IN HA HCChng 2: S chuyn vn in tch trong dung dich in ly

Cc chuyn ng ca ion trong dung dchKhuch tn: do s khc bit v nng i lu: do s khc bit v nhit Chuyn vn: do trng in t

Tc chuyn ng ca ion: cm/sLinh ca ion: cm2/giy.VoltS ti ion dn in ring; dn in ng lng; dn in ng lng gii hnCc khi nim c bn

2.1. S dn in trong DDLChng 2: S chuyn vn in tch trong DDLDy dn loi 1 (kim loi, cht bn dn) : Dn in nh cc e v cc l trngDy dn loi 2 (DDL, cht in ly nng chy,..) : Dn in nh cc ion.

(Dy dn loi 1)

(Dy dn loi 2)

(Dy dn loi 1)

qqion (+)cationion(-)anion2Cl- Cl2 + 2eFe2+ Fe3+ + eCATODANODCu2+ + 2e Cu2H2O + 2e H2 + 2OH-Phn ng oxi haPhn ng khS in phn:

nh lut in phn Faraday

L 1: Lng cht b tch ra hay b ha tan khi in phn t l thun vi in lng i qua dung dch in ly

m= k0It = k0.qk0: ng lng in haq: in lng (C- culong= 1 Ampe.giy)2.1. S dn in trong DDL (tt.)Chng 2: S chuyn vn in tch trong DDL

nh lut in phn Faraday (tt)

L 2: Cng mt in lng i qua cc cht in ly khc nhau th lng cht b chuyn ha s t l thun vi ng lng ha hc ca chng

S Faraday: F= 96.500 C : in lng cn thit chuyn ha 1 ng lng gam (lg) ca mt cht bt k.

Hiu sut dng in: = mthc/mlt (

q: in lng (C- culong = 1 Ampe.giy)F = e.NANA: s Avogadro = 6.022 x 1023e = 1.602 x 10-19 Cng lngTrong phn in phn (Ha i cng)

dn in ring (/kai/) n v: - H SI: S.m-1 [ vi S= -1 : /siemens/] - hoc -1.cm-1 vi: 1 [-1.cm-1] = 100 [S.m-1]

Dy dn loi 1:

Dy dn loi 2: dn in ca 1cm3 (1ml) dung dch t gia 2 in cc phng song song c cng din tch S, cch nhau 1 cm.

V d :

2.2. dn inChng 2: S chuyn vn in tch trong DDLVi: : in tr sut

Cht (-1.cm-1) 180C

Ag615.000dd KCl 1N0,0098Paraffin

Cu WheatstoneTi sao s dng dng xoay chiu ? (trnh s in phn)Ti sao dng tn s dng cao ? (gim tr khng)

1. nh hng ca nhit n :

T = 25 [1- (T-25) + (T-25)2]T , 25 : dn in ring nhit T 0C v 250C, : h s nhit (ph thuc cht in ly)Phng trnh thc nghim: = 0,0163 (- 0.0174)

Chng 2: S chuyn vn in tch trong DDLCc yu t nh hng n dn in

Chng 2: S chuyn vn in tch trong DDL2. nh hng ca nng n :

Cht in ly mnh (vd: HCl): nng thp: chuyn vn ca ion khng ph thuc nng , nn khi C tng th cng tng. nng cao: m my ion lm gim tc chuyn vn ca ion, gim

Cht in ly yu (vd: CH3COOH):Mt m my ion nh, t nh hng n tc ca ion, t nh hng n nng cao: phn ly gim, dn in gim

dn in ng lng (-1.lg-1.cm2) dn in ca mt th tch dung dch cha 1 lg cht in ly nm gia 2 in cc phng song song, cng din tch, cch nhau 1 cm.2.2. dn in (tt)Chng 2: S chuyn vn in tch trong DDLVi C: nng ng lng (lg/l)

Chng 2: S chuyn vn in tch trong DDL nh hng ca C n :

Cht in ly mnh: gim chm khi C tng, quan h =f(C1/2) l ng thng.

nh lut Kolhrausch 1: = - A.C1/2 Vi: : dn in ng lng gii hn; A: h s thc nghim

Cht in ly yu: gim nhanh khi C tng, quan h =f(C1/2) l ng cong.Do tng tc gia cc ion: lc ht gia cc ion

nh lut Kohlrausch 1 dn in ng lng gii hn

Bng di y biu th s ph thuc dn in mol ca dung dch KCl vo nng 25oC.Tnh

C (mol/L)0.00050.0010.0020.0050.01m (-1m2.mol-1)0.012450.0123740.012270.0120650.011851

nh lut Kohlrausch 2 (v s chuyn ng c lp ca cc ion)

dn in ng lng gii hn ca cht in ly yu

Tnh dn mol ti hn ca dung dch LiBr v BaCl2 298K (116.8 v 279.8)Ion (-1cm2mol-1)Li+38.7Br-78.1Ba2+127.2Cl-76.3

