3.2. Chương 4. Sự Vận Chuyển Điện Tích - Dẫn Điện Trong Dd Điện Ly_4T_RR

5/19/2018 3.2. Chng 4. S V n Chuy n i n Tch - D n i n Trong Dd i n Ly_4T_RR

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CHNG 4

S VN CHUYN IN TCH

DN iN


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Ni dung

4.1. Khi nim c bn4.2. dn in

4.3. Linh ion v linh ion H+- OH-

4.4. dn in ca dung dch in ly trong dung mi khc

4.5. S chuyn vn ca cc ion

4.6. Phng php o dn in v ng dng

4.7. Bi tp


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Vt th cng loi

4.1. Khi nim c bn

4.1.1. Vn chuyn in tch

Ionion

in t - in t

Thay i thnh phn ha hc

Khi dn in, ti b mt tip xc

Phn ng ha hc xy ra

Vt th khc loi

Ionin t

in t - ion


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Nhng dung dch in ly,

cht in ly nng chy, cckh ion ha.

Dn in do s chuyn vn

ca cc ion.

4.1.2. Phn loi dy dn

Da vo bn cht dn in,

FARADAY chia thnh 2 loi

Dy dn loi 1 Dy dn loi 2

Nhng dy lm bng kim loi

(ng, bc, nhm) hay bndn.

Dn in do s dch chuyn ca

cc in t (electron) v l trng

4.1. Khi nim c bn


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Cc m (Catod)

+ Electron chuyn t in cc (ni

cc M ngun in) n ion(trong dung dch)

+ Phn ng kh xy ra

Cu2+ + 2e = Cu

Fe3+ + e = Fe2+

2H2O + 2e = H2 + 2OH-

Cc dng (anod)

+ Electron chuyn t ion (trong

dung dch) n in cc (nicc DNG ngun in)

+ Phn ng kh xy ra

4OH- = O2 + 2H2O + 4e

Fe2+ = Fe3++ e

Zn = Zn2+ + 2e

4.1.3. S in phn

4.1. Khi nim c bn

Tngqu trnh

Dy dn loi 1(ANOD)

Dy dnloi2

Dy dnloi2 (CATOD)

q

q


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Trong :q : in lng i qua dung dch cht in ly (culng)I : cng dng in (A)

t : thi gian (s)k0: h s t l = /F

Lng cht thot ra hay bm ln b mt in

cc khi in phn, t l thun vi in lng i

qua dung dch .

m = k0.I.t = k0.q

4.1.4.nh lut Faraday

4.1. Khi nim c bn

nh lut Faraday 1


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nh lut Faraday 1


4.1. Khi nim c bn

chuynha mtnglnggamcamtchtbtkbnginphn cnmtinlngbngchnh sFARADAY.

Cho inlng1F qua th thu c1 lg

V k0= /FNn q = 1F m = k0x1F = ng lng in ha)


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nh lut Faraday 1


4.1. Khi nim c bn

Cu 179183

Bi tp:


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Khi cho cng mt in lng i qua cc dung

dch in ly khc nhau th lng cht thot ra

hay bm ln trn b mt in cc t l ving lng in ha ca n.

nh lut Faraday 2


4.1. Khi nim c bn

Cu 178Bi tp:


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1C (culong) = 1 ampe.giy

1F = 26,8 ampe.gi = 96484,520 96500 C


4.1. Khi nim c bn

Mt s chuyn i n v


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4.2. dn in

4.2.1. dn in ring

dn in ring ( -1.cm-1)

L dnincamtdung dchc thtch

V = 1cm3, ctgiahai inccphngsong

song c din tch nhnhau (cm2) v cch nhau 1

cm.

- in tr ring, in trca dy dn di 1cm, tit

din 1cm2

.

1


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sR;

R

1L

Mt s cng thc quan h

4.2. dn in

4.2.1. dn in ring

t:

s

k : hng s bnh in cc.

L.k


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L dnincamt th tch tnh theo cm3

changmtng lng gam chtin ly

nmgia hai incc phng song song cch

nhau 1cm.

dn in ng lng (cm2/lg. )

4.2. dn in

4.2.2. dn in ng lng


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Trong :

CN : nng ng lng

: dn in ng lng (cm2. -1.lg-1)

Cng thc tnh:

4.2. dn in

4.2.2. dn in ng lng

NC1000.


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4.6. PP o dn in - ng dng

4.6.1. Phng php o dn in

in trcadung dchKCl 0,02N 25oC trong mtbnh o

dninocl 457. Bitdninring cadung dch

l 0,0028 -1.cm-1. Dng bnh ny odnincadung dch

CaCl2cha0,555g CaCl2trong 1 lt c gi trl 1050. Xc nh

dninnglngcadung dchCaCl2?

