Electrochemical reactions ba bere a nnuru ahoɔden dan anyinam ahoɔden anaasɛ nea ɛne no bɔ abira denam electron transfer so wɔ electrode ne electrolyte ntam no. Saa nneyɛe yi kɔ so wɔ nhyehyɛe biara a anyinam ahoɔden ma nnuru sesa anaa baabi a nnuru a ɛyɛ adwuma ma anyinam ahoɔden ba no mu.
Nneɛma a ɛho hia .
Electrochemical reactions hwehwɛ nneɛma atitiriw abiɛsa a ɛbom yɛ adwuma. Electron conductor yɛ electrode wɔ baabi a reactions si wɔ soro. ionic conductor-a mpɛn pii no ɛyɛ electrolyte solution a ions a wɔapete-ma charge a ɛsen fa electrodes ntam. Ɔmansin a edi mũ na ɛka saa nneɛma yi bom, na ɛma ɛlɛtrɔnik no tumi fa abɔnten kwan bi so.
Adeyɛ no ba pɔtee wɔ electrode-electrolyte interface no so, wɔ angstroms kakraa bi pɛ mu fi conductor no ani. Saa beae teateaa yi wɔ hɔ efisɛ ɛlɛtrɔnik da so ara tu wɔ ɛlɛtrɔnik nhama te sɛ dade mu nkutoo, bere a ions soa ahoɔden fa electrolyte no mu.
Bere a nneyɛe a ɛba ara kwa no ma ahoɔden ba no .
Galvanic nkwammoaa da electrochemical reactions a ɛba ara kwa ma ɛyɛ anyinam ahoɔden adi. Wɔ saa nhyehyɛe ahorow yi mu no, oxidation si wɔ anode no so bere a reduction ba wɔ cathode no so. Nnuru tumi mu nsonsonoe a ɛwɔ saa fã abien yi-reactions no ma electron fa abɔnten circuit no mu.
Battery a ɛba no yɛ saa adeyɛ a ɛba ara kwa yi ho nhwɛso. Sɛ wode forklift batere di dwuma a, nnuru a ɛyɛ adwuma wɔ electrode nneɛma ne electrolyte ntam no ma ɛlɛtrɔnik a ɛma motor no nya ahoɔden no fi hɔ. Lead-Acid variants Fa lead dioxide ne sponge lead mprɛte a wɔde ahyɛ sulphuric acid mu di dwuma, a electrochemical reaction no dane nnuru ahoɔden a wɔakora so no kɔ anyinam ahoɔden a ɛho hia ma nneɛma a wɔde ma so no mu.
Daniell nkwammoaa no kyerɛkyerɛ nnyinasosɛm no mu pefee. Zinc metal oxidize wɔ electrode biako mu, na ɛma ɛlɛtrɔnik a ɛsen fa nhama mu no ma kɔbere ions so tew wɔ electrode foforo no so. Saa ɛlɛtrɔnik nsuo yi yɛ anyinam ahoɔden, a ɛkɔ so kɔsi sɛ reactants no bɛsa anaasɛ nhyehyɛeɛ no adu pɛpɛɛpɛ.
Bere a abɔnten so ahoɔden ma nneyɛe kɔ so no .
Electrolytic cells gyina hɔ ma tebea a ɛne no bɔ abira-electrochemical reactions a ɛnyɛ nea ɛba ara kwa nanso ɛhwehwɛ sɛ wɔde voltage a wɔde di dwuma kɔ so. Abɔnten so anyinam ahoɔden ahoɔden a ɛnyɛ{2}}nnuru a ɛba bere biara mu.
Sɛ wobɔ batere a wotumi de hyɛ mu bio a, ɛda nnyinasosɛm yi adi. Sɛ wode lead-acid battery bata charger ho a, voltage a wɔde di dwuma no dannan discharge reactions no. Lead sulfate dan kɔ kɔbere dioxide ne sponge kɔbere mu, bere a sulfuric acid dodow kɔ soro wɔ electrolyte no mu. Electrical energy input no san kyekye nnuru tumi a akyiri yi ɛbɛma wo mfiri no anya ahoɔden no.
