Pab ua hauj lwm los ntawm lub tshav kub ntawm cov ib puag ncig

Part 1. Ib txhia nqe lus thiab txhais cov ntsiab.

Lub electromotive quab yuam (emf) yog ib sab nraud quab yuam teb feem muaj ib tug tam sim no qhov twg los ... lwm quab yuam sawv nyob rau hauv electroplating hlwb nyob rau hauv ib thaj tsam ntawm lub ntsha thiab cov electrodes. Lawv kuj khiav lag luam rau tus ciam ntawm ob txawv co thiab txiav txim seb cov kev sib cuag tej zaum txawv therebetween [5, p. 193, 191]. Nyiaj jumps potentials rau tag nrho cov txee ntawm lub Circuit Court seem yog sib npaug zos rau lub peev xwm sib txawv nruab nrab ntawm tus conductors, nyob rau ntawm lub saw xaus, thiab yog hu ua tus electromotive quab yuam emf neeg xyuas pib Circuit Court ... saw muaj xwb ntawm conductors ntawm cov thawj zoo yog sib npaug zos rau lub peev xwm dhia ntawm tus thawj thiab tus kawg neeg xyuas pib nyob rau hauv ncaj qha hu rau lawv (Volta txoj cai) ... Yog hais tias cov Circuit Court yog kom qhib, lub emf no Circuit Court yog pes tsawg. Yuav kom kho cov qhib-Circuit Court neeg xyuas pib, uas muaj xws li ntawm tsawg kawg yog ib tug ntsha, kev cai volts ... Obviously, tsuas neeg xyuas pib Circuit Court muaj tsawg kawg yog ib neeg xyuas pib ntawm lub thib ob hom yog electrochemical hlwb (los yog chains electrochemical ntsiab) [1, p. 490 - 491].

Polyelectrolytes yog polymers muaj peev xwm ntawm dissociating rau hauv ions nyob rau hauv cov tshuaj, yog li nyob rau hauv tib macromolecule, ib tug loj tus naj npawb ntawm rov muaj dua nqi ... crosslinked polyelectrolytes (ion exchangers, ion-pauv cob) tsis yaj, tsuas swell, thaum cov lus muaj peev xwm dissociate [6, p. 320 - 321]. Polyelectrolytes dissociate rau hauv tsis zoo them macroion thiab H + ions yog hu ua polyacids thiab dissociates rau hauv zoo them ions thiab OH- macroion hu ua poliosnovaniyami.

Donnan equilibrium peev xwm yog lub peev xwm sib txawv uas tshwm sim nyob rau theem ciam nruab nrab ntawm ob electrolytes yog hais tias qhov txwv yog tsis permeable rau tag nrho cov ions. Impermeability txwv rau ib co ions tej zaum yuav tshwm sim los, piv txwv li, lub xub ntiag ntawm week nrog nqaim heev pores uas tsis tau lawm rau hais saum toj no ib tug me me. Selective permeability ntawm lub interface tshwm sim thiab yog hais tias tej ions thiaj li txuas rau ib yam ntawm cov theem uas tawm nws feem ntau tsis tau. Raws nraim coj ionic ion pauv resins, los yog ion-pauv pab pawg neeg tsau homopolar daim ntawv cog lus nyob rau hauv lub molecular lattice los yog matrix. Cov tshuaj, ua hauv xws matrices ntaub ntawv ua ke nrog nws ib tug tib theem; tov, nyob sab nraum, - tus thib ob [7. 77].

Cov hluav taws xob muab ob npaug rau txheej (EDL) yog tshwm sim nyob rau hauv cov interface ntawm ob theem teev ntawm oppositely them khaubncaws sab nraud povtseg pov tseg ntawm ib tug tej yam deb ntawm txhua lwm yam [7. 96].

Peltier effect no rho tawm los yog haum ntawm tshav kub ntawm kev sib cuag ntawm ob tug sib txawv conductors raws li cov kev taw qhia ntawm hluav taws xob tam sim no ntws los ntawm cov kev sib cuag [2, p. 552].

Part 2: Siv lub tshav kub nruab nrab nyob rau hauv lub electrolysis ntawm cov dej.

Xav txog cov mechanism ntawm tshwm sim ntawm lub Circuit Court ntawm lub electrochemical cell (hereinafter caij), qhia schematically nyob rau hauv Daim duab. 1, ntau emf vim lub internal hu tej zaum txawv (PKK) thiab cov nyhuv ntawm Donnan (nyuag lus piav qhia txog lub essence ntawm cov Donnan nyhuv, nrog PKK thiab txuam Peltier tshav kub yog muab nyob rau hauv peb ib feem ntawm qhov tsab xov xwm).

Daim duab. 1. Schematic sawv cev ntawm ib tug electrochemical cell: 1 - lub cathode yog hu nrog ib tug daws ntawm 3, lub electrochemical yuav txo tau cov tshuaj tiv thaiv ntawm lub ntsha cations tshwm sim rau nws saum npoo, ua los ntawm ib tug sib inert hnyav ncawv doped n-semiconductor. Ib feem ntawm cov cathode txuas mus rau ib tug sab nraud voltage qhov twg los, metallized; 2 - tus anode yog hu nrog ib tug daws ntawm 4, rau ntawm qhov chaw ntawd tshwm sim electrochemical oxidation cov tshuaj tiv thaiv ntawm lub ntsha anions, ua los ntawm sib inert hnyav ncawv doped p-semiconductor. Ib feem ntawm cov anode txuas mus rau ib tug sab nraud voltage qhov twg los, metallized; 3 - cathode qhov chaw, polyelectrolyte tshuaj, dissociating nyob rau hauv dej ntawm macroion R- zoo them thiab zoo them counterions me me K + (nyob rau hauv lub tam sim no piv txwv yog lub hydrogen ion H +); 4 - anode compartment polyelectrolyte daws nyob rau hauv dej dissociating rau hauv zoo them macroion R + thiab tsis zoo them counterions me me A- (nyob rau hauv qhov kev piv txwv nws hydroxide ions OH-); 5 - daim nyias nyias (diaphragm), yog impermeable mus macromolecules (macroion) polyelectrolytes, tab sis tag permeable rau me me counterions K +, A- thiab dej lwg me me qhia qhov chaw 3 thiab 4; Evnesh - ib tug sab nraud voltage qhov chaw.

