IB Chemistry on Redox Design and Nernst Equation

Research Questions: • Effect Diff ZnSO4 / CuSO4 on emf /current in Voltaic Cell

Mg2+ Cu2+

Mg Cu

Cu

Cu2+

Zn

Zn2+

Cu2+

Cu AI

AI3+

Zn Cu

Zn2+ Cu2+

0.1 M 0.1 M

-

- -

-

-

- -

-

+

+ +

+

+

+

+

+

0.1 M 1 M

Effect diff metal pairs on emf/current for Voltaic cell

Metal pair

-ve terminal

+ve terminal

E cell/V Current/A

Mg/Cu Mg Cu 2.70 ?

AI/Cu AI Cu 2.00 ?

Zn/Cu Zn Cu 1.10 ?

Fe/Cu Fe Cu 0.80 ?

Sn/Cu Sn Cu 0.48 ?

Research Questions: • Effect Diff metal pairs on emf/current in Voltaic Cell

Procedure/Method • Cut metal into (1cm x 1cm) for Mg, Al, Zn, Fe, Sn and Cu •Prepare 1.0M MgSO4,AI2(SO4)3,FeSO4, SnSO4, CuSO4

• Pipette 5ml 1M CuSO4 into (+) side of well • Insert Cu to CuSO4 and connect to (+) side of voltmeter •Pipette 5ml 1M MgSO4 into (-) side of well. Insert Mg into solution. • Measure emf and current of Mg/Cu cell •Repeat with diff metal pairs

Metal pair Conc ZnSO4

Conc CuSO4

E /V Current/A

Zn/Cu 0.1 0.1 ? ?

Zn/Cu 0.1 1.0 ? ?

Zn/Cu 0.1 10.0 ? ?

Zn/Cu 1.0 0.1 ? ?

Zn/Cu 10.0 0.1 ? ?

Zn/Cu 10.0 1 ? ?

Zn/Cu 10.0 10.0 ? ?

Zn/Cu 1.0 10.0 ? ?

Effect diff ZnSO4/CuSO4 conc on emf/current for Voltaic cell

Procedure/Method • Cut metal into (1cm x 1cm) for Zn and Cu •Prepare 0.1M ZnSO4, CuSO4

• Pipette 5ml CuSO4 into (+) side of well • Insert Cu to CuSO4 and connect to (+) side of voltmeter • Salt bridge by soaking cotton string in saturated NaCI • Pipette 5ml 0.1M ZnSO4 into (-) side of well • Measure emf and current of Zn/Cu cell •Repeat with diff conc ZnSO4 and CuSO4 shown

Zn2+ Cu2+

Zn Cu

Cu

Cu2+

Zn

Zn2+

Cu2+

Cu Zn

Zn2+

Zn Cu

Zn2+ Cu2+

-

-

-

-

-

-

-

- +

+

+

+

+

+

+

+

Effect diff ZnSO4 conc on emf/current for Voltaic cell


Conc CuSO4

E cell/V Current/A

Zn/Cu 10.0 1.0 ? ?

Zn/Cu 1.0 1.0 ? ?

Zn/Cu 0.1 1.0 ? ?

Zn/Cu 0.01 1.0 ? ?

Zn/Cu 0.001 1.0 ? ?

Research Questions: • Effect Diff ZnSO4 conc on emf /current in Voltaic Cell

Procedure/Method • Cut metal into (1cm x 1cm) for Zn and Cu • Pipette 5ml 1M CuSO4 into (+) side of well • Insert Cu to CuSO4 and connect to (+) side of voltmeter • Salt bridge by soaking cotton string in saturated NaCI • Pipette 5ml 10M ZnSO4 into (-) side of well • Measure emf and current of Zn/Cu cell •Repeat with diff conc ZnSO4 shown

10 M 1 M 1 M 1 M

Effect diff CuSO4 conc 0n emf /current for Voltaic cell


Conc CuSO4

E cell/V Current/A

Zn/Cu 1.0 10.0 ? ?

