Mohlala oa Lipotso tsa Puisano ea Electrochemistry
Electrochemistry ke lekala la k'hemistri le ithutang kamano pakeng tsa diketso tsa dikhemikhale le diphetoho matleng a motlakase. Ho electrochemistry, ho na le dikgopolo tse pedi tse kgolo: oxidation (tokollo ya dielektrone) le phokotso (phaello ya dielektrone). Ditshebetso tsena di ka bonwa mefuteng e mmedi ya disele tsa electrochemical: disele tsa voltaic (disele tsa galvanic) le disele tsa electrolytic. Ka tlase ke mehlala e meng ya mathata le ditlhaloso tsa ona ho o thusa ho utlwisisa electrochemistry.
Mohlala oa Potso ea 1: Sele ea Voltaic
Potso:
Ha ho fanoe ka sele ea voltaic e nang le li-electrode tsa zinki (Zn) le koporo (Cu) tse hokahantsoeng ka borokho ba letsoai. Zn e qoelisoa ka har'a tharollo ea 1 M ZnSO4 'me Cu e qoelisoa ka har'a tharollo ea 1 M CuSO4. Ngola likarabelo tse hlahang ho electrode ka 'ngoe 'me u bale phapang e ka bang teng (EMF) ea sele ea voltaic. Lintlha tse tloaelehileng tsa bokhoni ba electrode:
\[ E^o_{\text{Zn}^{2+}/\text{Zn}} = -0.76 \, \text{V} \]
\[ E^o_{\ mongolo{Cu}^{2+}/\mongolo{Cu}} = +0.34 \, \mongolo{V} \]
Puisano:
Mohato oa pele ke ho fumana karabelo ea redox e hlahang. Seleng ea voltaic, karabelo ea redox e sa reroang e etsahala moo
– Zinc (Zn) e feta ka oxidation:
\[ \text{Zn (s)} \rightarrow \text{Zn}^{2+} (aq) + 2e^- \]
– Koporo (Cu) e fokotseha:
\[ \mongolo{Cu}^{2+} (aq) + 2e^- \mongolo o ka ho le letona{Cu (s)} \]
Karabelo e felletseng ea redox ka seleng ea voltaic ke:
\[ \text{Zn (s)} + \text{Cu}^{2+} (aq) \rightarrow \text{Zn}^{2+} (aq) + \text{Cu (s)} \]
Ka mor'a moo, re tla bala phapang ea bokhoni ba sele:
\[ E_{\text{cell}} = E^o_{\text{cathode}} – E^o_{\text{anode}} \]
Moo:
– Cathode ke electrode moo phokotso (Cu) e etsahalang teng.
– Anode ke electrode moo ho etsahalang oxidation (Zn).
E le hore,
\[ E_{\text{sel}} = 0.34 \, \text{V} – (-0.76 \, \text{V}) \]
\[ E_{\text{sel}} = 0.34 \, \text{V} + 0.76 \, \text{V} = 1.10 \, \text{V} \]
Qetello:
– Karabelo e hlahang ho anode (Zn):
\[ \text{Zn (s)} \rightarrow \text{Zn}^{2+} (aq) + 2e^- \]
– Karabelo e hlahang ho cathode (Cu):
\[ \mongolo{Cu}^{2+} (aq) + 2e^- \mongolo o ka ho le letona{Cu (s)} \]
– Phapang ea bokhoni ba sele (EMF): 1.10 V
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Mohlala oa Potso ea 2: Sele ea Electrolytic
Potso:
Ha ho etsoa electrolysis ea tharollo ea NaCl, bolela likarabelo tse hlahang ho cathode le anode haeba ho sebelisoa electrode e sa sebetseng, joalo ka platinum (Pt). Bala kakaretso ea tefiso e hlokahalang ho hlahisa gram e le 'ngoe ea Cl2. (Ar Cl = 35.5)
Puisano:
Mohato oa pele ke ho ngola likarabo tse hlahang ho electrode ka 'ngoe ka har'a tharollo ea letsoai la NaCl.
– Ka cathode (phokotso):
Ts'ebetsong ena, li-ion tsa H+ tse tsoang metsing li tla fokotseha:
\[ 2H_2O(l) + 2e^- \ motsu H_2(g) + 2OH^-(aq) \]
– Ho anode (oxidation):
Cl-ion e tla feta oxidation ho fetoha khase ea Cl2:
\[ 2Cl^-(aq) \ motsu Cl_2(g) + 2e^- \]
Karabelo e Felletseng:
Kahoo karabelo e felletseng e hlahang ka har'a electrolysis ea tharollo ea NaCl ke:
\[ 2NaCl(aq) + 2H_2O(l) \ motsu o letona 2NaOH(aq) + H_2(g) + Cl_2(g) \]
Ho bala tefiso e hlokahalang ho hlahisa gram e le 'ngoe ea Cl2, re hloka ho fumana palo ea li-moles tsa Cl2:
\[ \mongolo{Boima ba Cl}_2 = 1 \mongolo{gram} \]
\[ \mongolo{Ar Cl}_2 = 2 \makgetlo a 35.5 = 71 \mongolo{ gram/mol} \]
\[ \text{Palo ea li-moles tsa Cl}_2 = \frac{1}{71} \text{ mol} \]
Ho latela equation ea karabelo ho anode, 1 mol ea Cl2 e hlahisoa ho tsoa ho 2 mol ea lielektrone:
\[ 2Cl^- \motsu o nepahetseng Cl_2 + 2e^- \]
Ka mantsoe a mang, mole e le 'ngoe ea Cl2 e hloka limole tse peli tsa lielektrone.