Emf los ntawm Donnan nyhuv

Rau clarity, lub ntsha ntawm lub cathode qhov chaw (. 3, Daim duab 1) yog xaiv aqueous polyacid tshuaj (R-H +), cov ntsha thiab cov anode compartment (4, Daim duab 1.) - aqueous poliosnovaniya (R + OH-). Raws li ib tug tshwm sim ntawm dissociation polyacids nyob rau hauv lub cathode compartment, nyob ze ntawm qhov chaw ntawm lub cathode (1, Daim duab. 1), muaj ib tug muaj zog concentration ntawm H + ions. Zoo them nyiaj tshwm nyob rau hauv lub cheeb tsam ntawm lub cathode nto tsis compensated zoo them macroions R-, txij li thaum lawv yuav tsis tuaj ze rau ntawm qhov chaw ntawm lub cathode vim nws loj thiab muaj ib tug zoo them ionic cua (kom paub meej saib. hauj lwm Donnan cov nyhuv hauv Annex №1 ntawm peb ib feem ntawm qhov tsab xov xwm). Yog li, tus ciam txheej ntawm ib tug tov ncaj qha nyob rau hauv kev sib cuag nrog lub cathode nto muaj ib tug zoo xwb. Raws li ib tug tshwm sim, ib tug electrostatic induction rau lub cathode nto, contiguous nrog cov tshuaj, muaj yog ib tug tsis zoo coj lub conduction electrons. Xws li ntawm lub interface ntawm lub cathode nto thiab tej kev lav ris tov tshwm sim. Teb ntawm lub tej kev lav ris pushes electrons los ntawm cov cathode - rau cov tshuaj.

Ib yam li ntawd, nyob rau hauv anode (2, Daim duab. 1), tus ciam txheej ntawm cov tshuaj nyob rau hauv lub anode compartment (4, Daim duab. 1) ncaj qha nyob rau hauv kev sib cuag nrog lub anode nto muaj ib tug tsis zoo xwb, thiab nyob rau hauv anode nto, contiguous nrog cov tshuaj, muaj yog ib tug zoo xwb. Xws li ntawm lub interface ntawm lub anode nto thiab kev daws kuj tshwm sim tej kev lav ris. Teb ntawm lub tej kev lav ris pushes electrons los ntawm cov tshuaj - ib tug anode.

Yog li, lub tshav pob ntawm tej kev lav ris ntawm lub interfaces ntawm lub cathode thiab anode nrog cov tshuaj, kev txhawb thermal tshuaj ion diffusion, yog ob tug emf qhov twg los, kuj nyob rau hauv kev hais kwv txhiaj nrog ib tug sab nraud qhov chaw, i.e., thawb tau tus tsis zoo nqi nyob rau hauv lub voj counterclockwise.

Dissociation poliosnovaniya polyacids thiab kuj ua rau thermal diffusion los ntawm daim nyias nyias (5, Daim duab 1). H + ions ntawm cov cathodic qhov chaw - mus rau lub anode, thiab OH- ions ntawm cov anode compartment - ib tug cathode. Macroion R + thiab R- polyelectrolytes tsis tau tsiv mus los ntawm daim nyias nyias, ces nws los ntawm cov cathode qhov chaw muaj ib tug dhau heev lawm tsis zoo xwb, thiab los ntawm cov anodic qhov chaw - ib tug dhau heev lawm zoo xwb, i.e., muaj lwm DPP vim lub Donnan nyhuv. Yog li, daim nyias nyias kuj tshwm sim hauv lub emf, kuj nyob rau hauv kev hais kwv txhiaj nrog ib tug sab nraud qhov chaw ntawm tshav kub diffusion thiab khaws cia cov tshuaj ntawm ions.

Nyob rau hauv peb tus yam ntxwv, tus voltage thoob plaws lub membrane yuav ncav cuag 0,83 volts, raws li no raws li ib tug kev hloov nyob rau hauv tej zaum ntawm standard hydrogen electrode los ntawm - 0,83 0 volts nyob rau txoj kev hloov mus los ntawm lub alkaline nruab nrab nyob rau hauv lub anode compartment lub cathode compartment acidic ib puag ncig. Kom paub meej, saib. Nyob rau hauv Annex №1 ntawm peb ib feem ntawm qhov tsab xov xwm.