Zn/Cu 1.0 1.0 ? ?

Zn/Cu 1.0 0.1 ? ?

Zn/Cu 1.0 0.01 ? ?

Zn/Cu 1.0 0.001 ? ?

Research Questions: • Effect Diff CuSO4 conc on emf /current in Voltaic Cell

Procedure/Method • Cut metal into (1cm x 1cm) for Zn and Cu • Pipette 5ml 10M CuSO4 into (+) side of well • Insert Cu to CuSO4 and connect to (+) side of voltmeter • Salt bridge by soaking cotton string in saturated NaCI • Pipette 5ml 1M ZnSO4 into (-) side of well • Measure emf and current of Zn/Cu cell •Repeat with diff conc CuSO4 shown

1 M 10 M 1 M 1 M

Effect diff surface area/electrode size on emf/current for Voltaic cell

Zn2+ Cu2+

Procedure/Method • Cut metal into (1cm x 1cm) for Zn and Cu • Pipette 5ml 1M CuSO4 into (+) side of well • Insert Cu to CuSO4 and connect to (+) side of voltmeter • Salt bridge by soaking cotton string in 1% NaCI • Pipette 5ml 1M ZnSO4 into (-) side of well • Measure emf and current of Zn/Cu cell •Repeat with diff NaCI conc (salt bridge) shown.

Effect diff salt bridge conc on emf /current for Voltaic cell

Zn Cu

Cu

Cu2+

Zn

Zn2+

Conc NaCI (salt bridge)

Conc ZnSO4

Conc CuSO4

E /V Current/A

Zn/Cu (1.0%) 1.0 1.0 ? ?

Zn/Cu (2.0%) 1.0 1.0 ? ?

Zn/Cu (3.0%) 1.0 1.0 ? ?

Zn/Cu (4.0%) 1.0 1.0 ? ?

Zn/Cu (5.0%) 1.0 1.0 ? ?

Research Questions: • Effect Diff salt bridge conc on emf /current in Voltaic Cell

Procedure/Method • Cut metal into (1cm x 1cm) for Zn and Cu • Pipette 5ml 1M CuSO4 into (+) side of well • Insert Cu to CuSO4 and connect to (+) side of voltmeter • Salt bridge by soaking cotton string in saturated NaCI • Pipette 5ml 1M ZnSO4 into (-) side of well • Measure emf and current of Zn/Cu cell •Repeat with electrode size/surface area shown

Metal pair

Zn size Cu size E cell/V Current/A

Zn/Cu 1 x 1 1 x 1 ? ?

Zn/Cu 2 x 2 2 x 2 ? ?

Zn/Cu 4 x 4 4 x 4 ? ?

Zn/Cu 8 x 8 8 x 8 ? ?

Zn/Cu 16 x 16 16 x 16 ? ?

Research Questions: • Effect Diff surface area on emf /current in Voltaic Cell

Cu2+

Cu Zn

Zn2+

Zn Cu

Zn2+ Cu2+

1 % 2 %

-

-

-

-

-

-

-

- +

+ +

+

+

+

+

+

Effect diff cation size/diffusion rate (salt bridge) on emf/current for Voltaic cell

Zn2+ Cu2+

Procedure/Method • Cut metal into (1cm x 1cm) for Zn and Cu • Pipette 5ml 1M CuSO4 into (+) side of well • Insert Cu to CuSO4 and connect to (+) side of voltmeter • Salt bridge by soaking cotton string in 1% NaF • Pipette 5ml 1M ZnSO4 into (-) side of well • Measure emf and current of Zn/Cu cell •Repeat with diff anion size (salt bridge) shown.

