Mehlala ea Lipotso tse Buisanang ka Lisele tsa Voltaic
Pendahuluan
Sele ea voltaic, e tsejoang hape e le sele ea galvanic, ke sesebelisoa se fetolang matla a lik'hemik'hale hore e be matla a motlakase ka karabelo ea redox (ho fokotsa oxidation). Sele ea voltaic e na le li-electrode tse peli, tseo hangata li entsoeng ka litšepe tse sa tšoaneng, tse qoelisoang ka har'a electrolyte 'me li hokahantsoe ke borokho ba letsoai. Sehloohong sena, re tla buisana ka mehlala e 'maloa e amanang le lisele tsa voltaic ho tebisa kutloisiso ea rona ea melao-motheo ea tsona ea ts'ebetso le mokhoa oa ho bala bokhoni ba sele.
Khopolo-taba ea Motheo ea Lisele tsa Voltaic
Pele o fetela mathateng a mohlala, ho bohlokoa ho utloisisa likhopolo tsa motheo le likarolo tse etsang sele ea Voltaic:
1. Anode le Cathode: Seleng ea Voltaic, anode ke electrode moo ho etsahalang oxidation, 'me cathode ke electrode moo ho bang le phokotso. Anode e na le tjhaja e mpe, ha cathode e na le tjhaja e ntle.
2. Tsela ea Elektrone: Lielektrone li phalla ho tloha ho anode ho ea ho cathode ka potoloho e kantle, li hlahisa motlakase.
3. Bokgoni ba Sele (Sele ya E): Bokgoni ba sele ke phapang e ka bang teng pakeng tsa di-electrode tse pedi. Bokgoni ba sele bo tlwaelehileng (Sele ya E) bo ka balwa ho sebediswa foromo:
\[
E°sele = E° cathode – E°anode
\]
moo \(E°cathode\) le \(E°anode\) e leng menyetla e tloaelehileng ea phokotso ea cathode le anode.
4. Borokho ba Letswai: Borokho bona bo leka-lekanya litefiso tsa li-ion litharollong tse peli tsa electrolyte ka ho lumella motsamao oa li-ion.
Lipotso tsa Mehlala le Puisano
Ho hlakisa mehopolo ena, ha re buisaneng ka mehlala e meng ea mathata.
Mohlala oa Potso ea 1
Potso:
Bala bokgoni ba sele bo tloaelehileng ba sele ya Volta bo nang le di-electrode tsa Zn | Zn²⁺ (aq) le di-electrode tsa Cu | Cu²⁺ (aq). Ho a tsebahala hore bokgoni ba phokotso bo tlwaelehileng \(E°\) bakeng sa Zn²⁺ | Zn ke -0.76 V le \(E°\) bakeng sa Cu²⁺ | Cu ke +0.34 V.
Puisano:
Mohato oa pele ke ho fumana hore na anode le cathode ke life.
Zn e na le bokgoni ba phokotso e mpe (-0.76 V) ho feta Cu (+0.34 V), kahoo Zn e tla sebetsa e le anode (sebaka sa oxidation) le Cu e le cathode (sebaka sa phokotso).
Ka mor'a moo, re sebelisa foromo:
\[
E°sele = E° cathode – E°anode
\]
Kenya mekhoa e tsebahalang sebakeng sa eona:
\[
Sele ea E = 0.34 V – (-0.76 V)
\]
\[
Sele ea E° = 0.34 V + 0.76 V
\]
\[
Sele ea E° = 1.10 V
\]
Kahoo, bokgoni bo tloaelehileng ba sele ke 1.10 V.
Mohlala oa Potso ea 2
Potso:
Sele ea Voltaic e entsoe ka li-electrode tsa Fe | Fe²⁺ le li-electrode tsa Ag | Ag⁺. Monyetla o tloaelehileng oa phokotso bakeng sa Fe²⁺ | Fe ke -0.44 V le bakeng sa Ag⁺ | Ag ke +0.80 V. Bala bokhoni bo tloaelehileng ba sele 'me u ngole karabelo ea sele.
Puisano:
Jwalo ka pele, re hloka ho fumana anode le cathode. Kaha bokgoni ba phokotso ya Fe²⁺/Fe bo mpe ho feta ba Ag⁺/Ag, Fe e tla sebetsa jwalo ka anode mme Ag e be cathode.