Nsu mu electrolysis ma nhwɛso foforo a emu da hɔ. Sɛ wɔde voltage a ɛdɔɔso di dwuma wɔ electrode ahorow a ɛwɔ nsu a ɛwɔ nsu mu no mu a, ɛpaapae H2O molecule ahorow mu ma ɛyɛ hydrogen ne oxygen mframa. Ɛsɛ sɛ voltage a wɔhwehwɛ no boro nnuru tumi mu nsonsonoe a ɛda oxidation ne reduction half-reactions ntam no so.
Mfiridwuma mu anyinam ahoɔden a wɔde anyinam ahoɔden yɛ no gyina saa adeyɛ a wɔhyɛ nkurɔfo ma wɔyɛ so yi so. Electric current de metal ions fi solution so kɔ ade a ɛma conductive so, na ɛma ahobammɔ anaa afɛfɛde kata so denam electrochemical adeyɛ a ɛrensi a ahoɔden a wɔde di dwuma wom so.
Ɔhyew ne adeyɛ tebea horow .
Electrochemical reactions kyerɛ ɔhyew ho nkate a ɛho hia. Battery dodow no ara yɛ adwuma yiye wɔ 0℃ne 45℃ntam , a adwumayɛ sɛe wɔ saa kwan yi akyi. Awɔw mu hyew ma emu ahoɔden a ɛwɔ mu no yɛ kɛse, na ɛma ion a ɛkɔ fam no brɛ ase denam electrolyte no so na ɛtew tumi a ɛba no so. A lead-acid battery hwere 50% tumi wɔ-20℃, bere a lithium-ion batere kɔ so yɛ adwuma yiye a tumi 20% pɛ na ɛyera wɔ ɔhyew koro no ara mu.
Ɔhyew ma nnuru sɛe ntɛmntɛm nanso ebetumi nso ayɛ ade a ɛma nneɛma yɛ adwuma ntɛmntɛm wɔ anohyeto ahorow a ahobammɔ wom mu. Nanso, ɔhyew a ɛboro so a ɛboro digrii 60 no wɔ asiane mu sɛ ɔhyew guan wɔ lithium batere mu, baabi a exothermic reactions bɛyɛ ne ho-akɔ so na asiane wom. Ɔhyew-dependent nature kyerɛ sɛ electrochemical reactions no ba ntɛmntɛm wɔ ɔhyew a ɛkɔ fam a ion mobility kɔ so yɛ kɛse a ɛnkanyan porɔwee.
Electrolyte concentration nya reaction rates so nkɛntɛnso kɛse. Wɔ kɔbere-Acid batere mu no, sulphuric acid no mu tumi a ɛtwe ade ba fam pɔtee no sesa bere a wɔreyi no, efi bɛyɛ 1.27 bere a wɔde ahyɛ mu ma no ma ɛba fam sen 1.10 bere a ɛso atew no. Saa dodow a ɛso tew yi ma electrochemical reaction no brɛ ase kosi sɛ acid a ɛnnɔɔso no bɛkɔ so ayɛ nea ɛbɛma ɛlɛtrɔnik akɔ so yiye.
Dwuma a nkwammoaa a ebetumi ayɛ adwuma di .
Electrochemical reactions ba bere a nhyehyɛe no wɔ anyinam ahoɔden a ɛdɔɔso a ɛbɛma electron akɔ so. Nernst equation no kyerɛ saa abusuabɔ yi dodow, ɛkyerɛ sɛnea nkwammoaa tumi gyina reactant dodow, ɔhyew, ne gyinapɛn electrode tumi a ɛwɔ nneɛma a ɛfa ho no so.
Standard electrode potentials na ɛkyerɛ nneyɛe a ɛkɔ so ara kwa. Nneɛma a ɛwɔ gyinapɛn ahorow a enye kɛse no ma electron ahorow no ntɛm, na ɛma ɛyɛ anode a ɛfata. Wɔn a wɔn bo yɛ papa kɛse no gye ɛlɛtrɔnik tom, na ɛyɛ adwuma sɛ cathodes. Nsonsonoe a ɛda saa tumi ahorow yi ntam no de cell no voltage-tumi a ɛkanyan adeyɛ no si hɔ.
