Mibvunzo yemuenzaniso uye Kukurukurirana kweStandard Electrode Potential
Pendauluan
Simba remagetsi rakajairwa ipfungwa inokosha mu electrochemistry inotsanangura kugona kwe electrode kukwezva ma electron. Pfungwa iyi inoshandiswa mukuverenga masero e electrochemical uye mukuona kuti chii chinoita kuti redox reactions iite. Simba remagetsi rakajairwa (E°) rinoyerwa pasi pemamiriro ezvinhu akajairwa, kureva pakuwanda kwe 1 M, kumanikidzwa kwe 1 atm, uye tembiricha ye 25°C (298 K). Muchinyorwa chino, tichakurukura mienzaniso yakati wandei yematambudziko akajairwa e electrode uye tichakurukura zvakadzama.
Pfungwa Yekutanga yeStandard Electrode Potential
Simba remagetsi rakajairika, rinoratidzwa seE°, rinotsanangura maitiro emhando yemakemikari ekuderedzwa (gamuchira maerekitironi). Kana kukosha kweE° kuri kwakanaka, maitiro emhando yekuderedzwa ari kukura. Kusiyana neizvi, kana kukosha kweE° kuri kwakaipa, maitiro emhando yekuderedzwa ari kukura (kurasikirwa nemaerekitironi).
Tafura yemagetsi inokwana electrode inopa maE° emaitiro akasiyana-siyana e redox, uye aya mavalues anoshandiswa kuverenga ma electrochemical cell potentials.
Muenzaniso Mubvunzo 1
Mubvunzo:
Zvichienderana nezvikamu zviviri zvinotevera zvema "half-reaction" uye simba razvo re "electrode potentials":
– Ag⁺(aq) + e⁻ → Ag(s), E° = +0.80 V
– Cu²⁺(aq) + 2e⁻ → Cu(s), E° = +0.34 V
Sarudza mukana wemasero (E°_cell) we galvanic cell inoumbwa nezvikamu zviviri izvi.
Kukurukurirana:
Kuti tizive kuti masero ane simba rei, tinofanira kuziva anode ne cathode. Mu galvanic cell, iyo ine electrode potential inoshanda se cathode (nzvimbo yekuderedza) uye iyo ine negative inoshanda se anode (nzvimbo ye oxidation).
1. Ziva Anode neCathode:
– Ag⁺ + e⁻ → Ag, E° = +0.80 V (yakanaka kupfuura dzimwe, saka cathode)
– Cu²⁺ + 2e⁻ → Cu, E° = +0.34 V (yakawanda yakaipa, saka anode)
2. Sarudza Maitiro eOxidation uye Kuderedza:
– Cathode (kuderedza): Ag⁺ + e⁻ → Ag, E°_cathode = +0.80 V
– Anode (oxidation): Cu → Cu²⁺ + 2e⁻, E°_anode = -0.34 V (dzosera nzira yemhinduro uye chiratidzo chekugona)
3. Kuverenga E°_sero:
\[
E°_{sero} = E°_{cathode} – E°_{anode}
\]
\[
E°_{sel} = 0.80\, \text{V} – (-0.34\, \text{V})
\]
\[
E°_{sel} = 0.80\, \text{V} + 0.34\, \text{V} = 1.14\, \text{V}
\]
Saka, simba remasero (E°_cell) riri +1.14 V.
Muenzaniso Mubvunzo 2
Mubvunzo:
Zvichienderana nemaitiro ari pazasi pamwe chete nekwaniso yayo ye electrode:
– Fe³⁺(aq) + e⁻ → Fe²⁺(aq), E° = +0.77 V
– Zn²⁺(aq) + 2e⁻ → Zn(s), E° = -0.76 V
Sarudza mukana wekuti sero rivepo (E°_cell) we galvanic cell uchishandisa ma half-reactions ese ari maviri, uye nyora maitiro ese e sero.
Kukurukurirana:
Sezvatakamboita, tinofanira kutanga taziva anode ne cathode.