Palo ea li-mole tsa lielektrone:
\[ \text{Palo ea li-mole tsa lielektrone} = 2 \times \frac{1}{71} = \frac{2}{71} \text{ mol} \]
Tefiso e hlokahalang e ka baloa ho sebelisoa boleng ba Faraday (F = 96485 C/mol e^-):
\[ Q = n \makgetlo F \]
\[ Q = \left(\frac{2}{71} \text{ mol}\right) \times 96485 \text{ C/mol} \]
\[ Q = 2718 \mongolo{ C} \]
Qetello:
– Karabelo ho cathode:
\[ 2H_2O(l) + 2e^- \ motsu H_2(g) + 2OH^-(aq) \]
– Karabelo ho anode:
\[ 2Cl^-(aq) \ motsu Cl_2(g) + 2e^- \]
– Tefiso eohle e hlokahalang ho hlahisa gram e le 1 ea Cl2 ke 2718 C.
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Mohlala oa 3: Kamano ea Nernst le Maemo a sa Tloaelehang
Potso:
Bala bokgoni ba sele ya voltaic e entsweng ka di-electrode tsa Ag/Ag+ tse nang le mahloriso a ioni ya silevera ya di-electrode tsa 0.1 M le Zn/Zn2+ tse nang le mahloriso a 0.01 M. Bokgoni bo tloaelehileng ba di-electrode ke:
\[ E^o_{\text{Ag}^{+}/\text{Ag}} = +0.80 \, \text{V} \]
\[ E^o_{\text{Zn}^{2+}/\text{Zn}} = -0.76 \, \text{V} \]
Puisano:
Mohato oa pele ke ho ngola likarabo tse hlahang:
– Ho ntsha oksijene ho anode (Zn):
\[ \text{Zn (s)} \rightarrow \text{Zn}^{2+} (aq) + 2e^- \]
– Phokotso ho cathode (Ag):
\[ \text{Ag}^{+} (aq) + e^- \rightarrow \text{Ag (s)} \]
Karabelo eohle:
\[ \text{Zn (s)} + 2\text{Ag}^{+} (aq) \rightarrow \text{Zn}^{2+} (aq) + 2\text{Ag (s)} \]
Ho ipapisitsoe le equation ea Nernst:
\[ E_{\text{Cell}} = E^o_{\text{Cell}} – \left( \frac{0.0592}{n} \right) \log \left( \frac{[\text{product}]}{[\text{reactant}]} \right) \]
Moo:
\[n = 2 \]
Taba ea pele, bala E^o_{\text{Sel}}:
\[ E^o_{\text{Sel}} = E^o_{\text{Ag}^{+}/\text{Ag}} – E^o_{\text{Zn}^{2+}/\text{Zn}} \]
\[ E^o_{\text{Sel}} = 0.80 \, \text{V} – (-0.76 \, \text{V}) \]
\[ E^o_{\text{Cell}} = 1.56 \, \text{V} \]
Ka mor'a moo, bala bokhoni ba 'nete ba sele ka mahloriso a fanoeng:
\[ E_{\text{Sel}} = 1.56 \, \text{V} – \left( \frac{0.0592}{2} \right) \log \left( \frac{[\text{Zn}^{2+}]}{[\text{Ag}^{+}]^2} \right) \]
\[ E_{\text{Sel}} = 1.56 \, \text{V} – \left( \frac{0.0592}{2} \right) \log \left( \frac{0.01}{(0.1)^2} \right) \]
\[ E_{\text{Sel}} = 1.56 \, \text{V} – 0.0296 \log \left( \frac{0.01}{0.01} \right) \]
\[ E_{\text{Cell}} = 1.56 \, \text{V} \]
Qetello:
– Likarabelo tse hlahang ho anode le cathode li lula li tšoana
– Bokgoni ba sele bo nang le mahloriso a fanoeng ke 1.56 V
Sengoloa sena se bontša mokhoa oa ho rarolla mefuta e 'maloa ea mathata a electrochemistry, ho kenyeletsoa mathata a amanang le lisele tsa voltaic, lisele tsa electrolytic, le lipalo ho sebelisoa Nernst Equation. Kutloisiso e felletseng ea melao-motheo e ka morao ho liketso tsa redox le bokhoni ba ho sebelisa data ea electrochemical ke tsa bohlokoa bakeng sa katleho ho rarolleng mefuta ena ea mathata.
