hlau - txhuas yog tau los ntawm electrolysis. Txhua yam nyob ib puag ncig peb, los ntawm chrome radiator grilles rau nyiaj-plated tsej hauv peb pob ntseg, ib zauglos yog ntsib nrog kev daws teeb meem los yog molten ntsev, thiab li no nrog qhov tshwm sim. Nws tsis yog rau tsis muaj dab tsi uas hluav taws xob dissociation yog kawm los ntawm tag nrho cov ceg ntawm science - electrochemistry.

Thaum yaj, cov molecules ntawm cov kua ua kua ua kua nkag mus rau hauv cov tshuaj lom neeg nrog cov molecules ntawm cov tshuaj yaj, tsim cov solvates. Nyob rau hauv ib tug aqueous tov, ntsev, acids thiab bases yog feem ntau raug rau dissociation. Raws li cov txheej txheem no, cov kua dej molecules tuaj yeem decompose rau hauv ions. Piv txwv li, nyob rau hauv kev cuam tshuam ntawm cov kuab tshuaj aqueous, Na⁺ thiab CI^{- ions hauv NaCl ionic siv lead ua dhau mus rau qhov hnyav nruab nrab hauv ib qho. tshiab zoo ntawm solvated (hydrated) particles.}

Qhov tshwm sim no, uas yog qhov tseem ceeb ntawm cov txheej txheem ua tiav lossis ib nrab decomposition ntawm cov tshuaj yaj mus rau hauv ions raws li qhov tshwm sim ntawm qhov hnyav, hu ua "hluav taws xob dissociation". Cov txheej txheem no tseem ceeb heev rau electrochemistry. Qhov tseem ceeb tshaj plaws yog qhov tseeb tias dissociation ntawm complex multicomponent systems yog characterized by stepwise flow. Nrog rau qhov tshwm sim no, kuj tseem muaj qhov nce ntxiv ntawm cov ions hauv cov tshuaj, uas txawv cov tshuaj electrolytic los ntawm cov uas tsis yog electrolytic.

Nyob rau hauv cov txheej txheem ntawm electrolysis, ions muaj cov kev taw qhia meej ntawm kev txav: cov khoom uas muaj tus nqi zoo (cations) - mus rau qhov tsis zoo electrode, hu ua cathode, thiab zoo ions (anions) - rau lub anode, electrode nrog tus nqi rov qab, qhov twg lawv tawm. Cations raug txo thiab anions yog oxidized. Yog li ntawd, dissociation yog ib tug reversible txheej txheem.

Ib qho ntawm cov yam ntxwv tseem ceeb ntawm cov txheej txheem electrochemical no yog qib ntawm electrolytic dissociation, uas yog qhia raws li qhov piv ntawm cov hydrated hais rau tag nrho cov molecules ntawm cov khoom yaj. Qhov ntsuas no siab dua, qhov muaj zog ntawm electrolyte yog cov khoom no. Raws li lub hauv paus no, txhua yam khoom raug muab faib ua qaug zog, nruab nrab lub zog thiab muaj zog electrolytes.

Lub degree ntawm dissociation nyob ntawm cov nram qab no yam: a) qhov ntawm lub solute; b) qhov xwm ntawm cov kuab tshuaj, nws cov dielectric tas li thiab polarity; c) concentration ntawm kev daws (qhov ntsuas no qis dua, qhov ntau dua qhov kev sib cais); d) qhov kub ntawm qhov nruab nrab dissolving. Piv txwv li, kev sib cais ntawm acetic acid tuaj yeem qhia los ntawm cov qauv hauv qab no:

CH₃COOH⁺ +₃COO^-

Muaj zog electrolytes dissociate yuav luag irreversibly, txij li thaum lawv cov aqueous tov tsis muaj cov thawj molecules thiab tsis-hydrated ions. Nws tseem yuav tsum tau ntxiv tias txhua yam khoom uas muaj ionic thiab covalent polar hom tshuaj tiv thaiv yog raug rau cov txheej txheem dissociation. Txoj kev xav ntawm electrolytic dissociation yog tsim los ntawm Swedish physicist thiab chemist Svante Arrhenius nyob rau hauv 1887.