Chitsanzo cha Mafunso Okambirana pa Standard Reference Electrode Potential
Pendauluan
Electrochemistry ndi nthambi ya chemistry yomwe imaphunzira ubale womwe ulipo pakati pa zochita za mankhwala ndi zochitika zamagetsi. Limodzi mwa mfundo zazikulu mu electrochemistry ndi electrode potential. Electrode potential ndi muyeso wa momwe electrode imakokera kapena kutulutsa ma elekitironi.
Mu electrochemistry, muyezo womwe umagwiritsidwa ntchito kwambiri ndi standard hydrogen electrode (SHE). SHE imatanthauzidwa kuti ili ndi mphamvu ya zero volts pa kutentha konse. Imagwira ntchito ngati chizindikiro chapadziko lonse choyezera ndikuyerekeza mphamvu za ma electrode ena. Nkhaniyi ikufuna kupereka kufotokozera mwatsatanetsatane kudzera mu zitsanzo za mavuto omwe akukambirana za mphamvu ya standard reference electrode kuti apititse patsogolo kumvetsetsa kwakuya.
Electrode Potential ndi SHE
SHE imagwira ntchito ngati malo ofotokozera ndi mphamvu ya electrode yomwe imayikidwa mwachisawawa pa 0 V. Equation ya reaction ya hydrogen electrode ndi iyi:
\[ 2H^+ (aq) + 2e^- \muvi wa kumanja H_2 (g) \]
M'machitidwe, kutsanzira mikhalidwe ya SHE n'kovuta kupanga ndipo nthawi zambiri kumagwiritsa ntchito ma electrode ena ofunikira monga Saturated Calomel Electrode (SCE) kapena Silver/Silver Chloride (Ag/AgCl).
Mafunso ndi Zokambirana za Zitsanzo
Funso 1: Kudziwa Mphamvu ya Electrode ya Selo ya Electrochemical
Funso:
Mwachitsanzo, tikufunsidwa kuti tidziwe mphamvu ya selo pakati pa Zn(s) ndi Cu^2+(aq). Zimadziwika kuti mphamvu ya electrode yokhazikika ya Zn^2+/Zn ndi -0.76 V ndipo ya Cu^2+/Cu ndi +0.34 V. Kodi mphamvu ya selo ndi yotani pogwiritsa ntchito SHE ngati reference?
Yankho:
Tifunika kuwerengera mphamvu ya selo \( E_{cell} \) pogwiritsa ntchito mphamvu ya electrode. Chiwonkhetso chonse mu selo ndi:
\[ Zn(s) + Cu^{2+}(aq) \rightarrow Zn^{2+}(aq) + Cu(s) \]
Mphamvu ya electrode imalembedwa motere:
\[ E_{selo} = E_{cathode} - E_{anode} \]
Kumene cathode ndi reduction reaction ndipo anode ndi oxidation reaction. Kutengera ndi standard potential:
- Cathode muyezo kuthekera \( E^0_{cathode} \) (Cu^2+/Cu) = +0.34 V
– Mphamvu yokhazikika ya anode \( E^0_{anode} \) (Zn^2+/Zn) = -0.76 V
Kuyika mfundo m'malo:
\[ E_{sel} = 0.34 \, \text{V} – (-0.76 \, \text{V}) \]
\[ E_{sel} = 0.34 \, \malemba{V} + 0.76 \, \malemba{V} \]
\[ E_{cell} = 1.10 \, \text{V} \]
Chifukwa chake, mphamvu ya selo ndi 1.10 V.
Funso 2: Kugwiritsa Ntchito Nernst Equation mu Non-Standard Conditions
Funso:
Werengerani mphamvu ya maselo (E) pa 298 K kuti mupeze momwe ma electrochemical amachitira pakati pa Zn(s) ndi Cu^2+(aq) ngati kuchuluka kwa ma Cu^2+ ions ndi 0.01 M ndipo kuchuluka kwa ma Zn^2+ ions ndi 1.00 M.
Yankho:
Chiyerekezo cha Nernst chimatipatsa njira yowerengera mphamvu ya selo pamene zinthu sizili muyezo (zosakhala muyezo). Chiyerekezo cha Nernst ndi:
\[ E = E^0 – \frac{RT}{nF} \ln Q \]
Kumene,
– \( E^0 \) ndiye mphamvu ya selo yokhazikika
– \( R \) ndiye chokhazikika cha mpweya (8.314 J/mol·K)
– \( T \) ndi kutentha kwa Kelvin (298 K)
– \( n \) ndi chiwerengero cha mamolekyu a ma elekitironi omwe amasamutsidwa mu reaction yofanana (mamolekyu awiri a ma elekitironi a Zn/Cu)
– \( F \) ndi nthawi yosasinthika ya Faraday (96485 C/mol)
– \( Q \) ndi chiwerengero cha mayankho:
\[ Q = \frac{[zogulitsa]}{[zochita]} = \frac{[Zn^{2+}]}{[Cu^{2+}]} \]
Sinthani mfundozo mu equation ya Nernst:
Mphamvu yokhazikika \( E^0 \) kuchokera ku vuto lapitalo ndi 1.10 V.
\[ E = 1.10 \, \text{V} – \frac{8.314 \, \text{J/mol·K} \times 298 \, \text{K}}{2 \times 96485 \, \text{C/mol}} \ln \left(\frac{1.00}{0.01}\right) \]
Choyamba, werengani nthawi ya kutentha ndi chiwerengero cha reaction:
\[ \frac{8.314 \times 298}{2 \times 96485} = \frac{2476.652}{192970} \pafupifupi 0.0128 \, \text{V} \]
Musaiwale kusintha kuti igwirizane ndi J kukhala Volts:
\[ \ln (100) = 4.605 \]
Kotero:
\[ E = 1.10 \, \malemba{V} – 0.0128 \nthawi 4.605 \]
\[ E = 1.10 \, \ zolemba{V} - 0.0589584 \]
\[ E = 1.041 \, \malemba{V} \]
Chifukwa chake, mphamvu ya selo pansi pa mikhalidwe yosakhala yachizolowezi ndi 1.041 V.
Mapeto
Electrochemistry ndi gawo lofunika kwambiri lomwe lili ndi ntchito zambiri mu kafukufuku wamakampani ndi sayansi. Kumvetsetsa mfundo zoyambira monga electrode potential ndi kugwiritsa ntchito Nernst equation kumatithandiza kuwerengera ma cell potentials pansi pa mikhalidwe yosiyanasiyana. Mu chitsanzo ichi, tawona momwe tingadziwire ma cell potential pogwiritsa ntchito standard reference electrode komanso momwe zinthu monga kuchuluka kwa ma cell zimakhudzira ma cell potential.
Kukambiranaku kukuwonetsa kufunika komvetsetsa bwino mfundo zamagetsi pa ntchito zosiyanasiyana, kuyambira ma biosensor mpaka mabatire. Kumaperekanso maziko olimba kwa aliyense amene akufuna kufufuza ndi kugwiritsa ntchito ukadaulo wamagetsi.