Sebelisa foromo:
\[
E°sele = E° cathode – E°anode
\]
\[
Sele ea E = 0.80 V – (-0.44 V)
\]
\[
Sele ea E° = 0.80 V + 0.44 V
\]
\[
Sele ea E° = 1.24 V
\]
Bokgoni bo tloaelehileng ba sele ke 1.24 V.
Bakeng sa karabelo ea sele ka kakaretso, re kopanya liketso tsa oxidation le tsa phokotso:
– Karabelo ho anode: \( \text{Fe} \rightarrow \text{Fe}^{2+} + 2\text{e}^- \)
– Karabelo ho cathode: \( \text{Ag}^+ + \text{e}^- \rightarrow \text{Ag} \)
Ho leka-lekanya palo ea lielektrone liketsong ka bobeli:
\[
\text{Fe} \rightarrow \text{Fe}^{2+} + 2\text{e}^-
\]
\[
2\mongolo{Ag}^+ + 2\mongolo{e}^- \motsu o nepahetseng 2\mongolo{Ag}
\]
Karabelo e akaretsang ea sele:
\[
\text{Fe} + 2\text{Ag}^+ \rightarrow \text{Fe}^{2+} + 2\text{Ag}
\]
Mohlala oa Potso ea 3
Potso:
Bala bokgoni ba sele ho 25°C bakeng sa sele ya Voltaic e nang le di-electrode tsa Al | Al³⁺ le di-electrode tsa Ni | Ni²⁺, haeba mahloriso a Al³⁺ e le 0.001 M mme mahloriso a Ni²⁺ e le 1 M. Ho a tsebahala hore \(E°\) bakeng sa Al³⁺ | Al ke -1.66 V le \(E°\) bakeng sa Ni²⁺ | Ni ke -0.23 V.
Puisano:
Taba ea pele, fumana anode le cathode:
– Bokgoni ba phokotso ya Al³⁺/Al bo bobe haholo (-1.66 V) ho feta Ni²⁺/Ni (-0.23 V), kahoo Al ke anode mme Ni ke cathode.
Bokgoni bo tloaelehileng ba sele bo balwa ka tsela ena:
\[
E°sele = E° cathode – E°anode
\]
\[
Sele ea E = -0.23 V – (-1.66 V)
\]
\[
Sele ea E° = -0.23 V + 1.66 V
\]
\[
Sele ea E° = 1.43 V
\]
Ka mor'a moo, re sebelisa Nernst Equation ho bala bokhoni ba sele tlas'a maemo a sa tloaelehang:
\[
E_{sele} = Sele ea E° – \left( \frac{RT}{nF} \right) \ln Q
\]
Moo \( Q = \frac{[\text{Al}³⁺]}{[\text{Ni}²⁺]} \), R ke khase e sa fetoheng (8.314 J/mol·K), T ke mocheso ho Kelvin (298 K ho 25°C), F ke Faraday e sa fetoheng (96485 C/mol), mme n ke palo ya dielektrone (6 bakeng sa dikarabelo tse kenyeletsang Al³⁺ le Ni²⁺).
Kenya boleng bo tsejoang sebakeng sa equation:
\[
Q = \frac{0.001}{1} = 0.001
\]
\[
E_{sele} = 1.43 V – \left( \frac{8.314 \times 298}{6 \times 96485} \right) \ln 0.001
\]
\[
E_{sele} = 1.43 V – \left( \frac{2477.172}{578910} \right) \ln 0.001
\]
\[
Sele_{sele} = 1.43 V – (0.00428) \ln 0.001
\]
\[
\ln 0.001 = -6.907
\]
\[
E_{sele} = 1.43 V – (0.00428 \makgetlo -6.907)
\]
\[
Sele_{sele} = 1.43 V + 0.0295
\]
\[
Sele_{sele} = 1.4595 V
\]
Kahoo, bokgoni ba sele boemong bona ke hoo e ka bang 1.46 V.
Qetello
Sele ea voltaic ke khopolo-taba ea motheo k'hemistri ea motlakase e fetolang matla a lik'hemik'hale hore e be matla a motlakase. Sengoloa sena se hlahisitse metheo ea khopolo-taba ea sele ea Voltaic 'me se fane ka mehlala ho thusa ho hlakisa ts'ebetso ea ho bala bokhoni ba sele. Ka kutloisiso ena, babali ba tla utloisisa hamolemo lisele tsa Voltaic le ts'ebeliso ea tsona maemong a fapaneng.