Emf PKK los ntawm lub sab hauv

Lub Caij emf Nws tshwm sim, xws li nyob rau hauv cov kev sib cuag semiconductor anode thiab cathode rau lawv hlau qhov chaw pab mus cuag cov sab nraud voltage qhov chaw. Qhov no emf vim internal PKK. Internal YOG tsis tsim, nyob rau hauv sib piv rau cov sab nraud teb nyob rau hauv lub qhov chaw uas lwm tus cov kev sib cuag conductors, i.e. Nws tsis cuam tshuam rau cov lus tsa suab ntawm them hais sab nraum lub conductors. Siv cov kev faib n-semiconductor / hlau / p-semiconductor yog txaus paub thiab yog siv, piv txwv li, ib tug thermoelectric Peltier module. Lub magnitude ntawm lub emf xws li ib tug qauv ntawm chav tsev kub yuav ncav cuag qhov tseem ceeb ntawm qhov kev txiav txim ntawm 0.4 - 0.6 Volt [5, p. 459; 2, p. 552]. Liaj teb uas nyob hu yog qhia nyob rau hauv xws li ib tug txoj kev uas lawv thawb electrons counterclockwise nyob rau hauv lub voj, i.e. ua nyob rau hauv kev hais kwv txhiaj nrog rau lwm qhov chaw. Lub electrons tsa lub zog ntawm qhov nruab nrab absorbing lub tshav kub ntawm Peltier.

Internal YOG tsob vim cov diffusion ntawm electrons nyob rau hauv kev sib cuag qhov chaw ntawm lub electrodes thiab cov tshuaj, on qhov tsis tooj, pushes electrons nyob rau hauv lub clockwise kev taw qhia nyob rau hauv lub voj. Xws li lub suab ntawm electrons nyob rau hauv lub caij counterclockwise nyob rau hauv cov mob yuav tsum muab sau ua ke Peltier tshav kub. Tab sis vim hais tias cov kev hloov ntawm electrons los ntawm cov cathode rau hauv cov tshuaj thiab cov tshuaj nyob rau hauv lub anode yog tas nrog los ntawm ib tug endothermic cov tshuaj tiv thaiv generating hydrogen thiab oxygen, lub tshav kub ntawm Peltier yog tsis tau tso tawm rau hauv lub nruab nrab, thiab yog los txo cov endothermic nyhuv, i.e. zoo li "conserved" nyob rau hauv lub enthalpy ntawm tsim ntawm hydrogen thiab oxygen. Kom paub meej, saib. Nyob rau hauv Annex №2 peb ib feem ntawm qhov tsab xov xwm.

muaj (electrons thiab ions) txav mus rau hauv Caij Circuit Court tsis kaw paths, tsis tau them nqi nyob rau hauv lub caij yog tsis tsiv nyob rau hauv ib tug kaw Circuit Court. Txhua electron anode tau los ntawm cov tshuaj (nyob rau hauv lub chav kawm ntawm oxidation ntawm OH- ions rau oxygen molecules), thiab dhau los ntawm ib tug sab nraud Circuit Court mus rau lub cathode, yog volatilized ua ke nrog hydrogen molecules (nyob rau hauv tus txheej txheem ntawm rov qab los ntawm ions H +). Ib yam li ntawd ions OH- thiab H + tsis tsiv mus nyob rau ib lub kaw Circuit Court, tab sis tsuas yog cov coj electrode, thiab ces qhuav nyob rau hauv daim ntawv ntawm cov molecular hydrogen thiab oxygen. Xws li thiab lub ions thiab electrons txhua tsiv nyob rau hauv nws cheeb tsam nyob rau hauv lub accelerating teb ntawm tej kev lav ris, thiab qhov kawg ntawm txoj kev, thaum lawv mus txog ntawm qhov chaw ntawm lub electrode ua ke nyob rau hauv lub molecule, hloov tag nrho cia lub zog - lub zog ntawm ib tug tshuaj daim ntawv cog lus, thiab tawm hauv lub voj!

Tag nrho cov sab hauv qhov chaw ntawm emf Caij, txo cov nqi sab nraud qhov chaw rau dej electrolysis. Yog li, lub tshav kub ntawm ambient absorbing ntsiab thaum lub sij hawm nws lub lag luam kom muaj diffusion ntawm tej kev lav ris, yog los txo tus nqi ntawm cov sab nraud qhov chaw, i.e., Nws tsub kom lub electrolysis efficiency.

Electrolysis dej tsis muaj lwm qhov chaw.

Nyob rau hauv kev rov xyuas dua cov txheej txheem uas tshwm sim nyob rau hauv lub caij qhia nyob rau hauv Daim duab. 1, ib tug sab nraud qhov chaw tsis yog tsis noj rau hauv tus account. Piv txwv hais tias cov sab hauv kuj yog sib npaug zos rau lawm thiab ib tug voltage ntawm 0. ntawd Evnesh Caij electrodes yog shorted mus rau ib tug passive load (saib Fig. 5). Nyob rau hauv cov ntaub ntawv no, cov kev taw qhia thiab magnitude ntawm tej kev lav ris teb sawv ntawm lub interface nyob rau hauv lub ntsiab nyob li qub.

Daim duab. 5. Tsis txhob Evnesh (Fig. 1) xws li passive load RL.

Txiav txim seb tus mob ntawm txawj tam sim no txaus nyob rau hauv no lub caij. Hloov cov Gibbs tej zaum, raws li cov mis (1) ntawm Annex №1 ntawm peb ib feem ntawm qhov tsab xov xwm:

Δ G arr = (Δ H arr - n) + Q mod

Yog hais tias P> Δ H + Q mod mod = 284,5 - 47.2 = 237.3 (kJ / mol) = 1.23 (eV / molecule)

lub Δ G arr <0 thiab txawj txoj kev yog tau.

