第十三章 伏安和极谱法 Voltammetry and Polarography - PowerPoint PPT Presentation

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第十三章 伏安和极谱法 Voltammetry and Polarography. 什么是伏安和极谱分析法 伏安和极谱分析法是根据测量特殊形式电解过程中的电流 ― 电位(电势)或电流 ― 时间曲线来进行分析的方法。是电分析化学的一个重要分支。. 在含义上,伏安法和极谱法是相同的,而两者的不同在于工作电极: ―― 伏安法的工作电极是电解过程中表面不能更新的固定液态或固态电极 ,如悬汞、汞膜、玻璃碳、铂电极等; ―― 极谱法的工作电极是表面能周期性更新的液态电极 ,即滴汞电极。(有的书把两者统称为极谱法).

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第十三章 伏安和极谱法 Voltammetry and Polarography

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Voltammetry and polarography

Voltammetry and Polarography


Voltammetry and polarography


Voltammetry and polarography


Voltammetry and polarography

1922Heyrovsky 1925


Voltammetry and polarography

1959 20


Voltammetry and polarography


Voltammetry and polarography

102105molL1109 molL1

%


Voltammetry and polarography


Voltammetry and polarography

1.

(1)(Diffusion)

,.,.,


2 convection

2.(convection)

,.,.:a.b..

3.(migrition)

,,.


Voltammetry and polarography


Voltammetry and polarography


Voltammetry and polarography


Voltammetry and polarography


Voltammetry and polarography


Voltammetry and polarography


Voltammetry and polarography


Voltammetry and polarography

,


Voltammetry and polarography

c

c

x

x


Voltammetry and polarography

i

x I

i =xciExuOici-Di(dci/dx)


D dc dx vxc exu 0 c

=++=-D(dC/dX)VxCExU0C

-,(mol/cm2); D-(cm2/s);

Vx-(cm/s); Ex-x(/cm)

C-(mol/L); U0-(cm2/s.v)


Voltammetry and polarography

O+e- =R

j

j=nFi=nFxcinFExuOici-nFDi(dci/dx)


Voltammetry and polarography

KCl

ji=-n F D i(dci/dx)


Voltammetry and polarography

Cix


Voltammetry and polarography

i=A j =A nFDi (coi-csi)/

Coicsi A


Voltammetry and polarography

csi

i= AnFDicoi/=K coi


Voltammetry and polarography

i--t


Voltammetry and polarography


Voltammetry and polarography

=(Dt)1/2

i=(nF AD1/2i coi)/( 1/2t1/2)


Voltammetry and polarography

  • t t33


Voltammetry and polarography


Voltammetry and polarography

1.

i=k (coi-csi)/


Voltammetry and polarography

i=k (coi-csi)/

E3O


Voltammetry and polarography

E0E3Sid

E 1/2


Voltammetry and polarography

2.


Voltammetry and polarography

i=k (coi-csi)/


Voltammetry and polarography

1.


Voltammetry and polarography


Voltammetry and polarography

  • SCE


Voltammetry and polarography

  • DME0.05mm35/


Voltammetry and polarography

  • 0.51mm

    V= EEw+iR

    V=Ew(SCE)


Voltammetry and polarography

  • DME

  • 1.32


Voltammetry and polarography

  • DME

  • DME>0.4V(VS SCE)


Voltammetry and polarography


Voltammetry and polarography

110-3 molL1Cd2+ (0.1 molL1KNO3)


Voltammetry and polarography

2.


Voltammetry and polarography

  • i=ic+if

    Cd2+Cd2+


Voltammetry and polarography

  • BDCd2+Cd2+ : Cd2++2e+Hg==Cd(Hg)

    : 2Hg-2e+2Cl-==Hg2Cl2


Voltammetry and polarography

Cd2+Cd2+SCd2+0(co-cs)/Cd2+Cd2+i ( )


