lv giang day mot so noi dung hh thpt - dien hoa hoc

5/28/2018 LV Giang Day Mot So Noi Dung HH THPT - Dien Hoa Hoc

- 1 -

PHN I. MUI.1. L do chn ti.

Hin nay, vic i mi ni dung v phng php dy hc l mt trong nhng vn

c rt nhiu ngi quan tm. Mt nhim vcbn ca dy hc nh trng l m

bo cho hc sinh nm vng c kin thc, lm cho hc sinh hiu ng bn cht ca

mt vn . iu ny i hi ngi gio vin cn phi c mt phng php sphm

vng chc, kin thc chuyn mn cao. Bn cnh i hi hc sinh phi tch cc hn

trong hc tp tmnh c thchim ly tri thc khoa hc.in ha hc l phn ni dung kin thc rt quan trng trong ni dung chng trnh

ha hc phthng hin nay. c manh nha lp 9 bc trung hc cs, v trnh by

rt rng bc trung hc phthng. Chyu nm phn i cng vkim loi ca lp

12. y l phn l thuyt csrt quan trng nghin cu tm hiu tnh cht ca kim

loi v ion kim loi trong dung dch.

V vy, trong qu trnh truyn t cn phi pht huy tnh tch cc, nng lc tduy,

sng to ca hc sinh.in ha hc c nhng ng dng g? Chng tun theo qui lut nhthno? c bit

vic dy v hc chng chng trnh trung hc ph thng ra sao? L mt gio vin

tng lai bn cn chun bnhng g? Cch trnh by ca bn i vi hc sinh ra sao?.

Vi nhng l do cbn , ti quyt nh chn ti nghin cu: Ging dy mt

sni dung in ha hc trng trung hc phthng.

I.2. Mc ch nghin cu.

Tm hiu ni dung in ha hc v phng php ging dy ni dung trong chng

trnh trung hc phthng.


- 2 -

I.3. Nhim vca ti.

- Nghin cu nhng csxy dng v nhng yu tnh hng n hot ng hahc ca kim loi theo in ha hc

- Tm hiu ni dung, cu trc chng trnh in ha hc trng trung hc ph

thng.

- Thit kmt sgio n ging dy phn in ha hc trng trung hc phthng.

- Tm hiu thc trng.

I.4.Khch th, i tng v phm vi nghin cu.

- Khch th. Cc ti liu c lin quan.

- i tng. Gio vin hc sinh trung hc phthng

- Phm vi nghin cu: Trng THPT, Gio vin, Hc sinh, V cc ti liu c lin

quan.

I.5. Phng php nghin cu.

- Nghin cu l thuyt.

- Nghin cu thc tin.

- Thc tp ging dy.

- Thng k ton hc


- 3 -

PHN II. NI DUNG

CHNG I. MT SCSI.1. Csl lun ca shnh thnh khi nim in Ha Hc.

I.1.1. Tm quan trng ca vic hnh thnh khi nim in ha hc trng

THPT.

Trong qu trnh khi qut ha nhng kin thc vcc cht ring bit v vnhng bin

ha ca chng, nhng khi nim c bn v ha hc dn dn xut hin. Nhng khi

nim trthnh im ta, l vkh cho vic tip tc nghin cu cc nguyn tv cc

hp cht ha hc. Lc , nhng khi nim cbn dn dn c cthha thm, o

su thm v ngy cng phn nh ng ng hn cc mt phc tp ca vn .

in ha hc l phn kin thc csquan trng c c u chng i Cng

Kim Loi sch gio khoa ha hc 12. Lm tin cs, v l l thuyt cho cho

vic tm hiu tnh cht ha hc ca kim loi, ion kim loi trong dung dch.

V thtrong vic ging dy ha hc, ngi gio vin cn ch rn luyn cho hc sinh

thi quen nhn thc cc skin thc nghim vphn ng ha hc di nh sng ca

ca cc l thuyt khc nhau, trong c l thuyt in ha hc.

Vic vn dng l thuyt in ha hc trong dy hc ha hc khng nhng c ngha

ht sc to ln i vi vic nghin cu tnh cht ha hc ca cc cht, hp cht m cn

ci vi vic hthng chng cng vi nhng l thuyt ha hc khc.