Sɛ voltaic nkwammoaa bi fi mu ba a, nkwammoaa no tumi no so tew nkakrankakra bere a reactant dodow sesa no. Nneyɛe no kɔ so kosi sɛ nhyehyɛe no bedu pɛyɛ, na ɛno na tumi a ebetumi aba no so tew kɔ zero na net electron flow biara mma. Ansa na saa equilibrium tebea yi, electrochemical reaction no kɔ so wɔ rate a ɛne mprempren density no hyia.
Overpotential ahwehwɛde ahorow .
Electrochemical reactions ankasa taa hwehwɛ overpotential-additional voltage a ɛboro thermodynamic minimum no so. Saa ahoɔden a ɛboro so yi di activation barriers a ɛma ɛlɛtrɔnik kɔ ne mass transport anohyeto ahorow so nkonim. Overpotential no gu ahorow wɔ reaction type, electrode material, ne current density.
Fast reactions a low overpotential kɔ so yiye wɔ minimal excess voltage. Nneyɛe a ɛyɛ mmerɛw no hwehwɛ sɛ ɛboro so kɛse na ama wɔanya mprempren nsu a ɛsen no. Eyi kyerɛkyerɛ nea enti a electrolytic akwan horow bi hwehwɛ sɛ wonya ahoɔden a ɛkorɔn kɛse sen sɛnea nsusuwii mu akontaabu kyerɛ no mu.
Nnwuma a wɔde di dwuma wɔ nnwuma ahorow nyinaa mu .
Electrochemical reactions tumi mfiri ne akwan a wontumi nkan. Batere titiriw a ɛwɔ kanea a wɔde tow ne nea wɔde di dwuma wɔ akyirikyiri mu no gyina nneɛma a wontumi nsakra a ɛma anyinam ahoɔden ba kosi sɛ nneɛma a ɛma nneɛma yɛ adwuma no bɛtwe no so. Battery a ɛtɔ so mmienu wɔ kar ne ɛlɛtrɔnik mfiri mu de reversible reactions di dwuma, na ɛma kwan ma wɔde charge a wɔsan yɛ no-discharge cycles.
Fuel cell no gyina hɔ ma dwumadie soronko bi a ɛwɔ baabi a electrochemical reactions dannan petrol tẽẽ ma ɛyɛ anyinam ahoɔden a ɛyɛ adwuma yiye. Hydrogen yɛ oxidize wɔ anode no so bere a oxygen so tew wɔ cathode no so, na ɛma nsu nkutoo ba sɛ nea efi mu ba. Nea ɛnte sɛ batere no, petrol nkwammoaa hia pɛtro a ɛkɔ so na ama atumi ayɛ adwuma no.
Ntini a ɛyɛ mmerɛw no yɛ nea wɔmpɛ a ɛba wɔ anyinam ahoɔden mu a ɛba ara kwa bere a dade di nkitaho ne oxygen no ho nhwɛso. Dade a ɛyɛ mmerɛw no nam oxidation reactions so ba wɔ anodic mmeae, a ɛlɛtrɔnik sen kɔ cathodic mmeae a oxygen so tew. Saa electrochemical mechanisms yi ho nteaseɛ boa mfiridwumayɛfoɔ ma wɔyɛ ahobanbɔ coatings ne corrosion-sentifed alloys.
Mfiridwuma mu electrochemistry ma tumi kɛse-scale production nhyehyɛe ahorow. Aluminium a wɔyɛ no gyina aluminum oxide a ayow a wɔde anyinam ahoɔden yɛ so, na wɔde nsu akɛse di dwuma de tew aluminium ions so. Chloralkali no de anyinam ahoɔden yɛ brine ma ɛyɛ chlorine mframa ne sodium hydroxide, a ne nyinaa yɛ mfiridwuma mu nnuru a ɛho hia.
Reaction kinetics ne rate factors .