Peb yuav xav txog ntxiv tias hais hydrogen tiam tshuaj tiv thaiv no tshwm sim nyob rau hauv ib tug acidic nruab nrab (electrode tej zaum ntawm 0 volts), thiab oxygen nyob rau hauv ib tug alkaline (electrode peev xwm ntawm 0.4 volts). Tej electrode potentials muab ib tug nyias nyias (5, Daim duab. 5), cov voltage uas qhov no yuav tsum tau 0,83 volts. Xws li lub zog yuav tsum rau cov tsim ntawm hydrogen thiab oxygen yog txo los ntawm 0.83 (eV / molecule). Ces tus mob ntawm tau ntawm txawj txheej txheem yuav:

P> 1.23 - 0.83 = 0.4 (eV / molecule) = 77.2 (kJ / mol) (2)

Peb pom tau tias lub zog barrier ntawm lub hydrogen thiab oxygen molecules avoidable thiab tsis siv ib lwm voltage qhov chaw. Xws li txawm nyob rau hauv n = 0.4 (eV / molecule), i.e. thaum lub puab electrode HPDC 0.4 volts, lub caij yuav nyob rau hauv ib lub xeev ntawm dynamic equilibrium, thiab tej (txawm me me) kev hloov ntawm cov tshuav nyiaj li cas tej yam kev mob yuav ua rau qhov tam sim no nyob rau hauv lub Circuit Court.

Lwm lub chaw khuam siab rau tus tshua nyob rau electrodes yog qhov ua kom muaj zog, tab sis nws yog tshem tawm los ntawm lub qhov nyhuv, tshwm sim vim cov smallness ntawm cov kis ntawm tus electrodes thiab cov tshuaj [7, p. 147-149].

Yog li, nyob rau hauv lub hauv paus ntawm lub zog xav txog kev teem, peb xaus uas txawj tam sim no nyob rau hauv lub caij qhia nyob rau hauv Daim duab. 5, nws yog ua tau. Tab sis li cas lub cev yog vim li cas yuav ua rau qhov no tam sim no? Cov yog vim li cas muaj raws li nram qab no:

1. Qhov ntau yam ntawm txoj kev hloov ntawm electrons los ntawm cov cathode mus rau hauv lub tshuaj ntau dua li qhov muaj tseeb ntawm txoj kev hloov los ntawm lub anode rau hauv cov tshuaj, txij li thaum n-semiconductor cathode muaj ib tug ntau dawb electrons nrog ib tug high school cov muaj zog, thiab lub p-semiconductor anode - tsuas yog "qhov", thiab cov "qhov" yog nyob rau ntawm ib lub zog theem hauv qab no lub cathode electrons;

2. Cov membrane yog txaus siab nyob rau hauv lub cathode qhov chaw ntawm ib tug acidic ib puag ncig, thiab nyob rau hauv lub anode - alkaline. Nyob rau hauv cov ntaub ntawv ntawm inert electrodes, qhov no ua rau lub fact tias ib tug cathode electrode tej zaum yuav loj dua lub anode. Thiaj li, electrons yuav tsum tsiv mus los ntawm ib tug sab nraud Circuit Court los ntawm cov anode mus rau lub cathode;

3. Cov nto them nyiaj ntawm cov polyelectrolyte kev daws teeb meem uas tshwm sim taus vim yog lub Donnan nyhuv, tsim nyob rau electrode / tov teb xws li hais tias lub teb nyob rau cathode txhawb electron tawm los ntawm lub cathode rau hauv cov tshuaj, thiab lub teb ntawm cov anode - electron nkag mus rau hauv lub anode los ntawm cov tshuaj;

4. tshuav nyiaj li cas rau pem hauv ntej thiab rov qab tshua nyob rau electrodes (pauv currents) biased mus rau H + ions direct txo tshua nyob rau cathode thiab oxidation ntawm OH- ions nyob rau anode, txij li thaum lawv nrog tsim ntawm roj (H2 thiab O2) muaj peev xwm ntawm yooj yim tawm hauv cov tshuaj tiv thaiv cheeb tsam (Le Chatelier lub hauv paus ntsiab lus).

Sim kawm.

Rau ntau kev luj xyuas ntawm tus voltage thoob plaws lub load los ntawm cov Donnan nyhuv, ib tug xyaum ua tej yam twb tau nyob rau hauv uas lub cathode Caij muaj lub tshuab txais carbon nrog lub txheej graphite electrode thiab ib tug anode - ib tug sib tov ntawm tshuab txais carbon thiab anion cob AB-17-8 nrog lub txheej graphite electrode. Ntsha - aqueous NaOH tshuaj, anode thiab cathode tej qhov chaw muaj sib cais los ntawm ib tug hluavtaws felt. Nyob rau qhib lwm electrodes ntawm no lub caij muaj ib tug voltage ntawm txog 50 MV. Thaum kev cob cog rua rau lub caij ntawm cov sab nraud load 10 ohm tsau tam sim no uas hais txog 500 microamps. Thaum lub ambient kub nce los ntawm 20 mus rau 30 0C voltage rau lwm electrode ntau zog rau 54 MV. Ua lub voltage ntawm lub ambient kub qhia hais tias qhov uas emf yog diffusion, i.e. thermal tsab ntawv tsa suab ntawm tus hais.

