Imibuzo Eyisibonelo Exoxa Ngokusetshenziswa Kwedatha Engaba Khona Ye-Electrode Ejwayelekile
I-standard electrode potential (E°) idlala indima ebalulekile kumakhemikhali, ikakhulukazi ekuqondeni ukusabela kwe-redox kanye ne-electrochemical. Ihlinzeka ngendlela yokubikezela isiqondiso sokusabela kwe-redox kanye nokuqhathanisa amandla e-oxidizing kanye ne-reducing agents. Lesi sihloko sizokwethula izibonelo eziningana zokusebenzisa idatha ye-standard electrode potential ukubonisa ukusetshenziswa kwayo ezimweni zangempela.
Isingeniso ku-Standard Electrode Potentials
I-standard electrode potential ilinganisa ukuthambekela kwento noma i-compound ukuthola noma ukulahlekelwa ama-electron ngaphansi kwezimo ezijwayelekile (1 M, 1 atm, kanye no-25°C). I-standard electrode potential ivezwa ngama-volts (V) futhi ivame ukuqhathaniswa ne-standard hydrogen electrode potential (SHE), ethathwa njenge-0 V.
Isibonelo Umbuzo 1: Ukunquma Ukusabela Okuzenzekelayo
Umbuzo:
Bala ukuthi ukusabela okulandelayo kuzokwenzeka ngokuzenzakalelayo yini:
\[ \text{Zn}^{2+} + \text{Cu} \rightarrow \text{Zn} + \text{Cu}^{2+} \]
Amandla ajwayelekile e-electrode adingekayo yilawa:
– \(\text{Zn}^{2+} + 2e^{-} \rightarrow \text{Zn} \) \( E° = -0.76 \, \text{V} \)
– \(\umbhalo{Cu}^{2+} + 2e^{-} \umcibisholo \umbhalo{Cu} \) \( E° = +0.34 \, \umbhalo{V} \)
Ingxoxo:
1. Chaza Ukusabela Kwengxenye Yeseli:
Ukunciphisa ukusabela kwesigamu-seli:
– Ukusabela kwesigamu se-oxidation: \[\text{Zn}^{2+} + 2e^{-} \rightarrow \text{Zn} \, \text{(Reduction, E° = -0.76 V)} \]
– Ukunciphisa ukusabela okuyingxenye: \[\text{Cu}^{2+} + 2e^{-} \rightarrow \text{Cu} \, \text{(Reduction, E° = +0.34 V)} \]
2. Ukuhlonza Ukusabela:
Buyisela emuva ukusabela okunamandla aphansi ukuze kube yi-oxidation:
– \[\text{Zn} \rightarrow \text{Zn}^{2+} + 2e^{-} \, \text{(Oxidation, E° = +0.76 V)} \]
Ukusabela okusele:
– \[\umbhalo{Cu}^{2+} + 2e^{-} \umcibisholo \umbhalo{Cu} \, \umbhalo{(Ukunciphisa, E° = +0.34 V)} \]
3. Bala i-E° iyonke (i-Cell potential):
– \[ E°_{\text{cell}} = E°_{\text{reduction}} + E°_{\text{oxidation}} = +0.34 \, \text{V} + (+0.76 \, \text{V}) = +1.10 \, \text{V} \]
Njengoba amandla eseli (E°_{\text{cell}}) elungile, lokhu kusabela kwenzeka ngokuzenzakalelayo.
Isibonelo Umbuzo 2: Ukunquma Amandla Okulingana
Umbuzo:
Bala amandla eseli okusabela okulandelayo ekushiseni okujwayelekile:
\[ \text{Fe}^{2+} + \text{Ag} \rightarrow \text{Fe} + \text{Ag}^{+} \]
Amandla ajwayelekile e-electrode:
– \(\text{Fe}^{2+} + 2e^{-} \rightarrow \text{Fe} \) \( E° = -0.44 \, \text{V} \)
– \(\text{Ag}^{+} + e^{-} \rightarrow \text{Ag} \) \( E° = +0.80 \, \text{V} \)
Ingxoxo:
1. Chaza Ukusabela Kwengxenye Yeseli:
Ukunciphisa ukusabela kwesigamu-seli:
– \[\text{Fe}^{2+} + 2e^{-} \rightarrow \text{Fe} \, \text{(Reduction, E° = -0.44 V)} \]
– \[\text{Ag}^{+} + e^{-} \rightarrow \text{Ag} \, \text{(Reduction, E° = +0.80 V)} \]
2. Thola Ukusabela Okuyingxenye:
Buyisela emuva ukusabela okunenani elincane elibi (elihle kakhulu):
– \[\text{Fe} \rightarrow \text{Fe}^{2+} + 2e^{-} \, \text{(Oxidation, E° = +0.44 V)} \]
Ukusabela okusele:
– \[\text{Ag}^{+} + e^{-} \rightarrow \text{Ag} \, \text{(Reduction, E° = +0.80 V)} \]
3. Bala i-E° iyonke (i-Cell potential):
– \[ E°_{\text{cell}} = E°_{\text{reduction}} + E°_{\text{oxidation}} = +0.80 \, \text{V} + (+0.44 \, \text{V}) = +1.24 \, \text{V} \]
Amandla eseli amahle abonisa ukuthi lokhu kusabela kwenzeka ngokuzenzakalelayo ngaphansi kwezimo ezijwayelekile.