Electrochemical reaction rates gyina nneɛma pii a ɛka bom so. Mprempren density-Mprempren biara a ɛwɔ unit electrode area-Daaa mu no ne reaction rate no wɔ abusuabɔ sɛnea Faraday mmara kyerɛ no. Mprempren density a ɛkorɔn kyerɛ sɛ ɛlɛtrɔnik pii a ɛkɔ sekan biara mu, na ɛma nnuru no dannan no ntɛmntɛm.
Mass transport to electrochemical reactions pii ano hye. Ɛsɛ sɛ reactants no du electrode no ani, na ɛsɛ sɛ nneɛma a wɔyɛ no kɔ akyiri na ama concentration gradients akɔ so ayɛ adwuma. Diffusion, migration, ne convection na ɛkyerɛ akwantu nhyehyɛe ahorow yi kwan. Electrolyte a wɔkanyan no anaasɛ ɛyɛ flow no ho nhyehyɛe-anam nkwammoaa so ma nneɛma pii kɔ na ɛma nneyɛe a wotumi yɛ no yɛ kɛse.
Electrode no ani fã kɛse no ara ho hia kɛse. Nneɛma akɛse a ɛwɔ soro no ma wonya mmeae pii a wɔde ɛlɛtrɔnik kɔ, na ɛma wotumi yɛ nsu a ɛkɔ soro nyinaa wɔ current density koro no ara mu. Eyi kyerɛkyerɛ nea enti a battery electrodes de porous structures a ɛwɔ sorosoro a ɛwɔ soro-ɛde-volume ratios di dwuma, na ɛma interface no yɛ kɛse wɔ baabi a reactions ba no.
Electrode ade no ankasa nya reaction kinetics so nkɛntɛnso denam catalytic effects so. Nneɛma bi a wɔde yɛ adwuma no ma ahoɔden a wɔde yɛ adwuma no so tew ma nneyɛe pɔtee bi, na ɛma ɛkɔ so ntɛmntɛm wɔ nea ɛboro so a ɛba fam mu. Platinum ma hydrogen oxidation ne oxygen so tew yiye, na ɛma ɛyɛ nea ɛsom bo ma petrol nkwammoaa mu electrode ahorow ɛmfa ho sɛ ɛho ka yɛ den no.
Nneɛma a ɛwɔ soro abien .
Electrode-electrolyte ntam nkitahodi no wɔ nhyehyɛe a ɛyɛ den a wɔfrɛ no anyinam ahoɔden abien. Saa ɔmantam yi concentrates charge wɔ nanometers kakraa bi so, na ɛma anyinam ahoɔden a emu yɛ den a ɛdu 10⁷ V/cm. Double layer no yɛ adwuma te sɛ capacitor, a ɛkora charge a ɛwɔ electrochemical reaction kinetics so nkɛntɛnso.
ions a ɛwɔ solution mu no kyerɛ wɔn ho kwan wɔ baabi a ɛbɛn electrode a ɛwɔ ahoɔden no ani. Cations boaboa ano wɔ negative electrode ahorow ho, bere a anions no yɛ kɛse wɔ electrode ahorow a ɛyɛ papa so. Saa ion nhyehyɛe yi hwehwɛ electrode charge no mu na ɛka mmoa ahorow a wobetumi adu soro ma wɔayɛ wɔn ade no. Nneɛma a ɛwɔ afã abien no nhyehyɛe no sesa wɔ ɔkwan a ɛyɛ nnam so bere a electrode tumi no gu ahorow no, ɛwɔ nkɛntɛnso akwan ne rates so nkɛntɛnso.
Nkɛntɛnso a ɛwɔ afã abien nkɛntɛnso ho ntease da adi sɛ ɛho hia kɛse ma electrochemical nhyehyɛe ahorow a ɛyɛ papa. Nhwehwɛmufo sua saa nanoscale phenomena yi ho ade de yɛ battery electrode a eye, ɛma corrosion resistance tu mpɔn, na wɔyɛ electrocatalysts a etu mpɔn kɛse. Nkyem mmienu no gyina hɔ ma baabi a molecule-level chemistry hyia macroscopic electrical phenomena.