Rau ntau kev luj xyuas ntawm tus voltage thoob plaws lub load ntawm lub puab HPDC hlau / semiconductor xyaum ua tej yam twb tau soj xyuas nyob rau hauv uas lub cell cathode muaj hluavtaws graphite hmoov nrog lub txheej graphite electrode thiab ib tug anode - ib tug hmoov ntawm boron carbide (B4C, p-semiconductor) nrog cov txheej graphite electrode. Ntsha - aqueous NaOH tshuaj, anode thiab cathode tej qhov chaw muaj sib cais los ntawm ib tug hluavtaws felt. Nyob rau qhib lwm electrodes ntawm lub caij voltage yog hais txog 150 MV. Thaum txuas rau lwm load rau lub caij 50 kOhm voltage tshem tawm mus rau 35 MV., Xws ib tug muaj zog voltage nco vim cov uas tsis muaj intrinsic boron carbide thiab, raws li ib tug tshwm sim, ib tug siab nrog kuj Caij. Kev tshawb nrhiav voltage tiv tiag kub rau ib tug keeb ntawm xws qauv yog tsis nqa tawm. Qhov no yog vim lub fact tias, rau ib tug semiconductor, nyob ntawm seb nws tshuaj nyob tus yeees, degree ntawm doping thiab lwm yam khoom, qhov kub sov tso nyob rau hauv ntau txoj kev muaj feem xyuam rau nws Fermi theem. Xws li kub ntxim rau emf Caij (nce los yog txo), nyob rau hauv cov ntaub ntawv no yog nyob rau cov ntaub ntawv siv, yog li no tsis yog indicative xyaum ua tej yam.

Thaum no tus taw tes nws txuas ntxiv lwm xyaum ua tej yam nyob rau hauv uas cell cathode yog ua los ntawm ib tug sib tov ntawm tshuab txais carbon hmoov thiab KU-2-8 nrog lub txheej stainless steel electrode thiab cov anode los ntawm ib tug sib tov ntawm tshuab txais carbon hmoov thiab anion cob AB-17-8 rau lwm electrode los ntawm stainless hlau. Ntsha - aqueous tov ntawm NaCl, lub anode thiab cathode tej qhov chaw muaj sib cais los ntawm ib tug hluavtaws muaj. Sab nraud electrodes ntawm no lub caij nrog Lub kaum hli ntuj 2011 yog muaj peev xwm kom luv luv-Circuit Court lub passive ammeter. Tam sim no uas qhia tau hais tias ib tug ammeter, hais txog ib hnub tom qab tig, poob los ntawm 1 ma - mus txog rau 100 mkA (uas yog thaj vim lub polarization ntawm lub electrodes), thiab txij thaum ntawd ntau tshaj ib xyoo tsis hloov.

Nyob rau hauv cov tswv yim thwmsim piav saum toj no nyob rau hauv kev twb kev txuas nrog cov zoo tshaj ntaub ntawv inaccessibility tau tau tshuam qis tshaj raws tau. Nyob rau hauv tas li ntawd, yuav tsum paub hais tias ib feem ntawm tag nrho cov sab hauv emf Caij ib txwm noj rau kev tswj cov electrode cov tshuaj tiv thaiv (zus tau tej cov hydrogen thiab oxygen) thiab tsis tau ntsuas nyob rau hauv lub sab nraud Circuit Court.

Xaus.

Summing li, peb yuav xaus hais tias xwm tso cai rau peb kom peb hloov thermal zog rau hauv pab zog los yog ua hauj lwm, thaum siv raws li ib tug "rhaub" ib puag ncig thiab tsis muaj ib tug "tub yees". Yog li Donnan nyhuv thiab nrog YOG hloov dua siab tshiab thermal lub zog ntawm lub them hais nyob rau hauv lub hluav taws xob field zog DEL li cov endothermic cov tshuaj tiv thaiv tshav kub yog hloov dua siab tshiab rau hauv tshuaj muaj zog.

Xam tias yog hu caij kov tshav kub ntawm qhov nruab nrab thiab dej, thiab allocates hluav taws xob lub hwj chim, hydrogen thiab cov pa! Ntxiv mus, tus txheej txheem ntawm lub zog noj thiab kev siv ntawm hydrogen raws li ib tug roj, thiab cov dej rov qab mus rau lub tshav kub nruab nrab!

Part 3 ntawm lub Annex.

Qhov no yog ib feem yog ntxiv los sib tham Donnan equilibrium nyhuv, nyob lub hlws ris ntawm lub puab HPDC hlau / semiconductor thiab Peltier tshav kub nyob rau hauv redox tshua thiab electrode potentials nyob rau hauv lub caij.

Donnan tej zaum (Appendix №1)

Xav txog cov mechanism ntawm tshwm sim ntawm Donnan muaj peev xwm rau polyelectrolyte. Tom qab dissociation polyelectrolyte counterions pib nws me me, los ntawm diffusion, tawm hauv lub ntim nyob los ntawm cov macromolecule. Directional diffusion ntawm counterions ntawm me me volume polyelectrolyte macromolecules nyob rau hauv lub kuab yog vim muaj zog concentration nyob rau hauv lub ib thooj ntawm cov macromolecule li piv nrog rau tus so ntawm cov tshuaj. Ntxiv mus, yog hais tias, piv txwv li, me me counterions tsis zoo them, qhov no los tau nyob rau hauv uas lub puab feem ntawm lub macromolecule yog zoo them, thiab cov tshuaj no sai li sai tau nyob ib sab mus rau lub ntim ntawm lub macromolecule - tsis zoo. Xws li nyob ib ncig ntawm ib tug zoo them macroion volume, muaj yog ib tug zoo ntawm "ion cua" ntawm lub me me counter-ions - tsis zoo them. Txiav ionic cua xwb txoj kev loj hlob tshwm sim thaum lub electrostatic teb ntawm lub ion volume macroion cua thiab balances lub thermal diffusion ntawm me me counterions. Cov uas ua equilibrium tej zaum qhov sib txawv ntawm cov cua thiab lub ionic macroions yog Donnan peev xwm. Donnan tej zaum kuj yog raug xa mus rau raws li daim nyias nyias muaj peev xwm, vim hais tias ib tug zoo li qhov teeb meem no tshwm sim rau ib tug semipermeable membrane, piv txwv li, thaum nws cais lub ntsha tov uas muaj ions ntawm ob hom - muaj peev xwm thiab tsis muaj peev xwm sawv ntawm dua therethrough ntawm qhov kev ntshiab kuab.