Isibonelo 3: Ukubalwa Kwamandla Amahhala e-Gibbs
Umbuzo:
Nquma ushintsho kumandla amahhala e-Gibbs (ΔG) kumpendulo elandelayo:
\[ \text{Al} + \text{Cu}^{2+} \rightarrow \text{Al}^{3+} + \text{Cu} \]
Uma ubheka amandla ajwayelekile e-electrode:
– \(\text{Al}^{3+} + 3e^{-} \rightarrow \text{Al} \) \( E° = -1.66 \, \text{V} \)
– \(\umbhalo{Cu}^{2+} + 2e^{-} \umcibisholo \umbhalo{Cu} \) \( E° = +0.34 \, \umbhalo{V} \)
Ingxoxo:
1. Chaza Ukusabela Kwengxenye Yeseli:
Ukunciphisa ukusabela kwesigamu-seli:
– \[\text{Al}^{3+} + 3e^{-} \rightarrow \text{Al} \, \text{(Reduction, E° = -1.66 V)} \]
– \[\umbhalo{Cu}^{2+} + 2e^{-} \umcibisholo \umbhalo{Cu} \, \umbhalo{(Ukunciphisa, E° = +0.34 V)} \]
2. Ukuhlonza Ukusabela:
Buyisela emuva ukusabela okunamandla aphansi ukuze kube yi-oxidation:
– \[\text{Al} \rightarrow \text{Al}^{3+} + 3e^{-} \, \text{(Oxidation, E° = +1.66 V)} \]
Ukusabela okusele:
– \[\umbhalo{Cu}^{2+} + 2e^{-} \umcibisholo \umbhalo{Cu} \, \umbhalo{(Ukunciphisa, E° = +0.34 V)} \]
3. Ibhalansi ye-Electron:
Linganisa inani lama-electron okusabela:
– 2 \(\text{Al} \rightarrow 2\text{Al}^{3+} + 6e^{-} \) \[\text{(Oxidation, E° = +1.66 V)} \]
– 3 \(\umbhalo{Cu}^{2+} + 6e^{-} \umcibisholo wangakwesokudla 3\umbhalo{Cu} \) \[\umbhalo{(Ukunciphisa, E° = +0.34 V)} \]
4. Bala i-E° iyonke (i-Cell potential):
– \[ E°_{\text{cell}} = (+0.34 \, \text{V} \times 3) + (+1.66 \, \text{V} \times 2) \]
Iphutha lapha: Isilinganiso:
– \[ E°_{\text{cell}} = +0.34 \, \text{V} + +1.66 \, \text{V} = +2.00 \, \text{V}\]
5. Bala i-ΔG:
Ifomula: \(\Delta G = -nFE_{\text{cell}}\)
– \[n = 6 \, \umbhalo{ama-electron} \]
– \[F = 96485 \, \umbhalo{C/mol} \]
– \[ \Delta G = -6 \times 96485 \, \text{C/mol} \times +2.00 \, \text{V}\]
– \[ = -1157820 \, \umbhalo{J/mol} \]
– \[ = -1157.82 \, \umbhalo{kJ/mol}\]
Ngakho-ke, i-ΔG engemihle ikhombisa ukuthi lokhu kusabela kwenzeka ngokuzenzakalelayo.
Isiphetho
Idatha yamandla kagesi ejwayelekile inikeza indlela ewusizo yokubikezela ukuthi ukusabela kwe-redox kuzoqhubeka ngakuphi, ukuthi kungenzeka kangakanani ukuqhubeka, kanye nobudlelwano bayo noshintsho lwamandla amahhala e-Gibbs. Inkinga eyisibonelo engenhla ibonisa ukuthi le datha ingasetshenziswa kanjani ukunquma ukwenzeka kokusabela kwe-redox kanye nokubalwa kwamandla okuhambisanayo. Kubafundi noma kunoma ubani ofunda ikhemistri, ukuqonda idatha yamandla kagesi ejwayelekile kanye nezinhlelo zayo kuyisisekelo esibalulekile sokuqonda ukusabela kwe-electrochemical okuyinkimbinkimbi kakhulu.
