Zitsanzo za Mafunso Okhudza Kugwiritsa Ntchito Deta Yovomerezeka ya Electrode
Mphamvu yamagetsi yokhazikika (E°) imagwira ntchito yofunika kwambiri mu chemistry, makamaka pakumvetsetsa machitidwe a redox ndi electrochemical. Imapereka njira yodziwira komwe machitidwe a redox amachitikira ndikuyerekeza mphamvu za okosijeni ndi zochepetsera. Nkhaniyi ipereka zitsanzo zingapo za kugwiritsa ntchito deta yamagetsi yokhazikika kuti iwonetse momwe imagwirira ntchito m'mikhalidwe yeniyeni.
Chiyambi cha Standard Electrode Potentials
Mphamvu ya electrode yokhazikika imayesa momwe chinthu kapena chinthu chimakhalira kuti chipeze kapena kutaya ma elekitironi pansi pa mikhalidwe yokhazikika (1 M, 1 atm, ndi 25°C). Mphamvu ya electrode yokhazikika imafotokozedwa mu volts (V) ndipo nthawi zambiri imayerekezeredwa ndi mphamvu ya hydrogen electrode yokhazikika (SHE), yomwe imatengedwa ngati 0 V.
Chitsanzo Funso 1: Kudziwa Zomwe Zimachitika Mwachibadwa
Funso:
Werengerani ngati zotsatirazi zidzachitika zokha:
\[ \text{Zn}^{2+} + \text{Cu} \rightarrow \text{Zn} + \text{Cu}^{2+} \]
Ma electrode potentials ofunikira ndi awa:
– \(\text{Zn}^{2+} + 2e^{-} \rightarrow \text{Zn} \) \( E° = -0.76 \, \text{V} \)
– \(\text{Cu}^{2+} + 2e^{-} \kachidutswa chakumanja \mawu{Cu} \) \( E° = +0.34 \, \mawu{V} \)
Kukambirana:
1. Tanthauzirani Mayankho a Hafu ya Maselo:
Kuchepetsa theka la maselo:
– Kuchuluka kwa okosijeni: \[\text{Zn}^{2+} + 2e^{-} \rightarrow \text{Zn} \, \text{(Reduction, E° = -0.76 V)} \]
– Kuchepetsa theka la reaction: \[\text{Cu}^{2+} + 2e^{-} \rightarrow \text{Cu} \, \text{(Reduction, E° = +0.34 V)} \]
2. Kuzindikira Kuyankha:
Sinthani zomwe zili ndi mphamvu yotsika kuti zikhale okosijeni:
– \[\text{Zn} \rightarrow \text{Zn}^{2+} + 2e^{-} \, \text{(Oxidation, E° = +0.76 V)} \]
Zotsatira zotsala:
– \[\ malemba{Cu}^{2+} + 2e^{-} \kachidutswa kakumanja \malemba{Cu} \, \malemba{(Kuchepetsa, E° = +0.34 V)} \]
3. Werengani chiwerengero chonse cha E° (mphamvu ya maselo):
– \[ E°_{\text{cell}} = E°_{\text{reduction}} + E°_{\text{oxidation}} = +0.34 \, \text{V} + (+0.76 \, \text{V}) = +1.10 \, \text{V} \]
Popeza mphamvu ya selo (E°_{\text{cell}}) ndi yabwino, izi zimachitika mwadzidzidzi.
Chitsanzo Funso 2: Kudziwa Kuthekera Kofanana
Funso:
Werengerani kuthekera kwa maselo pa zomwe zimachitika pa kutentha koyenera:
\[ \text{Fe}^{2+} + \text{Ag} \rightarrow \text{Fe} + \text{Ag}^{+} \]
Mphamvu yamagetsi yokhazikika:
– \(\text{Fe}^{2+} + 2e^{-} \rightarrow \text{Fe} \) \( E° = -0.44 \, \text{V} \)
– \(\text{Ag}^{+} + e^{-} \rightarrow \text{Ag} \) \( E° = +0.80 \, \text{V} \)
Kukambirana:
1. Tanthauzirani Mayankho a Hafu ya Maselo:
Kuchepetsa theka la maselo:
– \[\text{Fe}^{2+} + 2e^{-} \rightarrow \text{Fe} \, \text{(Reduction, E° = -0.44 V)} \]
– \[\text{Ag}^{+} + e^{-} \rightarrow \text{Ag} \, \text{(Reduction, E° = +0.80 V)} \]
2. Dziwani Mayankho a theka:
Sinthani zomwe zili ndi phindu lochepa loipa (zabwino kwambiri):
– \[\text{Fe} \rightarrow \text{Fe}^{2+} + 2e^{-} \, \text{(Oxidation, E° = +0.44 V)} \]
Zotsatira zotsala:
– \[\text{Ag}^{+} + e^{-} \rightarrow \text{Ag} \, \text{(Reduction, E° = +0.80 V)} \]
3. Werengani chiwerengero chonse cha E° (mphamvu ya maselo):
– \[ E°_{\text{cell}} = E°_{\text{reduction}} + E°_{\text{oxidation}} = +0.80 \, \text{V} + (+0.44 \, \text{V}) = +1.24 \, \text{V} \]
Kuthekera kwa maselo abwino kumasonyeza kuti izi zimachitika zokha pansi pa mikhalidwe yokhazikika.