Mt bnh o dn in khi cha dung dch HCl 0.01 M c in tr o c bng 468 , khi cha dung dch NaCl 0.001 M th in tr l 1580 , khi cha dung dch NaNO3 0.001 M, in tr l 1650 . dn in mol long v tn bng 121 -1cm2mol-1. Xc nh: dn in ca dung dch NaNO3 0.001 MHng s bnh (k=l/s)in tr ca bnh o khi cha HNO3 0.001 M v dn in mol long v tn ca dung dch HNO3.nh lut chuyn ng c lp ca ion trong dung dch: in tr R bng:

ng dng ca nh lut Kohlrauscha. Xc nh cho cc cht in ly yub. Xc nh in ly cho cc cht in ly yuc. Xc nh hng s in ly cho cc cht in ly yud. Xc nh tan ca cht t tan

V d: dung dch NaCl 0.1 N c dn ring l 0.0092. Nu dn ng lng ca Na+ v Cl l 43.0 v 65.0 ohm1 . Tnh phn ly ca NaCl. dn in ng lng ca NaCl

Tnh hng s cn bng phn ly cho cc cht in ly yunh lut pha long Ostwald

Cc k hiu v gii thch:+ , - : tc chuyn vn ca cation, anion (cm/s) ph thuc bn cht, nng , T, nht, cng in trng ngoi,

0+ , 0- : tc tuyt i hay linh cation, anion (cm2.s-1.V-1) + = 0+.(E/l) ; - = 0-.(E/l) [E/l: cng in trng ngoi]

C, : Nng ng lng (lg/l), phn ly ca cht in ly C. /1000 (lg/cm3) : S cation, anion trong 1cm32.3. Tc vn chuyn- dn inChng 2: S chuyn vn in tch trong DDL

S lg cation, anion chuyn vn qua tit din S (cm2) trong 1s:Chng 2: S chuyn vn in tch trong DDLC. /1000 (lg/cm3)S (cm2)cationanionC. /1000 (lg/cm3)2.3. Tc vn chuyn- dn in (tt)

V 1 lg mang in lng 1F nn tng in lng chuyn bi cation, anion qua tit din S (cm2) trong 1s:Chng 2: S chuyn vn in tch trong DDLTheo nh lut Ohm:Do : = .F.(0+ + 0-)2.3. Tc vn chuyn- dn in (tt)

Vi cht in ly mnh (=1): = F.(0+ + 0-) = + + -Vi cht in ly yu ( (baz) >> (mui)

2.3. Tc vn chuyn- dn in (tt)

Linh ca ion H+ v OH- :oH+ v oOH- rt ln so vi o ca cc ion khc.

Nguyn nhn: Di in trng ngoi, ion H+ v OH- chuyn vn trong nc theo c ch dy chuynChng 2: S chuyn vn in tch trong DDLH+ + H2O H3O+2.3. Tc vn chuyn- dn in (tt)

Ionoi .105 (cm2.s-1.V-1)(dd v cng long 25oC)H+363,0OH-205,0Na+52,0Cl-79,0

Xc nh bn knh ion hydrat ha ca Li+ v Na+ trong dung dch v cng long bit linh ca chng bng 40.1 x 10-5 v 51.9x10-5 m2.s-1.V-1, nc c nht 0.89 cP. Bit 1P = 0.1N.s.m-2 = 0.1 kg.m-1.s-1Na+ v Li+ c cng in tch, song Li+ c kch thc nh hn Na+ nn b hydrate ha mnh hn

Cc yu t nh hng n dn gii hn 1) Bn cht ca cc ion (1) in tch (4) C ch (3) Cc c tnh in(2) Bn knh

dn mol gii hn ca cc ion

ionsr / nm102 mionsr / nm102 mH+--3.4982OH--1.98Li+0.680.387F1.230.554Na+0.980.501Cl 1.810.763K+1.370.735Br 1.960.784Mg2+0.741.061CO32 --1.66Ca2+1.041.190C2O42---1.48Sr2+1.041.189Fe(CN)63 --3.030Al3+0.571.89Fe(CN)64 --4.420Fe3+0.672.04La3+1.042.09