I.1.2. Ni dung nghin cu in Ha Hc chng trnh trung hc phthng

Mun hnh thnh c hiu qucho hc sinh mt khi nim hoc hthng khi nim no

, ng

i gio vin c

n xt k

nhi

u m

t c

a khi ni

m tr

c khi ti

n hnh gi

ng d

y.

Mun xt vn ny cn phi xut pht tmc tiu o to ca cp hc v nhim v

c tr dc ca mn hc tc l phi da chc chn vo ni dung chng trnh ca b

mn . Ni chung vic nghin cu shnh thnh ca ni dung kin thc in ha hc

cn tri qua cc bc sau.


- 4 -

- Xt vtr v tm quan trng ca ni dung in ha hc trong chng trnh bmn.

- Xt cu trc ca ni dung in ha hc: in ha hc bao gm nhng ni dung no

m ta phi hnh thnh cho hc sinh.Cn da vo trnh pht trin chung ca hc sinh m xt kkhi lng, mc nng

hay su ca nhng kin thc . Nhvy y c hai bc phi thc hin.

+ Xt cu trc ca ni dung in ha hc theo quan im hin i ca khoa hc

(da vo chng trnh ha hc bc i hc)

+ La chn kin thc v knng, kxo cn truyn thcho hc sinh phthng cn

cvo trnh pht trin ca h.

- Phn tch shnh thnh ni dung in ha hc trong sut chng trnh cTHCS v

THPT.

Trong tng giai on, ni dung kin thc in ha hc c hnh thnh v pht trin ra

sao, c nhng yu cu g vckin thc ln knng kxo. y cn phi xem xt

tng kha cnh ca khi nim, tc l nhng kin thc cbn l thnh phn cu trc ca

ni dung in ha hc c hnh thnh v pht trin nhthno?

- Tm ra nhng bin php s phm hiu nghim nht thch hp vi tng giai on,

nhm thc hin c yu cu ring ca tng giai on cng nhyu cu chung v

vic hnh thnh ni dung in ha hc

I.2. Csl thuyt ca khi nim in ha hc.

I.2.1. Phn ng oxi ha - kh.

Phn ng oxi ha - kh l loi phn ng trong c s chuyn electron hon ton

(hoc mt phn) tnguyn t(hay ion) ny sang nguyn t(hay ion) khc. Kt qul

trong phn ng c sthay i soxi ha ca mt hoc vi nguyn t.

- Cht oxi ha l cht cha nguyn tnhn electron.- Cht khl cht cha nguyn tcho electron- Qu trnh cho electron ca cht khc gi l soxi ha.- Qu trnh nhn electron ca cht oxi ha c gi l skh.


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V d: ++++ ++ 2432 22 FeSnFeSn

[ ]Kh

SneSn ++ 42 2 (soxi ha) ;

[ ]

3 21Fe e Fe

Ox

+ ++ (skh)

I.2.2. Cp oxi ha kh.

Hai ion +3Fe v +2Fe c gi l mt cp oxi ha kh lin hp, trong +3Fe l dng

oxi ha , +2Fe l dng khlin hp ca +3Fe .

Tng qut:

- Dng oxi ha nhn electron dng khlin hp.- Dng khcho electron dng oxi ha khlin hp.

Vi mt phn ng oxi ha khbt k, ta lun c:

Kh (2) Ox(2) + ne soxi ha

Ox(1) + ne Kh(1) skh

Ox(1) + Kh(2) Kh(1) + Ox(2)

Ta nhn thy tnh oxi ha ca dng oxi ha cp thnht Ox(1) mnh hn tnh oxi ha

ca dng oxi ha cp oxi ha thhai Ox(2). nh gi mnh ca mt cp oxi ha

khlin hp, ngi ta sdng i lng thin cc.

I.2.3. Thin cc Phn loi in cc Cch xc nh.

I.2.3.1.Thin cc

Mt thanh kim loi nhng vo dung dch mui ca n to thnh mt in cc

V d: Thanh Zn nhng vo dung dch ZnSO4 to thnh in cc Zn.

Gia kim loi v dung dch bao quanh n pht sinh mt hiu sin thgi l thin

cc

ne


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I.2.3.2. Phn loi in cc

1.in cc kim loi.