Chitsanzo 3: Kuwerengera Mphamvu Yopanda Gibbs
Funso:
Dziwani kusintha kwa mphamvu ya Gibbs (ΔG) yaulere pa zomwe zimachitika:
\[ \text{Al} + \text{Cu}^{2+} \rightarrow \text{Al}^{3+} + \text{Cu} \]
Popeza mphamvu ya electrode yokhazikika:
– \(\text{Al}^{3+} + 3e^{-} \rightarrow \text{Al} \) \( E° = -1.66 \, \text{V} \)
– \(\text{Cu}^{2+} + 2e^{-} \kachidutswa chakumanja \mawu{Cu} \) \( E° = +0.34 \, \mawu{V} \)
Kukambirana:
1. Tanthauzirani Mayankho a Hafu ya Maselo:
Kuchepetsa theka la maselo:
– \[\text{Al}^{3+} + 3e^{-} \rightarrow \text{Al} \, \text{(Reduction, E° = -1.66 V)} \]
– \[\ malemba{Cu}^{2+} + 2e^{-} \kachidutswa kakumanja \malemba{Cu} \, \malemba{(Kuchepetsa, E° = +0.34 V)} \]
2. Kuzindikira Kuyankha:
Sinthani zomwe zili ndi mphamvu yotsika kuti zikhale okosijeni:
– \[\text{Al} \rightarrow \text{Al}^{3+} + 3e^{-} \, \text{(Oxidation, E° = +1.66 V)} \]
Zotsatira zotsala:
– \[\ malemba{Cu}^{2+} + 2e^{-} \kachidutswa kakumanja \malemba{Cu} \, \malemba{(Kuchepetsa, E° = +0.34 V)} \]
3. Kusanja kwa Ma Electron:
Yerekezerani chiwerengero cha ma electron pa zomwe zimachitika:
– 2 \(\text{Al} \rightarrow 2\text{Al}^{3+} + 6e^{-} \) \[\text{(Oxidation, E° = +1.66 V)} \]
– 3 \(\mawu{Cu}^{2+} + 6e^{-} \mulole 3\mawu{Cu} \) \[\mawu{(Kuchepetsa, E° = +0.34 V)} \]
4. Werengani chiwerengero chonse cha E° (mphamvu ya maselo):
– \[ E°_{\text{cell}} = (+0.34 \, \text{V} \times 3) + (+1.66 \, \text{V} \times 2) \]
Cholakwika apa: Avereji:
– \[ E°_{\text{cell}} = +0.34 \, \text{V} + +1.66 \, \text{V} = +2.00 \, \text{V}\]
5. Werengerani ΔG:
Fomula: \(\Delta G = -nFE_{\text{cell}}\)
– \[n = 6 \, \malembo{maelekitironi} \]
– \[F = 96485 \, \malemba{C/mol} \]
– \[ \Delta G = -6 \times 96485 \, \text{C/mol} \times +2.00 \, \text{V}\]
- \[ = -1157820 \, \lemba{J/mol} \]
- \[ = -1157.82 \, \ mawu{kJ/mol}\]
Motero, ΔG yoipa imasonyeza kuti izi zimachitika mwadzidzidzi.
Mapeto
Deta yokhazikika ya electrode potential imapereka njira yothandiza yodziwira komwe redox reaction idzapitirire, momwe ingapitirire, komanso ubale wake ndi kusintha kwa mphamvu ya Gibbs free. Chitsanzo cha vutoli pamwambapa chikuwonetsa momwe deta iyi ingagwiritsidwire ntchito kudziwa momwe redox reaction imachitikira komanso kuwerengera mphamvu komwe kumagwirizana nako. Kwa ophunzira kapena aliyense amene amaphunzira chemistry, kumvetsetsa deta yokhazikika ya electrode potential ndi momwe imagwiritsidwira ntchito ndi maziko ofunikira kuti amvetsetse machitidwe ovuta kwambiri a electrochemical.