C ch chuyn vn ca H+ v OH- C ch Grotthus (1805)

2) nht ca dung miBng. nht ca dung mi

acetoneMethyl alcoholEthyl alcohol / mPas0.3160.5471.200K+0.00820.00540.0022Li+0.00750.00400.0015

nh lut StokesZ: s in tche: in tch ca eE: in trng ngoi: nhtR: bn knh lp solvat haNu E = 1V/cm v = vo: linh ion

nh hng ca nht n dn in ng lng- Mi dung mi c 1 nht xc nh- Cng 1 cht in ly, cc dung mi khc nhau, dn in ng lng s khc nhau.

Nu dd CL ch cha 2 loi ion:Chng 2: S chuyn vn in tch trong DDL2.4. S chuyn vn ca ion (S ti)(Transport number, transference number)S chuyn vn ca ion: L t s gia in lng mang bi ion qua tit din ca dd CL v tng in lng i qua tit din .VNhn xt: ti s ph thuc vo ion cng cp vi ion .

Cht in lyNaClHClt-(Cl-)0.6040.170

Cc thng s nh hng n s ti 1) Nhit Bng S ti ca K+ trong dung dch KCl cc nng v nhit khc nhau

T / oC0.0000.0050.010.02150.49280.49260.49250.4924250.49060.49030.49020.4901350.48890.48870.48860.4885

2) Cc ion cng tn ti trong dung dch

Cht KClKBrKIKNO3 t+0.49020.48330.48840.5084ChtLiClNaClKClHCl t0.67110.60800.50980.1749

Chng 2: S chuyn vn in tch trong DDL2.4. S chuyn vn ca ion (S ti) (tt)Phng php Hittorf xc nh s chuyn vn: Trc khi in phnTrong khi in phnSau khi in phnNguyn tc: xc nh ti thng qua s bin thin nng ion vng anolit v vng catolit.V d: in phn dd HCl, in cc tr

Chng 2: S chuyn vn in tch trong DDL2.4. S chuyn vn ca ion (S ti) (tt)Phng php Hittorf xc nh s chuyn vn (tt) Lng cht in ly gim: - anolit : na - catolit : nc Lu : Do s solvat ha, dung mi cng di chuyn theo ion c s khc bit Ti (thc) v ti (biu kin, theo PP Hittorf). Trong cc dd long, s khc bit ny t.

Phng php ranh gii di ng xc nh s chuyn vnMA, MA c chung anion. MA l cht cn nghin cu. MA l cht ch th. Cation M c tc chuyn vn nh hn M ranh gii phn chia di chuyn

Khi cho in lng Q coulomb i qua, ranh gii di ng 1 khong x, din tch mt ct ca ng l S:xSz+FC = t+Q

V d:Trong thc nghim theo pp ranh gii di ng vi dung dch 0.100N KCl v dng 0.065 N LiCl ng vai tr nh cht ch th, dng in khng i I = 0.005893 A i qua dung dch trong 2130 s, xc nh ranh gii di ng 5.6 cm trong ng c tit din 0.1142 cm2. Tnh s chuyn vn ca ion K+ v Cl-

xc nh s ti ca ion ng v ion clo, ngi ta in phn dung dch cha 26.9 g/L CuCl2 vi cc in cc than. S phn tch 0.5 L dung dch khu catot sau in phn thy c 3.95 g Cu, cn trong 0.5 L dung dch khu anot sau in phn c 4.75 g Cu. Tm s ti ca ion ng v cloLng ng c trong 0.5 L dung dch CuCl2 trc in phn: gim lng Cu khu catot v anot l:

Chng 2: S chuyn vn in tch trong DDL2.5. Phng php o dn in & ng dng Phng php o dn inDng cu Wheatstone:Khi G=0: R1/R2= R3/Rx

Dng bnh o dn

Chng 2: S chuyn vn in tch trong DDL2.5. Phng php o dn in & ng dng (tt) ng dngXc nh nng lng tiu th trong qu trnh in phnXc nh hm lng mui trong cc dung dch (vd: trong ni supde)Xc nh bc ca acidXc nh ha tan ca cc cht kh tanTrong phn tch: php nh phn in dn

Chng 2: S chuyn vn in tch trong DDL2.5. Phng php o dn in & ng dng (tt) Php nh phn in dnNguyn tc chung: Do dn in c bit ln ca ion H+ v OH- so vi cc ion khc m c s thay i dn in ca dd. V d: