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Chapter 7 Electrochemistry

Chapter 7 Electrochemistry. Strong electrolyte. Real electrolyte. Weak el ectrolyte. Potential electrolyte. 7.1 Thermodynamic Properties of Electrolyte Solutions. 7.1.1 Electrolyte. NaNO 3 z + ＝ 1 ｜ z - ｜＝ 1 1-1 ； BaSO 4 z + ＝ 2 ｜ z - ｜＝ 2 2-2 ；

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Chapter 7 Electrochemistry

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  1. Chapter 7 Electrochemistry Strong electrolyte Real electrolyte Weak el ectrolyte Potential electrolyte 7.1 Thermodynamic Properties of Electrolyte Solutions 7.1.1 Electrolyte NaNO3z+＝1 ｜z-｜＝1 1-1； BaSO4z+＝2 ｜z-｜＝2 2-2； Na2SO4 z+＝1 ｜z-｜＝2 1-2； Ba(NO3)2 z+＝2 ｜z-｜＝1 2-1。

  2. 7.1.2 Chemical Potential of Electrolyte and Ions B = ++ + 

  3. dT=0, dp=0, dnA=0 B = ++ + 

  4. ideal solution real solution 7.1.3 Activity and Activity Coefficient

  5. 7.1.4 Mean Activity of Ions and Mean Activity Coefficients

  6. 7.1.5 The Debye - Hückel Limiting Law Ionic atmosphere

  7. H2O b<0.01～0.001mol·kg-1 I — Ionic Strength

  8. 7.1.6 Ionic Strength I<0.01mol·kg-1

  9. 7.2 Conductive Properties of Electrolyte Solutions 7.2.1 Conductance G Conductance;unit Simens S，1S=1Ω-1。  Resistivity ; Ω·m.   Conductivity ; S·m-1.  =K(l/A)G K Cell constant

  10. Λm(K2SO4）＝ 0.02485 S·m2·mol-1 Λm( K2SO4）＝ 0.01243 S · m2 · mol-1 7.2.2 Molar Conductance Λm unit S · m2 · mol-1。

  11. 400 300 200 100 HCl 80 H2SO4 m/(Scm2 mol-1) 60 k/(Sm-1) KOH NaOH KCl 40 AgNO3 20 MgSO4 CH3COOH CH3COOH 0 0.5 1.0 1.5 0 5 10 14 c/(moldm-3) m  c   c cB=0 molar conductivity of infinite dilution 7.2.3 Concentration dependence of  andΛm

  12. At equilibrium 7.2.4 Independent Migration of Ion 7.2.5. Electrolytic Equilibrium of Weak Electrolytes

  13. HOAc H+ + OAc- au=ubu/b＝（1-α）u b/b 

  14. + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + Metal Metal 7.3 Electrochemical system

  15. Metal 1 Metal 2 + + + + + + + + + + Contact potential

  16. + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + Liquid-junction potential (diffusion potential)

  17. 7.4 Equilibrium electrochemistry 7.4.1 Reversible cell (1) Electrode reactions and cell reaction are reversible (2) I  0 (equilibrium)

  18. 7.4.2 The Cell Potentials of Reversible Cell

  19. ---Standard Cell Potentials 7.4.3 The Nernst Equation

  20. 7.4.4 Standard Electrode Potential Standard Hydrogen Electrode ---SHE H+ [a(H+) =1 ] | H2 (p=100kPa) | Pt E=0 SHE  electrode in question (reduction)

  21. Table 11-1 25℃时某些电极的标准电极电势 (p＝100kPa)

  22. For example Cl- -(a)｜Cl2｜Pt： Oxidation state + 2e-  Reduction state EMF = E (R,Reduction)- E (L,Reduction)

  23. Temperature coefficient of cell 7.5 Application of EMF Measurements 7.5.1 Determination of thermodynamics quantities ΔrGm,ΔrSm andΔrHm ΔrGm= - zFEMF

  24. 7.5.2 Determination of γ±

  25. -OH HO- Q QH2 7.5.3 Determination of pH Pt｜H2(p )｜solution(pH=x) ｜KCl (a)｜Hg2Cl2｜Hg QQH2 H+｜Q，QH2｜Pt Q［a(Q)］+2H+［a(H+)]+2e-QH2［a(QH2)］ a(Q)≈a(QH2) 25℃，E＝(0.6997-0.05916pH) V

  26. 7.5.4 Determination ofK and Ksp 7.5.5 Determination of reaction direction ΔrGm=-ZFEMF< 0

  27. a c M  c a Ea M Ec M+ + e- M M++e Cathode process υc； anode process υa； 7.6 kinetics of electrochemical system 7.6.1 Rate of electrochemical reaction

  28. v - Rate of electrochemical reaction molm-2s-1 Current density j j=ZFυ j0:exchange current density

  29. { } { }   { c,e} { a} {a} {c} { c} { a ,e}   {e} { } { e} { }   { c,e} { a} {c} {a} { c} { a,e}   {j} {j} polarization curve (a) electrolytic cell (b)chemical electric source 7.6.2 Polarization and Overpotential Overpotential： ηa —anode overpotential ηc—anode overpotential

  30. Ag+ c0 Ag c'  M+ + e- M Diffusion layer (1). Diffusion overpotential (2). Electrochemical overpotential

  31. + — Power supply I anode(+) cathode(-) Pt Pt O2 H2 H2O H2O 7.6.3 Electrolytic cell (-）Pt｜ H2｜OH-（H2O）｜ O2(p) ｜Pt（+）

  32. _ 外电源 + 电阻 I R V 伏特计 A 电流计 Pt  V  Vd KOH KOH Decomposition voltage Theory decomposition voltage Real decomposition voltage Δ (real)=Δ (theory) + (ηa+｜ηc｜) + IR

  33. Negative electrode：Zn + 2NH4Cl  Zn(NH3)2Cl2 + 2H++ 2e- positive electrode ：2MnO2 + 2H+ + 2e- 2MnOOH Cell reaction：Zn + 2MnO2 + 2NH4Cl Zn(NH3)2Cl2 + 2MnOOH 7.7 Power production and corrosion 7.7.1 Dry Cell Zn｜NH4Cl｜MnO2｜C

  34. Negative electrode ：Pb + H2SO4  PbSO4 + 2H+ + 2e- positive electrode : PbO2 + H2SO4 + 2H+ + 2e- PbSO4 + 2H2O Cell reaction：PbO2 + Pb + 2H2SO4 2PbSO4 + 2H2O 11.7.2 Storage Cell Pb｜H2SO4(ρ＝1.28gcm-3)｜PbO2

  35. Negative electrode: 2Zn + 4OH- 2Zn(OH)2 + 4e- positive electrode : Ag2O2 + 2H2O+ 4e- 2Ag+ 4OH- Cell reaction：2Zn+ Ag2O2 + 2H2O 2Ag+ 2Zn(OH)2 11.7.3.Silver-zinc Cell Zn｜KOH(ωB＝0.40)｜Ag2O｜Ag

  36. 7.7.4. Fuel cell M｜H2(g)｜KOH｜O2(g)｜M

  37. Efficiency of Chemical Electric Source

  38. 7.7.5 Electrochemical corrosion

  39. M+ M+ 2H+ 2H+ H2 H2 2e 2e M M2 M1 Anode process： FeFe2＋+2e- Cathode process： (i)2H++2e-H2↑ (ii)O2+4H++4e-2H2O (i) cell reaction：Fe+2H＋Fe2＋+H2 (ii) cell reaction：Fe+(1/2)O2+2H+Fe2++H2O

  40. { c,e} S {)} { a,e} I

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