Nsɛm a Wɔtaa Bisa .
Nsonsonoe bɛn na ɛwɔ galvanic ne electrolytic nkwammoaa ntam?
Galvanic nkwammoaa no ma anyinam ahoɔden fi nnuru a ɛba ara kwa mu, te sɛ batere a ɛrebɔ. Electrolytic cells de anyinam ahoɔden a wɔde di dwuma di dwuma de ma non-nneɛma a ɛba bere a ɛba fam, te sɛ batere a wɔde bɔ anyinam ahoɔden anaasɛ anyinam ahoɔden a wɔde yɛ nneɛma. Nsonsonoe titiriw a ɛwɔ mu ne sɛ ebia adeyɛ no ba wɔ abɔde mu (Galvanic) anaasɛ ɛhwehwɛ abɔnten tumi (electrolytic).
So electrochemical reactions betumi aba a nsu mu electrolyte nni mu?
Yiw, ɛwom sɛ ɛnyɛ nea ɛtaa ba de. Solid-State battery de electrolytes a ɛyɛ den a ɛnam wɔn ahwehwɛ nhyehyɛe so di dwuma. High-temperature solid oxide fuel cells de ceramic electrolytes di dwuma. Mframa bi mpo betumi ayɛ electrolytes wɔ tebea pɔtee bi mu. Nanso, nsu mu electrolytes da so ara yɛ nea ɛtaa ba esiane ionic conductivity a ɛkorɔn nti.
Dɛn nti na electrochemical reactions gyina wɔ equilibrium so?
Wɔ equilibrium mu no, anim ne akyi reaction rates kari pɛ pɛpɛɛpɛ. Nsakrae biara a ɛba netɛm mu no mma, enti ɛlɛtrɔnik biara nsen fa ɔmansin no mu. Nkwammoaa tumi no so tew kɔ zero efisɛ nhyehyɛe no duu ne ahoɔden tebea a ɛba fam koraa no mu. Reactants a wode bɛka ho anaasɛ external voltage a wode bedi dwuma no betumi asan afi reaction no ase.
Ɔkwan bɛn so na ɔhyew mu nsakrae ka saa nneyɛe yi?
Mpɛn pii no, ɔhyew a ɛkɔ soro no ma nneyɛe a ɛkɔ soro no kɔ soro denam ion a ɛkɔ ntɛmntɛm ne ahoɔden a wɔde yɛ adwuma no akwanside a ɛba fam no so. Nanso, ɔhyew a ɛboro so betumi asɛe batere no afã horow anaasɛ ɛbɛkanyan runaway reactions. Awɔw mu hyew no brɛ ase kɛse, na ɛma ahoɔden a ɛba no so tew. Electrochemical nhyehyɛe biara wɔ ɔhyew a eye sen biara ma adwumayɛ a ɛsen biara.
Electrochemical reactions bridge chemistry ne electrical engineering wɔ akwan horow so a ɛka yɛn da biara da asetra bere nyinaa. Efi battery a ɛwɔ wo smartphone so kosi anti-corrosion coating so wɔ dade nhyehyɛe so no, saa electron transfer akwan yi wɔ electrode so no ma nnɛyi mfiridwuma tumi yɛ yiye. Nneyɛe no ba bere biara a electrode, electrolyte, ne nnuru a ɛma kar no tumi anaasɛ ahoɔden a wɔde di dwuma no bom a ɛfata no bom-ahoɔden a ɛdannan wɔ nnuru ne anyinam ahoɔden ntam a ɛyɛ adwuma yiye.
Nsɛmti a ɛfa ho ma akenkan foforo:
Nernst equation ne nkwammoaa a ebetumi ayɛ akontaabu .
Battery nnuru ne ahoɔden a wɔkora so .
Nneɛma a ɛma nsu no nsɛe ne ne kwan a wɔfa so siw ano .
Electrocatalysis ne electrode nneɛma .
Nneɛma a wɔde yɛ pɛtro .