1. Ziva Anode neCathode:
– Fe³⁺ + e⁻ → Fe²⁺, E° = +0.77 V (yakanaka, saka cathode)
– Zn²⁺ + 2e⁻ → Zn, E° = -0.76 V (yakanyanya kuipa, saka anode)
2. Sarudza Maitiro eOxidation uye Kuderedza:
– Cathode (kuderedza): Fe³⁺ + e⁻ → Fe²⁺, E°_cathode = +0.77 V
– Anode (oxidation): Zn → Zn²⁺ + 2e⁻, E°_anode = -0.76 V (dzosera nzira yemhinduro uye chiratidzo chekugona)
3. Kuenzanisa Maerekitironi:
Mhinduro yese inofanira kuenzana nehuwandu hwemaerekitironi:
\[
2(\text{Fe}^{3+} + e⁻ → \text{Fe}^{2+})
\]
\[
\text{Zn} → \text{Zn}^{2+} + 2e⁻
\]
Saka mhinduro yakazara yemasero ndeiyi:
\[
2\text{Fe}^{3+} + \text{Zn} → 2\text{Fe}^{2+} + \text{Zn}^{2+}
\]
4. Kuverenga E°_sero:
\[
E°_{sero} = E°_{cathode} – E°_{anode}
\]
\[
E°_{sel} = 0.77\, \text{V} – (-0.76\, \text{V})
\]
\[
E°_{sel} = 0.77\, \text{V} + 0.76\, \text{V} = 1.53\, \text{V}
\]
Saka, simba remasero (E°_cell) riri +1.53 V.
Muenzaniso Mubvunzo 3
Mubvunzo:
Ipa mukana wekuti sero riite sei uye uite zvizere sero regalvanic cell uchishandisa zvinotevera:
– MnO₂(s) + 4H⁺(aq) + 2e⁻ → Mn²⁺(aq) + 2H₂O(l), E° = +1.23 V
– Cr³⁺(aq) + e⁻ → Cr²⁺(aq), E° = -0.50 V
Kukurukurirana:
1. Ziva Anode neCathode:
– MnO₂ + 4H⁺ + 2e⁻ → Mn²⁺ + 2H₂O, E° = +1.23 V (yakanaka, saka cathode)
– Cr³⁺ + e⁻ → Cr²⁺, E° = -0.50 V (yakanyanya kuipa, saka anode)
2. Sarudza Maitiro eOxidation uye Kuderedza:
– Cathode (kuderedza): MnO₂ + 4H⁺ + 2e⁻ → Mn²⁺ + 2H₂O, E°_cathode = +1.23 V
– Anode (oxidation): Cr²⁺ → Cr³⁺ + e⁻, E°_anode = +0.50 V (kudzosera shure gwara rekuita uye chiratidzo chekugona)
3. Kuenzanisa Maerekitironi:
Mhinduro yese inofanira kuenzana nehuwandu hwemaerekitironi:
\[
2(\text{Cr}^{3+} + e⁻ → \text{Cr}^{2+})
\]
\[
\text{MnO}_2 + 4\text{H}^+ + 2e⁻ → \text{Mn}^{2+} + 2\text{H}_2\text{O}
\]
Saka mhinduro yakazara yemasero ndeiyi:
\[
\text{MnO}_2 + 4\text{H}^+ + 2\text{Cr}^{3+} → \text{Mn}^{2+} + 2\text{Cr}^{2+} + 2\text{H}_2\text{O}
\]
4. Kuverenga E°_sero:
\[
E°_{sero} = E°_{cathode} – E°_{anode}
\]
\[
E°_{sel} = 1.23\, \text{V} – (-0.50\, \text{V})
\]
\[
E°_{sel} = 1.23\, \text{V} + 0.50\, \text{V} = 1.73\, \text{V}
\]
Saka, simba remasero (E°_cell) riri +1.73 V.
Mhedziso
Kunzwisisa ma electrode potentials akajairwa kwakakosha mu electrochemistry pakusarudza maitiro e redox reaction uye electrochemical cell potentials. Tichishandisa matanho ataurwa pamusoro apa, tinogona kuverenga zviri nyore masero e redox reaction. Ma electrode potentials akajairwa anoshandiswa kuona anode ne cathode mu galvanic cell, pamwe nekuverenga total cell potential, izvo zvinoratidza kushanda zvakanaka uye gwara re redox reaction.