Donnan tej zaum yuav suav hais tias ua ib limiting cov ntaub ntawv ntawm lub diffusion tej zaum, thaum lub kev mus ncig ntawm ib qho ntawm lub ions (nyob rau hauv cov ntaub ntawv no macroion) yog pes tsawg. Ces, raws li [1, p. 535], noj them nyiaj ntawm counter sib npaug zos rau ib tug:

E d = (RT / F) haujlwm uas yog COy ( a1 / a2), qhov chaw uas

Ed - Donnan tej zaum;

R - universal roj qhov;

T - thermodynamic kub;

F - Faraday qhov;

a1, a2 - counter-kev ua si nyob rau hauv kev sib cuag theem.

Nyob rau hauv no neeg, nyob rau hauv daim nyias nyias cais poliosnovaniya kev daws teeb meem (pH = Lg ib tug 1 = 14) thiab polyacid (pH = Lg ib tug 2 = 0), Donnan tej zaum nyob rau lub membrane ntawm chav tsev kub (T = 300 0 K) yuav tsum:

E d = (RT / F) (Lg ib tug 1 - Lg ib tug 2) haujlwm uas yog COy (10) = (8,3 * 300/96500 ) * (14 - 0) * haujlwm uas yog COy (10) = 0.83 volts

Donnan tej zaum yuav tsub kom nyob rau hauv ncaj qha kev faib ua feem rau kub. Rau diffusion ntawm lub electrochemical cell Peltier tshav kub yog tib tug qhov chaw rau zus tau tej cov pab ua hauj lwm, nws tsis yog li ntawd tej ntsiab emf tsub kom nrog ua kub. Nyob rau hauv diffusion cell rau zus tau tej cov chaw ua hauj lwm, Peltier tshav kub yog ib txwm coj los ntawm cov ib puag ncig. Thaum tam sim no tsev los ntawm lub EDL tsim Donnan nyhuv, nyob rau hauv ib lub tsheb coinciding nrog lub zoo cov kev taw qhia ntawm lub tshav pob ntawm tej kev lav ris (i.e., thaum lub tshav pob ntawm tej kev lav ris ua zoo ua hauj lwm), Thaum tshav kub kub yog absorbed los ntawm cov ib puag ncig rau tus zus tau tej cov no daim ntawv.

Tab sis lub diffusion caij yog ib tug tas mus li thiab unidirectional hloov nyob rau hauv ion concentration, uas thaum kawg ua rau cov equalization ntawm concentration thiab siv ceev xwmphem qhia diffusion, tsis zoo li equilibrium Donnan, wherein, nyob rau hauv ib rooj plaub ntawm txia quasistatic currents ion concentration, ib zaug thaum mus txog ib tug tej yam muaj nuj nqis, tseem unchanged .

Daim duab. 2 qhia tau hais tias ib daim duab ntawm lub redox potentials ntawm lub tshua ntawm hydrogen thiab cov pa thaum hloov lub acidity ntawm cov tshuaj. Lub daim ntawv qhia tau hais tias lub electrode peev xwm ntawm cov pa tsim tshuaj tiv thaiv nyob rau hauv lub qhaj ntawv ntawm OH- ions (1.23 volts nyob rau hauv ib tug acidic ib puag ncig) yog txawv los ntawm lub tib lub tej zaum ntawm siab concentration (0.4 volts nyob rau hauv ib tug alkaline nruab nrab) ntawm 0,83 volts. Ib yam li ntawd, tus electrode tej zaum ntawm hydrogen-txoj kev tshuaj tiv thaiv nyob rau hauv lub qhaj ntawv ntawm H + (-0.83 volts nyob rau hauv alkaline nruab nrab) yog txawv los ntawm lub tib lub tej zaum ntawm siab concentration (0 V nyob rau hauv ib tug acid nruab nrab), kuj nyob rau ntawm 0,83 volts [4. 66-67]. Xws li tshwm tag uas 0,83 volts yog yuav tsum tau nyob rau hauv thiaj li yuav tau ib tug siab concentration ntawm cov dej nyob hauv lub duas paub ions. Qhov no txhais tau tias 0,83 volts yog yuav tsum tau rau ib tug loj ntawm nruab nrab dissociation dej lwg me me mus rau hauv H + thiab OH- ions. Yog li, yog hais tias tus membrane yog txaus siab nyob rau hauv peb Caij cathode chaw acidic nruab nrab thiab nyob rau hauv ib tug alkaline anodic, lub voltage yuav ncav cuag nws cov DEL 0,83 volts, uas yog nyob rau hauv zoo daim ntawv cog lus nrog rau cov theoretical suav hais ua ntej lawm. Qhov no voltage muab ib tug high school cov conductivity qhov chaw tej kev lav ris nyias nyias los ntawm dej dissociation rau hauv ions nyob hauv nws.

Daim duab. 2. Daim duab redox cov tshuaj tiv thaiv potentials

decomposition ntawm dej, thiab H + ions thiab OH- rau hauv hydrogen thiab oxygen.

YOG thiab Peltier tshav kub kub (Appendix №2)

"Ua kom muaj qhov Peltier nyhuv yog tias qhov nruab nrab lub zog ntawm tus nqi muaj (rau definiteness electrons) muab kev koom tes nyob rau hauv lub hluav taws xob conductivity nyob rau hauv ntau yam conductors ntawm txawv ... Nyob rau hauv txoj kev hloov los ntawm ib tug neeg xyuas pib mus rau lwm lub electron los yog kis tshaj hwj chim daim phiaj los yog pab ib tug tsis muaj zog nyob rau hauv nws cov nyiaj them (nyob ntawm seb tam sim no cov kev taw qhia).