Effect diff anion size/diffusion rate (salt bridge) on emf /current for Voltaic cell

Zn Cu

Cu

Cu2+

Zn

Zn2+

Research Questions: • Effect Diff anion size on emf /current in Voltaic Cell

Procedure/Method • Cut metal into (1cm x 1cm) for Zn and Cu • Pipette 5ml 1M CuSO4 into (+) side of well • Insert Cu to CuSO4 and connect to (+) side of voltmeter • Salt bridge by soaking cotton string in 1% LiCI • Pipette 5ml 1M ZnSO4 into (-) side of well • Measure emf and current of Zn/Cu cell •Repeat with diff cation size (salt bridge) shown

Research Questions: • Effect Diff cation size on emf/current in Voltaic Cell

Cu2+

Cu Zn

Zn2+

Zn Cu

Zn2+ Cu2+

Cation size (salt bridge)

Conc ZnSO4

Conc CuSO4

E cell/V Current/A

Zn/Cu (LiCI) 1.0 1.0 ? ?

Zn/Cu (NaCI) 1.0 1.0 ? ?

Zn/Cu (KCI) 1.0 1.0 ? ?

LiCI NaCI

Anion size (salt bridge)

Conc ZnSO4

Conc CuSO4

E

cell/V Current/

A

Zn/Cu (NaF) 1.0 1.0 ? ?

Zn/Cu (NaCI) 1.0 1.0 ? ?

Zn/Cu (NaBr) 1.0 1.0 ? ?

Zn/Cu (NaI) 1.0 1.0 ? ?

Zn/Cu (NaNO3) 1.0 1.0 ? ?

Zn/Cu (NaSO4) 1.0 1.0 ? ?

NaCI NaF

-

- -

-

-

-

+

+

+

+

+

+

-

-

+

+

Effect Temp on emf/current for Voltaic cell

Zn2+ Cu2+

Procedure/Method • Cut metal into (1 x 1) for Cu and Cu •Prepare 1M CuSO4, CuSO4

• Pipette 5ml 1M CuSO4 into (+) side of well • Insert Cu to CuSO4 and connect to (+) side of voltmeter • Salt bridge by soaking cotton string in 1% NaCI • Pipette 5ml 1M CuSO4 into (-) side of well • Measure emf and current of Cu/Cu cell •Repeat with diff CuSO4 conc shown.

Effect diff CuSO4 conc on emf/current for Copper Conc cell

Zn Cu

Cu

Cu2+

Cu

Cu2+

Research Questions: • Effect Diff CuSO4 conc on emf /current in Conc Cell

Procedure/Method • Cut metal into (1cm x 1cm) for Zn and Cu •Prepare 1.0M ZnSO4, CuSO4 at 25C

• Pipette 5ml CuSO4 into (+) side of well • Insert Cu to CuSO4 and connect to (+) side of voltmeter •Pipette 5ml ZnSO4 into (-) side of well • Measure emf and current of Zn/Cu cell at 25C •Repeat with diff temp shown

Research Questions: • Effect Temp on emf/current in Voltaic Cell

Cu2+

Cu Zn

Zn2+

Cu Cu

Cu2+ Cu2+

Temp/C Conc ZnSO4

Conc CuSO4

E cell/V Current/A

Zn/Cu (4oC) 1.0 1.0 ? ?

Zn/Cu (25oC) 1.0 1.0 ? ?

Zn/Cu (40oC) 1.0 1.0 ? ?

Zn/Cu (50oC) 1.0 1.0 ? ?

Zn/Cu (60oC) 1.0 1.0 ? ?

25oC 40oC

Metal pair

- ve Conc CuSO4

+ve Conc CuSO4

E /V

Current/A

Cu/Cu 1.0 1.0 ? ?

Cu/Cu 0.5 1.0 ? ?

Cu/Cu 0.25 1.0 ? ?

Cu/Cu 0.125 1.0 ? ?

Cu/Cu 0.0625 1.0 ? ?