Voltammetry and polarography

  • DE ECd2+DMECd2+DMECd2+Cd2+Cd2+


Voltammetry and polarography

CSi=KsC0


Voltammetry and polarography

E 1/2 DME


Voltammetry and polarography

  • iE


Voltammetry and polarography

  • CS

  • CS


Voltammetry and polarography


Voltammetry and polarography


Voltammetry and polarography

--------

it =708nDqm2/3 t 1/6c

id

id =607nDqm2/3 t 1/6c

=6/7i


Voltammetry and polarography

  • idn

-----

K=607nDqm2/3 t 1/6


Voltammetry and polarography

h1cmid2%

  • qm2/3 t 1/6---

  • id h 1/2


Voltammetry and polarography

I=607nD---InDI


Voltammetry and polarography

  • nDid1.3%/,id1% 0.5


Voltammetry and polarography

  • Dqmt


Voltammetry and polarography


Voltammetry and polarography


Voltammetry and polarography

  • --O2 ,Cu2+,Fe3+


Voltammetry and polarography


Voltammetry and polarography


Voltammetry and polarography


Voltammetry and polarography

(1).

Faraday

if = id + im

Idim


Voltammetry and polarography

250100


Voltammetry and polarography


Voltammetry and polarography


Voltammetry and polarography


Voltammetry and polarography

4.8


Voltammetry and polarography

0.02%0.002%X--100


Voltammetry and polarography


Voltammetry and polarography

-- O28mgL-1,O2


Voltammetry and polarography

  • O2--N2H2CO2H2CO2

  • Na2CO3O2

  • O2--Na2SO3,O2SO32-O2


Voltammetry and polarography

  • --H+

  • -- E 1/2

  • --<0.2V


Voltammetry and polarography

""


Voltammetry and polarography

1

--

--.9,


Voltammetry and polarography

--ssxCx


Voltammetry and polarography

--

  • -- x(x)xsCxx+s


Voltammetry and polarography

x(Cx)Vs(Cs),Hx,Hx+s,


Voltammetry and polarography

  • --x(Cx),s(Cs)Hx+s,Hx+sVs ,Hx+sVs4.10 Vs


Voltammetry and polarography


Voltammetry and polarography


Voltammetry and polarography

()

  • Nernst


Voltammetry and polarography

  • Nernst


Voltammetry and polarography

,


Voltammetry and polarography

(2)


Voltammetry and polarography


Voltammetry and polarography

E 1/2 E 1/2 E 1/2 E 1/2


Voltammetry and polarography

(3)


Voltammetry and polarography


Voltammetry and polarography


Voltammetry and polarography

  • +


Voltammetry and polarography

(1)


Voltammetry and polarography

E 1/2E 1/2


Voltammetry and polarography

Elg id-i/i0.059/nE 1/20.059/n


Voltammetry and polarography

2


Voltammetry and polarography


Voltammetry and polarography

E 1/2


Voltammetry and polarography

---CxE,E --lgCX,

  • n

  • n


Voltammetry and polarography

(E 1/2)c(E 1/2)sK


Voltammetry and polarography

npCxE1/2K

KCx


Voltammetry and polarography

3

1.

2.

3.H+ E 1/2


Voltammetry and polarography

4.

5.


Voltammetry and polarography

1 i--E

  • --


Voltammetry and polarography

  • 5mV/si--E


Voltammetry and polarography

  • 250mV/Si--E


Voltammetry and polarography

  • --767


Voltammetry and polarography

  • --Pt

  • -- i-E


Voltammetry and polarography


Voltammetry and polarography

  • 1.

    ----JP--27S;

    ----


Voltammetry and polarography

5S2S2S--


Voltammetry and polarography

  • 2.E=E0-kt ( E) 0.5Vtk


Voltammetry and polarography

i--tiRE-t


Voltammetry and polarography

  • 3. EDMEi


Voltammetry and polarography


Voltammetry and polarography


Voltammetry and polarography


Voltammetry and polarography


Voltammetry and polarography

  • 4.14


Voltammetry and polarography

3.


Voltammetry and polarography

VV/s Acm2


Voltammetry and polarography

  • Ep

    Ep=E -1.1RT / nF

    = E -0.028 V/n

    56/ n mV,


Voltammetry and polarography

4.

14080

20.0020.25


Voltammetry and polarography

3

4


Voltammetry and polarography

5.

1)

l10-5mol/L 1X10-7mol/L


Voltammetry and polarography

,3.57V0.25ip/id=3.3n1/2ipid


Voltammetry and polarography

2)

20050


Voltammetry and polarography

3

5-10


Voltammetry and polarography

1001000JP5000


Voltammetry and polarography

4

257


Voltammetry and polarography

di/dEdi/dtEd2i/dE2d2i/dt2E16-6


Voltammetry and polarography

9.