Daim duab. 3. Cov Peltier ntxim rau cov kev sib cuag hlau thiab lub semiconductor n-: ԐF - Fermi theem; ԐC - rau hauv qab ntawm lub conduction qhab ntawm lub semiconductor; ԐV - valence band; I - zoo coj ntawm tam sim no; voj voog nrog sub qhia schematically electrons.

Nyob rau hauv rooj plaub thawj nyob ze cov kev sib cuag yog tso tawm, thiab lub thib ob - qhov thiaj li hu ua absorbed .. Peltier tshav kub. Piv txwv li, nyob rau cov kev sib cuag semiconductor - hlau (Daim duab 3) lub zog ntawm cov electrons uas kis los ntawm lub n-hom semiconductor rau hlau (sab laug kov) yog ho ntau dua li cov Fermi zog ԐF. Yog li ntawd, lawv yog ua txhaum lub thermal equilibrium nyob rau hauv cov hlau. Equilibrium yog rov qab los raws li ib tug tshwm sim ntawm collisions, nyob rau hauv uas thermalized electrons, muab tshaj zog crystalline. daim phiaj. Lub semiconductor hlau (txoj cai kov) yuav kis tau tsuas yog tus feem ntau nquag electrons, yog li ntawd electron roj nyob rau hauv cov hlau cools. Nyob rau kho tshiab ntawm lub equilibrium faib ntawm oscillation zog noj lattice "[2, p. 552].

Yuav kom hu mus rau lub hlau / p-semiconductor teeb meem no yog zoo sib xws. Vim hais tias p-conductivity semiconductor qhov muab nws cov valence qhab uas yog hauv qab no lub Fermi theem, ces tus hu yuav tsum txias, nyob rau hauv uas electrons ntws los ntawm cov p-semiconductor rau tus hlau. Peltier tshav kub tso tawm los yog absorbed los ntawm cov kev sib cuag ntawm ob conductors, vim zus tau tej cov tsis zoo los yog zoo ntawm lub hauv YOG.

Muaj nyob rau hauv rau sab laug hu kis (Fig. 3), nyob rau hauv uas lub Peltier tshav kub faib, ib tug electrolytic cell, piv txwv li, aqueous NaOH tshuaj (Daim duab 4) thiab hlau semiconductor thiab n-cia nws yuav sib inert.

Daim duab. 4. Cov sab laug hu n-semiconductor thiab cov hlau qhib thiab muab tso rau hauv cov kis ntawm cov ntsha tov. Designations yog tib yam li nyob rau hauv Daim duab. 3.

Vim hais tias, thaum tam sim no tsev «Kuv», lub semiconductor ntawm n-electrons nyob rau hauv ntau dua lub zog txog cov tshuaj tshaj los ntawm cov tshuaj nyob rau hauv cov hlau, qhov no tshaj zog (tshav kub ntawm Peltier) yuav tsum sawv ntsug nyob rau hauv lub cell.

Tus tam sim no los ntawm lub cell yuav yuav tsuas yog ib cov ntaub ntawv ntawm txia therein electrochemical tshua. Yog hais tias lub exothermic cov tshuaj tiv thaiv nyob rau hauv lub cell, lub Peltier tshav kub tso tawm nyob rau hauv lub cell, raws li ntau nws muaj tsis pom qhov twg mus. Yog hais tias cov tshuaj tiv thaiv nyob rau hauv lub cell - endothermic, lub Peltier tshav kub yog tawg ntho los yog tej pab kom txawm peem rau cov endothermic nyhuv, piv txwv li, tsim tau ib cov tshuaj tiv thaiv cov khoom. Nyob rau hauv qhov kev piv txwv, tag nrho cov cell cov tshuaj tiv thaiv: 2H2O → 2H2 ↑ + O2 ↑ - endothermic, li ntawd, lub tshav kub (zog) cov Peltier yog los tsim molecules thiab H2 O2, yog tsim nyob rau hauv lub electrodes. Yog li, peb tau hais tias lub tshav kub ntawm Peltier xaiv nyob rau hauv nruab nrab nyob rau hauv txoj cai n-hu semiconductor / hlau yog tsis tau tso tawm rov qab mus rau hauv lub cheeb tsam, thiab muab cia rau hauv daim ntawv ntawm cov tshuaj zog ntawm hydrogen thiab oxygen molecules. Obviously, lub lag luam ntawm cov sab nraud voltage qhov chaw yog noj rau lub electrolysis dej, nyob rau hauv rooj plaub no yuav tsum tau me me tshaj nyob rau hauv cov ntaub ntawv ntawm tib yam electrodes, ua tsis muaj tshwm sim ntawm cov Peltier nyhuv ..

Txawm li cas los ntawm lub zog ntawm cov electrodes, lub electrolytic cell nws tus kheej muaj peev xwm nqus los yog tsim thaum tshav kub kub thaum dhau los ntawm lub Peltier tam sim no thereto. Lub quasi-zoo li qub tej yam kev mob, lub peev xwm kev hloov ntawm cov Gibbs hlwb [4, p. 60]:

Δ G = Δ H - T Δ S, qhov twg

Δ H - enthalpy kev hloov ntawm cov cell;

T - thermodynamic kub;

Δ S - hloov nyob rau hauv lub entropy ntawm lub cell;

Q = - T Δ S - Thaum tshav kub kub ntawm lub Peltier cell.