1 M 1 M

-

- -

-

-

- -

-

+

+ +

+

+

+

+

+

0.5 M 1 M

1

]1[

]1[

][

][2

2

c

c

Q

M

M

Cu

ZnQ

Zn half cell (-ve) Oxidation

Cu half cell (+ve) Reduction

Zn/Cu Cell

-e -e

Zn/Cu half cells

Std electrode potential as std reduction potential

Find Eθcell (use reduction potential)

Zn + Cu2+ → Zn2+ + Cu Eθ = ?????

Zn 2+ + 2e ↔ Zn Eθ = -0.76V Cu2+ + 2e ↔ Cu Eθ = +0.34V

Zn ↔ Zn2+ + 2e Eθ = +0.76V Cu2+ + 2e ↔ Cu Eθ = +0.34V Zn + Cu2+ → Zn 2+ + Cu Eθ = +1.10V

Oxidized sp ↔ Reduced sp Eθ/V

Li+ + e- ↔ Li -3.04 K+ + e- ↔ K -2.93 Ca2+ + 2e- ↔ Ca -2.87 Na+ + e- ↔ Na -2.71 Mg 2+ + 2e- ↔ Mg -2.37 Al3+ + 3e- ↔ AI -1.66 Mn2+ + 2e- ↔ Mn -1.19 H2O + e- ↔ 1/2H2 + OH- -0.83

Zn2+ + 2e- ↔ Zn - 0.76

Fe2+ + 2e- ↔ Fe -0.45 Ni2+ + 2e- ↔ Ni -0.26 Sn2+ + 2e- ↔ Sn -0.14 Pb2+ + 2e- ↔ Pb -0.13 H+ + e- ↔ 1/2H2 0.00 Cu2+ + e- ↔ Cu+ +0.15 SO4

2- + 4H+ + 2e- ↔ H2SO3 + H2O +0.17

Cu2+ + 2e- ↔ Cu + 0.34 1/2O2 + H2O +2e- ↔ 2OH- +0.40 Cu+ + e- ↔ Cu +0.52 1/2I2 + e- ↔ I- +0.54 Fe3+ + e- ↔ Fe2+ +0.77 Ag+ + e- ↔ Ag +0.80 1/2Br2 + e- ↔ Br- +1.07 1/2O2 + 2H+ +2e- ↔ H2O +1.23 Cr2O7

2-+14H+ +6e- ↔ 2Cr3+ + 7H2O +1.33 1/2CI2 + e- ↔ CI- +1.35 MnO4

- + 8H+ + 5e- ↔ Mn2+ + 4H2O +1.51 1/2F2 + e- ↔ F +2.87

+1.10 V

Cu2+

-

-

-

-

Zn Cu

+

+

+

+

Std condition 1M

QnF

RTEE ln

Zn +Cu2+→Zn2++Cu E = ?

1M 1M

Zn2+

1 M 1 M

Using Nernst Eqn

E0 = Std condition (1M) – 1.10V

R = Gas constant (8.31)

n = # e transfer (2 e)

F = Faraday constant (96 500C mol -1 )

EE

VE

E

E

10.1

010.1

)1ln()965002(

)29831.8(10.1

Std condition 1M



Zn/Cu Cell

-e -e

Zn/Cu half cells



Zn + Cu2+ → Zn2+ + Cu Eθ = ?????