V d1

Cu 233 238Bi tp:


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: dn in ng lng gii hn (dung dch v cng long)

A : gi tr thc nghim. Ph thuc T, P, dung mi, cht in ly

i vi cht in ly mnh, thch hp PT thc nghim Kohlrausch:

4.2. dn in

4.2.2. dn in ng lng

Trong :

nh lut th nhtKohlrausch

CA-


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i vi cht in ly mnh (= 1)

Vi cht in ly yu khi dung dch v cng long:

i vi cht in ly yu:

, +, -: dn in ng lng ti hn cc ion vi

dung dch v cng long (cm2/.lg)

4.2. dn in

4.2.2. dn in ng lng

Trong :

nh lut th haiKohlrausch


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4.2. dn in

4.2.2. dn in ng lng

Bit dnin ng lng gii hn 250C ca dung dch

HCl; CH3COONa v NaCl ln lt l 426,1; 91 v 126,5

cm2/.lg. Tnh caCH3COOH nhittrn?

V d2

Cu 160


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4.2. dn in

4.2.2. dn in ng lng

dninng lnggiihn250C cadung dch trong

nc C2H5COONa, NaCl v HCl ln lt l 85,9; 126,45 v

425,15 cm2/.lg.

a. Tnh caaxt propionic nhittrn?

b. Xc nhnngH+nubitdninnglngcaaxt ny bng41,3 cm2/.lg?

V d3


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4.2. dn in

4.2.2. dn in ng lng

i vi cht in ly yu:

Kho st qu trnh phn ly:

AB = A+ + B-

Ta c hng s phn ly nh sau:

C.

K2


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4.2. dn in

4.2.2. dn in ng lng

Quan h gia - C

Cht in ly mnh (PT thc nghim Kohlrausch):

Cht in ly yu (1 1), phng trnh nghim ng:

CA-

cK.

12

.C

1


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4.2. dn in

4.2.2. dn in ng lng

nh lut gii hn Debye - Huckel

nh lut gii hn Debye Huckel v h s hot (hay phng

trnh gn ng bc nht):

Phng trnh gii hn ca h s hot trung bnh c dng:

cI.l

2ii Z.Ag

cI..l ZZ.Ag


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4.2. dn in

4.2.2. dn in ng lng


cI.l

2ii Z.Ag

Nu dng nng molan, khi dung dch long Ci= mi.o

cI..l ZZ.Ag

mI.l

2ii Z'.Ag

mI..l ZZ'.Ag

250C, A = 0,509

o.A'A


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4.2. dn in

4.2.2. dn in ng lng


250

C, s gn ng bc hai c dng

I.B.1

I.l

aZ.Ag

2ii

I.B.1

I.l

aZ.Z.Ag

I1

I.l

2ii Z.AgI1

I.l

Z.Z.Ag


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4.2. dn in

4.2.2. dn in ng lng


Khi nng dung dch ln hn, vt qu nng gii hn ca nhlut gii hn (Pt gn ng bc hai):

250C:ang knh hu hiu trung bnh ion

A = 0,509 mol-1/2.dm-1/2

B = 0,329.107dm1/2.mol-1/2.nm-1

I.B.1

I.l

a

Z.Ag2ii

I.B.1

I.l

a

Z.Z.Ag


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4.2. dn in

4.2.2. dn in ng lng

Phng trnh Onsager

i vi cht in ly 2 1 trong nc, PT Onsager c dng:

i vi cht in ly 1 1 trong nc, PT Debye Onsager:

C.,

C

.T.T.2/12/3

- thm in mi; - nht; c nng


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Linh ion chnh l tc tuyt ica cc ion, n vcm2/von.giy.

Gi: +, -l tc chuyn ng cc iono+, o-l tc tuyt i cc ion

Ta c:

4.3. Linh ion Linh ion H+- OH-

4.3.1. Khi nim

: Cng in trng


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p dng nh lut Ohm v kt hp mt s biu thc khc, ta c

kt qu cui cng:


4.3.1. Khi nim

in ly mnh:

in ly yu:


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Linh ca cc ion trong dung dch nc thng c cng

ln khong 6.10-4 cm2/V.s

Ring linh ca H+v OH-rt ln:

+ H+: 36,3.10-4cm2/V.s

+ OH-: 20,5.10-4cm2/V.s


4.3.2. Linh ion ca cc ion H+

v OH-

Nguyn nhn


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dn in ca cc dung dch khc dung mi nc c

xc nh qua cc i lng Cion, tc chuyn vn v bncht dung mi.