Voltammetry and polarography

10.


Voltammetry and polarography

11.

K1K2


Voltammetry and polarography

i-E ipEp ip Ep


Voltammetry and polarography

1

  • 4.15


Voltammetry and polarography

2


Voltammetry and polarography

  • 4.16


Voltammetry and polarography


Voltammetry and polarography

4.


Voltammetry and polarography

ipa=ipc

  • Epa=E +1.1RT / nF


Voltammetry and polarography


Voltammetry and polarography

----Epa Epc


Voltammetry and polarography

Epa=E +1.1RT / nF

Epc=E -1.1RT / nF

Ep= Epa- Epc

=2.2RT / nF

=56.5/n (mV)


Voltammetry and polarography

EpEp55/nmV65/nmV


Voltammetry and polarography


Voltammetry and polarography

Ep59/n mV

ipc/ipa11 4.17B


Voltammetry and polarography

v Epc Epv4.17 C


Voltammetry and polarography

5


Voltammetry and polarography


Voltammetry and polarography

1

23


Voltammetry and polarography

2


Voltammetry and polarography

3


Voltammetry and polarography

  • 4 15


Voltammetry and polarography

  • 225250Hz50mv4.19


Voltammetry and polarography

  • 10-7-10-8 mol/L 4.20


Voltammetry and polarography

  • icif t-1/2 icic


Voltammetry and polarography

  • ic


Voltammetry and polarography

  • 1960Barker2ms


Voltammetry and polarography

icif


Voltammetry and polarography

if20ms ic if


Voltammetry and polarography

NPPDPP

  • --0V4060ms


Voltammetry and polarography

20ms if 4.21


Voltammetry and polarography

ilid67 E1/2


Voltammetry and polarography

  • E5100 mv4080ms4.22(a)


Voltammetry and polarography

20ms20ms4.22(b)i4.22(c)


Voltammetry and polarography

i E1/2i


Voltammetry and polarography

E 1/2,

E


Voltammetry and polarography

Ep= E 1/2E/2

+"-"


Voltammetry and polarography

ift-1/2

iCe-t


Voltammetry and polarography

  • 108 mol/L106107 mol/L 10101011 mol/L

  • 25mV5000


Voltammetry and polarography


Voltammetry and polarography

Stripping Voltammetry

stripping voltammetry4.24D


Voltammetry and polarography

4.24


Voltammetry and polarography

0.8V Cu 2+, Pb 2+ , Cd 2+


Voltammetry and polarography

4.25


Voltammetry and polarography

1071011 mol/L


Voltammetry and polarography


Voltammetry and polarography

(1)


Voltammetry and polarography

(2) 0.1mm0.1mm1.01.5mm


Voltammetry and polarography


Voltammetry and polarography

(3)


Voltammetry and polarography

(4)


Voltammetry and polarography


Voltammetry and polarography


Voltammetry and polarography

ip= -Kc----

ip= KnA/V


Voltammetry and polarography

315min


Voltammetry and polarography


Voltammetry and polarography

l

A === B C

B + ne C E

2

A ne B E

BC==A C

3

A ne B E

B === C C

CEECREC


Voltammetry and polarography

106108 mol/L109 mol/L 1010 mol/L


Voltammetry and polarography

.


Voltammetry and polarography


Voltammetry and polarography


Voltammetry and polarography


Voltammetry and polarography


Voltammetry and polarography


Voltammetry and polarography


Voltammetry and polarography

kk 45%/


Voltammetry and polarography

0.1 mol/L1.2


Voltammetry and polarography

5108 mol/L 104 mol/L


Voltammetry and polarography

11010 mol/L


Voltammetry and polarography

OrgH


Voltammetry and polarography


Voltammetry and polarography

OrgHOrgBHOrg


Voltammetry and polarography

OrgHBHOrgH


Voltammetry and polarography

II4-23


Voltammetry and polarography


Voltammetry and polarography


Voltammetry and polarography


Voltammetry and polarography

1

2

3


Voltammetry and polarography

CdI4 2- Cd 2+


Voltammetry and polarography

108mol/L


Voltammetry and polarography

0.1


Voltammetry and polarography

58


Voltammetry and polarography

107109 mol/L


Voltammetry and polarography


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