Zn2+ + 2e- ↔ Zn - 0.76


2- + 4H+ + 2e- ↔ H2SO3 + H2O +0.17


2-+14H+ +6e- ↔ 2Cr3+ + 7H2O +1.33 1/2CI2 + e- ↔ CI- +1.35 MnO4

- + 8H+ + 5e- ↔ Mn2+ + 4H2O +1.51 1/2F2 + e- ↔ F +2.87

+1.10 V

Cu2+

-

-

-

-

Zn Cu

+

+

+

+

Std condition 1M

QnF

RTEE ln


1M 0.1M

Zn2+

10

]1.0[

]1[

][

][2

2

c

c

Q

M

M

Cu

ZnQ

0.1 M 1 M

Using Nernst Eqn





VE

E

E

07.1

03.010.1

)10ln()965002(

)29831.8(10.1

Non std 0.1M

E cell decrease ↓ [Cu2+] decrease ↓

↓

Le Chatelier’s principle

↓

Cu2+ + 2e ↔ Cu

↓

[Cu2+] decrease ↓

↓

Shift to left ←

↓

E cell → less ↓ +ve → Cu2+ less able ↓ to receive e- / Cu more able ↑ to lose e-

[Cu2+] ↓ E cell < Eθ

1.07 < 1.10



Zn/Cu Cell

-e -e

Zn/Cu half cells



Zn + Cu2+ → Zn2+ + Cu Eθ = ?????





Zn2+ + 2e- ↔ Zn - 0.76


2- + 4H+ + 2e- ↔ H2SO3 + H2O +0.17


2-+14H+ +6e- ↔ 2Cr3+ + 7H2O +1.33 1/2CI2 + e- ↔ CI- +1.35 MnO4

- + 8H+ + 5e- ↔ Mn2+ + 4H2O +1.51 1/2F2 + e- ↔ F +2.87

+1.10 V

Cu2+

-

-

-

-

Zn Cu

+

+

+

+

Std condition 1M

QnF

RTEE ln


1M 10M

Zn2+

1.0

]10[

]1[

][

][2

2

c

c

Q

M

M

Cu

ZnQ

10 M 1 M

Using Nernst Eqn

E0 =Std condition (1M) – 1.10V




VE

E

E

13.1

03.010.1

)1.0ln()965002(

)29831.8(10.1

Non std 0.1M

E cell increase ↑ [Cu2+] increase ↑

↓


↓

Cu2+ + 2e ↔ Cu

↓

[Cu2+] increase ↑

↓

Shift to right →

↓

E cell → more ↑ +ve → Cu2+ more able receive e-

[Cu2+] ↑ E cell > Eθ

1.13 > 1.10



Zn/Cu Cell

-e -e

Zn/Cu half cells



Zn + Cu2+ → Zn2+ + Cu Eθ = ?????





Zn2+ + 2e- ↔ Zn - 0.76


2- + 4H+ + 2e- ↔ H2SO3 + H2O +0.17


2-+14H+ +6e- ↔ 2Cr3+ + 7H2O +1.33 1/2CI2 + e- ↔ CI- +1.35 MnO4

- + 8H+ + 5e- ↔ Mn2+ + 4H2O +1.51 1/2F2 + e- ↔ F +2.87

+1.10 V

Cu2+

-

-

-

-

Zn Cu

+

+

+

+

Std condition 1M

QnF

RTEE ln


0.1M 1M

Zn2+

1.0

]1[

]1.0[

][

][2

2

c

c

Q

M

M

Cu

ZnQ

1 M 0.1 M

Using Nernst Eqn





VE

E

E

13.1

03.010.1

)1.0ln()965002(

)29831.8(10.1

Non std 0.1M

E cell increase ↑ [Zn2+] decrease ↓

↓


↓

Zn2+ + 2e ↔ Zn

↓

[Zn2+] decrease ↓

↓

Shift to left ←

↓

E cell → more ↑ +ve → Zn more able lose elec

[Zn2+] ↓ E cell > Eθ

1.13 > 1.10



Zn/Cu Cell

-e -e

Zn/Cu half cells



Zn + Cu2+ → Zn2+ + Cu Eθ = ?????