Thng thng dn in ca chng nhhn so vi trong

nc, l do phn ly thp. (ngoi l NH3trong HCN)

4.4. dn in trong cc dung mi khc

nc.


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4.5. S chuyn vn cc ion

4.5.1. Khi nim

L tsgiain lngmang bimt loi ion

no qua tit din ca cht in ly v tng

inlngiqua titdindung dchinly .

S chuyn vn cc ion (s ti)

i

ii

q

qt


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4.5.1. Khi nim

Trong dung dchchahai loiion gmcation v anion th:

vv

v

vv

v

qq

qt

oo

o

vv

v

vv

v

qq

qtoo

o


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Anod

(+)

Catod

(-)

+ + + + + +

_ _ _ _ _ _

+ + + + + +

_ _ _ _ _ _

+ + + + + +

_ _ _ _ _ _

Vng I Vng II Vng III

+ + + + + +

_ _ _ _ _ _

(A)

(B)

(C)

+ + + + + +_ _ _ _ _ _ + + + + + +_ _ _ _ _ _ + + + + + +_ _ _ _ _ _

+

_

+ + + + +

_ _ _ _ _

- -

- -

- -

+ +

+ +

+ +

Anolit Catolit

4.5.2. Phng php Hittorf xc nh s chuyn vn

Ta c:

5

v

v

n

n

o

o

c

a

M hnh phngphp Hittorf


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4.5.2. Phng php Hittorf xc nh s chuyn vn

Tnh ton theo phngphp Hittorf

ca

a

ca

a

oo

o

mm

m

nn

n

vv

vt

Svnchuyncacc ion cxc nhtheo quan hsau:

ca

c

ca

c

oo

o

mm

m

nn

n

vv

vt


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4.5.3. Phng php ranh gii di ng

M hnh phngphp

MA

MA

x

b

b

+

MAchtinly cnnghin cu

MAchtinly chth

Mz+tcchuynvnlnhnMZ+

Dung dch khng mu o s dichuynbngchskhc x.


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4.5.3. Phng php ranh gii di ng

Tnh ton theo phngphp ranh giidi ng

q

CFSxt

Svnchuyncacation cxc nhtheo quan hsau:

Trong : x : ranh giidi ng,cm.

S : dintch titdinbnh, cm2.

C : slgtrong 1 cm3dung dch.

Khi dung dchc nngln,chnh xc khng cao

t= 1t+


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a

b

c

Rx R3

R2 R1d

N

G

Phng php cu Wheatstone

a

b

c

RxR3

R2 R1d

N

G

Hiu chnh in dung

Rc= 1/.C


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Ngi ta s dng cc bnh o o dn in, thay v o v S ca

in cc bnh th ngi ta o k = /S thng qua vic o in tr ca

cht bit chnh xc dn in ring. Sau , tnh nh sau:



xR

kL.k

Ngita thngdng dung dchinly chunKCl


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in trcadung dchKCl 0,02N 25oC trong mtbnh o

dninocl 457. Bitdninring cadung dch

l 0,0028 -1.cm-1. Dng bnh ny odnincadung dch

CaCl2cha0,555g CaCl2trong 1 lt c gi trl 1050. Xc nh

dninnglngcadung dchCaCl2?

V d1


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Trong in phn, tit kim nng lng v nng cao

cht lng sn phm.

Hm lng mui trong cc dung dch.

Xc nh bc axt

Xc nh ha tan

Php nh phn in dn trong phn tch.


4.6.2. ng dng php o dn


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4.6.2. ng dng php o dn

dn in ring ca dung dch AgCl bo ha 25oC bng

3,14.10-6-1.cm-1; dninring canccngnhittrn

l 1,60.10-6-1.cm-1. Bit dn in gii hn ca Ag+ v Cl- l

61,92 v 76,34 cm2/.lg. Xc nhho tan v tch s tan ca

AgCl 250C.

V d

Hngdn

Tnh AgCl; tnh AgCl

NC

1000. CN TAgCl = CAg+.CCl-


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4.6.2. ng dng php o dnPhp nhphn indn

H+

OH-

b

VNaOH

a

c

Na+

Cl-

ChunHCl bngNaOH


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4.6.2. ng dng php o dnPhp nhphn indn

ChunKCl bngAgNO3

Cl

b

a

c

NO3

Ag+

b'

K+


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4.7. BI TP

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3.2. Chương 4. Sự Vận Chuyển Điện Tích - Dẫn Điện Trong Dd Điện Ly_4T_RR