Rau ib hydrogen-pa electrochemical cell ntawm T = 298 (K), qhov kev hloov nyob rau hauv enthalpy ΔHpr = - 284.5 (kJ / mol) [8, p. 120], qhov kev hloov nyob rau hauv lub Gibbs tej zaum [4. ib tug. 60]:

ΔGpr = - zFE = 2 * 96485 * 1.23 = - 237.3 (kJ / mol), qhov chaw uas

z - tus naj npawb ntawm electrons ib molecule;

F - Faraday qhov;

E - emf cell.

yog li ntawd

Q po = - T Δ S po = Δ G etc. - Δ H etc. = - 237,3 + 47,2 = 284,5 (kJ / mol)> 0,

ie hydrogen-pa electrochemical cell generates tshav kub nyob rau hauv lub Peltier ib puag ncig, thaum kev txhim kho nws entropy thiab tej nws. Ces, nyob rau hauv lub rov qab tus txheej txheem, lub electrolysis ntawm dej, uas yog cov ntaub ntawv nyob rau hauv peb tus yam ntxwv, Peltier tshav kub Q mod = - Q po = - 47.3 (kJ / mol) ntawm lub ntsha yuav absorbed los ntawm cov ib puag ncig.

Txhais P - Peltier tshav kub coj los ntawm cov ib puag ncig nyob rau hauv txoj cai n-hu semiconductor / hlau. Lub tshav kub P> 0 yuav tsum sawv ntsug nyob rau hauv lub cell, tab sis vim hais tias decomposition dej nyob rau hauv lub cell endothermic cov tshuaj tiv thaiv (Δ H> 0), lub Peltier tshav kub P yog pab kom txawm peem rau lub thermal nyhuv ntawm cov tshuaj tiv thaiv:

Δ G arr = (Δ H arr - n) + Q mod                                                                        (1)

Mod Q nyob tsuas yog nyob rau nyob tus yeees ntawm cov ntsha, txij li thaum Nws yog ib tug yam ntxwv ntawm lub electrolytic cell nrog inert electrodes, thiab n yog nyob tsuas yog nyob rau hauv lub electrode cov ntaub ntawv.

Kab zauv (1) qhia tau hais tias lub tshav kub ntawm Peltier P thiab Peltier sov mod Q, yog cov ntau lawm pab ua hauj lwm. Xws li Peltier tshav kub noj tam sim ntawd los ntawm qhov nruab nrab cov nqi ntawm ib tug sab nraud hwj chim qhov twg los yuav tsum tau rau electrolysis. Ib tug teeb meem nyob qhov twg lub tshav kub nruab nrab yog ib qhov chaw ntawm lub zog rau zus tau tej cov pab ua hauj lwm, yog cov yam ntxwv ntawm diffusion, raws li zoo raws li rau ntau electrochemical hlwb, piv txwv xws li hais qhia nyob rau hauv [3, p. 248 - 249].

References

1. Gerasimov Ya. I. chav kawm ntawm lub cev Science News for KIDS. Tutorial: Rau universities. V 2 t. T.II. - 2nd ed .. - M.: Chemistry, Moscow, 1973. - 624 p.
2. Dashevskiy 3. M. Peltier nyhuv. // Lub Cev encyclopedia. Nyob rau hauv 5 m. T. III. Magneto - Poynting theorem. / Ch. Ed. A. M. Prohorov. Ed. suav. DM Alekseev, A. M. Baldin, AM Bonch-Bruevich, A. Borovik-Romanov thiab lwm leej lwm tus -. M.: Great Lavxias teb sab Encyclopedia, 1992. - 672 p. - ISBN 5-85270-019-3 (3 m.); ISBN 5-85270-034-7.
3. Krasnov KS cev Science News for KIDS. Nyob rau hauv 2 phau ntawv. Vol. 1. Qauv ntawm teeb meem. Thermodynamics: Proc. rau cov tsev kawm ntawv; KS Krasnov, N. K. Vorobev, I. li al Godnev -. 3rd ed .. - M.: Siab. wk, 2001. -. 512. - ISBN 5-06-004025-9.
4. Krasnov KS cev Science News for KIDS. Nyob rau hauv 2 phau ntawv. Vol. 2. Electrochemistry. Tshuaj kinetics thiab catalysis: Proc. rau cov tsev kawm ntawv; KS Krasnov, NK Vorobyov I. N. Godnev li al. -3 ed., Rev. - M.: Siab. wk, 2001. -. 319. - ISBN 5-06-004026-7.
5. Sivukhin DV general chav kawm ntawm physics. Tutorial: Rau universities. Nyob rau hauv 5 m. T.III. Hluav taws xob. - 4 ed, stereotypes .. - M.: FIZMATLIT; Publishing tsev ntawm tus MIPT, 2004. - 656 p. - ISBN 5-9221-0227-3 (3 m.); 5-89155-086-5.
6. Tager A. A. cev Science News for KIDS ntawm polymers. - M.: Chemistry, Moscow, 1968. - 536 p.
7. Vetter K. Electrochemical kinetics, txhais los ntawm lub German lus nrog tus neeg sau txoj kev hloov mus rau lub Lavxias teb sab tsab, edited los ntawm corr. USSR Academy ntawm Sciences prof. Kolotyrkin ym - M.: Chemistry, Moscow, 1967. - 856 p.
8. P. Atkins cev Science News for KIDS. Nyob rau hauv 2 v. T.I., txhais los ntawm lus Askiv ntawm tus kws kho mob ntawm tshuaj sciences Butin KP - M.: Mir, Moscow, 1980. - 580 p.