Zn2+ + 2e- ↔ Zn - 0.76


2- + 4H+ + 2e- ↔ H2SO3 + H2O +0.17


2-+14H+ +6e- ↔ 2Cr3+ + 7H2O +1.33 1/2CI2 + e- ↔ CI- +1.35 MnO4

- + 8H+ + 5e- ↔ Mn2+ + 4H2O +1.51 1/2F2 + e- ↔ F +2.87

+1.10 V

Cu2+

-

-

-

-

Zn Cu

+

+

+

+

Std condition 1M

QnF

RTEE ln


10M 1M

Zn2+

10

]1[

]10[

][

][2

2

c

c

Q

M

M

Cu

ZnQ

1 M 10 M

Using Nernst Eqn





VE

E

E

07.1

03.010.1

)10ln()965002(

)29831.8(10.1

Non std 10M

E cell decrease ↓ [Zn2+] increase ↑

↓


↓

Zn2+ + 2e ↔ Zn

↓

[Zn2+] increase ↑

↓

Shift to right →

↓

E cell → less ↓ +ve → Zn less able ↓ lose e-

[Zn2+] ↑ E cell < Eθ

1.07 < 1.10



Zn/Cu Cell

-e -e

Zn/Cu half cells


Zn + Cu2+ → Zn2+ + Cu Eθ = ?





Zn2+ + 2e- ↔ Zn - 0.76


2- + 4H+ + 2e- ↔ H2SO3 + H2O +0.17


2-+14H+ +6e- ↔ 2Cr3+ + 7H2O +1.33 1/2CI2 + e- ↔ CI- +1.35 MnO4

- + 8H+ + 5e- ↔ Mn2+ + 4H2O +1.51 1/2F2 + e- ↔ F +2.87

+1.10 V

Cu2+

-

-

-

-

Zn Cu

+

+

+

+

Std condition 1M

QnF

RTEE ln


0.1M 10M

Zn2+

01.0

]10[

]1.0[

][

][2

2

c

c

Q

M

M

Cu

ZnQ

10 M 0.1 M

Using Nernst Eqn





VE

E

E

16.1

059.010.1

)01.0ln()965002(

)29831.8(10.1

Non std 0.1/10M

E cell increase ↑ [Zn2+] decrease ↓

↓


↓

Zn2+ + 2e ↔ Zn

↓

[Zn2+] decrease ↓

↓

Shift to left ←

↓

E → ↑ +ve → Zn more able lose e-

E cell increase ↑ [Cu2+] increase ↑

↓


↓

Cu2+ + 2e ↔ Cu

↓

[Cu2+] increase ↑

↓

Shift to right →

↓

E→↑ +ve → Cu2+ more able gain e-

+

[Zn2+] ↓/ [Cu2+] ↑E cell > Eθ

Very +ve 1.16 > 1.10

Eθ value DO NOT depend surface area of metal electrode. E cell = Energy per unit charge. (Joule)/C E cell- 10v = 10J energy released by 1C of charge flowing = 100J energy released by 10C of charge flowing Eθ – intensive property– independent of amt – Ratio energy/charge

Increasing surface area metal will NOT increase E cell

Eθ Zn/Cu = 1.10V

Surface area exposed 10 cm2 Total charges 100C leave electrode E cell = 1.1V = 1.1 J energy for 1 C (charges leaving) 1C release 1.1 J energy 100 C release 110 J energy Voltmeter measure energy for 1C – 110J/100C – 1.1V E cell no change

Current – measured in Amperes or Coulombs per second 1A = 1 Coulomb charge pass through a point in 1 second = 1C/s 1 Coulomb charge (electron) = 6.28 x 10 18 electrons passing in 1 second 1 electron/proton carry charge of – 1.6 x 10 -19 C ( very small) 6.28 x 10 18 electron carry charge of - 1 C

ond

electron

ond

CoulombA

sec.1

.1028.6

sec1

11

18

Surface area increase ↑

Total Energy increase ↑

Total Charge increase ↑ Current increase ↑

BUT E cell remain SAME E cell = (Energy/charge) t

QI

tIQ

Q up ↑ – I up ↑

100C flow

110J released

VEcell

Ecell

eCh

EnergyEcell

10.1

100

110

arg

Surface area exposed 10 cm2

Surface area exposed 100cm2

Surface area exposed 100 cm2 Total charges 1000C leave electrode E cell = 1.1V = 1.1 J energy for 1 C (charges leaving) 1 C release 1.1J energy 1000 C release 1100 J energy Voltmeter measure energy for 1C – 1100J/1000C – 1.1V E cell no change

VEcell

Ecell

eCh

EnergyEcell

10.1

1000

1100

arg

Eθ Zn/Cu = 1.10V

1000C flow

1100J released

t

QI

t

QI

Eθ value DO NOT depend surface area of metal electrode. E cell = Energy per unit charge. (Joule)/C E cell- 10v = 10J energy released by 1C of charge flowing = 100J energy released by 10C of charge flowing Eθ – intensive property– independent of amt – Ratio energy/charge


Eθ Zn/Cu = 1.10V

Surface area exposed 10 cm2 Total charges 100C leave electrode E cell = 1.1V = 1.1 J energy for 1 C (charges leaving) 1C release 1.1J energy 100 C release 110 J energy Voltmeter measure energy for 1C – 110J/100C – 1.1V E cell no change





QI

tIQ


100C flow

110J released

VEcell

Ecell

eCh

EnergyEcell

10.1

100

110

arg

Surface area exposed 10 cm2

Surface area exposed 100cm2

Surface area exposed 100 cm2 Total charges 1000C leave electrode E cell = 1.1V = 1.1 J energy for 1 C (charges leaving) 1 C release 1.1J energy 1000 C release 1100 J energy Voltmeter measure energy for 1C – 1100J/1000C – 1.1V E cell no change

VEcell

Ecell

eCh

EnergyEcell

10.1

1000

1100

arg

Eθ Zn/Cu = 1.10V

1000C flow

1100J released

t

QI

t

QI

QnF

RTEE ln

Salt bridge conc

Conc of ion

E cell depend

Nature of electrode Type of metal used Temp of sol

T = Temp in K

Q = Rxn Quotient

E0 = std (1M)

n = # e transfer

F = Faraday constant

(96 500C mol -1 )

R = Gas constant

(8.31)

Eθ Q T

E cell depend

Surface area of contact

Size of cation/anion

Eθ value DO NOT depend surface area of metal electrode. E cell = Energy per unit charge. (Joule)/C E cell- 10v = 10J energy released by 1C of charge flowing = 100J energy released by 10C of charge flowing Eθ – intensive property–independent of amt – Ratio energy/charge






QI

tIQ


QnF

RTEE ln

Salt bridge conc

Conc of ion

E cell depend

Nature of electrode Type of metal used Temp of sol

T = Temp in K

Q = Rxn Quotient

E0 = std (1M)

n = # e transfer F = Faraday constant

(96 500C mol -1 )

R = Gas constant

(8.31)

Eθ Q T

E cell depend

Salt bridge conc



Current/I depend

Eθ cell = EMF in V (std condition) Eθ = Show ease/tendency of species to accept/lose electron Eθ = +ve std electrode potential (strong oxidizing agent – weak reducing agent – accept e-) Eθ = - ve std electrode potential (strong reducing agent - weak oxidizing agent – lose e-) Eθ = written as std reduction potential Eθ DO NOT depend on stoichiometric coefficient. EMF = Energy per unit charge. (Joule)/C EMF 10v = 10J energy released by 1C charge = 100J energy released by 10C charge = 1000J energy released by 100C charge Eθ = Intensive property – INDEPENDENT of amt (Ratio energy/charge) Eθ = +ve suggest rxn feasible, does not tell rate (feasible but may be slow, give no indication rate) Eθ = +ve = Energetically feasible but kinetically non feasible



Resistance high ↑ – current low ↓

EMF = 10V

IB Chemistry on Redox Design and Nernst Equation

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Transcript of IB Chemistry on Redox Design and Nernst Equation