Khi nhng mt thanh kim loi M vo nc th do tc dng ca cc phn tc cc canc, cc ion kim loi nM + btch ra khi bmt kim loi to thnh cc ion kim loi

hirat, cn cc electron li trong thanh kim loai. Kt qul thanh kim loi tch in

m, cn dung dch tch in dng, to nn cn bng ng sau:

. ( ) ( )nM aq ne trong thanh kimloai M tt aq+ + +

2. in cc oxi ha kh.

in cc oxi ha kh l mt in cc gm mt kim loi trnhng trong dung dch

cha mt cp oxi ha kh. Kim loi trl kim loi m ion ca n khng chuyn vo

trong dung dch, thng dng platin hoc vng.

V d:Platin nhng trong dung dch cha cp oxi ha kh3

2Fe

Fe+

+ (c thdng dung

dch FeCl3v FeCl2).. Kt qul tn ti cn bng ng sau:

3 2Fe e Fe+ ++

Vy ranh gii gia kim loi v dung dch tn ti mt lp in tch kp v sinh ra mt

hiu sin thtng tnhin cc kim loi.

Thin cc ca in cc loi ny phthuc vo bn cht ca cp oxi ha kh, vo

tsnng ca dng oxi ha v dng khv vo nhit .

3. in cc hiro chun.

Gi trtuyt i ca hiu sin thsinh ra gia kim loi lm in cc v dung dch

in cc khng thxc nh c mt cch trc tip, nn phi quy c ly mt in

cc no lm chun v gn cho n mt gi trhiu sin thso snh vi cc

in cc khc.

in cc c chn lm chun l in cc hiro chun. y l loi in cc oxi ha

khgm dy platin c khnng hp phtt hiro (dng kh), c nhng trong dung

dch H2SO4l dung dch cha dng oxi ha H3O+


- 7 -

Hnh I.1. Cu to in cc hiddro chun.

Khi tn ti cn bng sau: 3 2( ) 22 2kH O e H H O+ + +

in cc hiro chun phi c iu kin chun sau:

- p sut (chnh xc hn l hot p) ca kh hiro bng 1atm.- Nng (chnh xc hn l hot ) ca H3O+bng 1mol/l- Thin cc ca in cc hiro tiu chun nhit bt k c quy c bng

0,00V v c k hiu nhsau: 0 32

0,00H O VH+

=

Gi trny c gi l thin cc hiro chun hoc thoxi ha khchun hoc th

khchun ca cp oxi ha kh 32

H OH

+

.

I.2.3.3. Cch xc nh thin cc chun ca mt cp oxi ha kh

so snh c thin cc ca cc loi in cc khc nhau cn phi c nhng quyc thng nht cho cc loi in cc. Nhng quy c ny nhsau:

- iu kin chun ca cc in cc:Mt in cc c coi l iu kin chun khi

nng (chnh xc hn l hot ) ca cu ttham gia phn ng in cc bng 1mol/l,

nu l cht kh th p sut (chnh xc hn l hot p) ring phn ca n bng 1atm.

- Chiu ca phn ng in cc l chiu ca qu trnh kh.

ox + ne kh

y: ox dng oxi ha; kh dng kh.

- mt nhit xc nh .

xc nh thin cc chun ca mt in cc no , ngi ta thit lp mt pin

gm in cc chun cn xc nh thin cc v in cc hiro tiu chun ri o hiu


- 8 -

sin th ln nht gia hai in cc. Hiu sin th ln nht ny l thin cc

chun ca in cc xc nh hay cn gi l thkhchun ca cp oxi ha khxc

nh (v thca in cc hiro chun c quy c bng 0,00V). Thkhchun ca

cp oxi ha khnhit xc nh c k hiu l ( )0 ox kh

Thkhchun o c sc gi trdng nu in cc cn o cao hn thin cc

hiro chun, ngha l in cc cn o thin cc l in cc dng (catot) ca pin v

ngc li n c gi trm.

I.2.4. Thin cc chun ca kim loi.

L thca bn phn ng khi tt ccc thnh phn ca ngn in cc u iu kin

tiu chun. Ghp in cc kim loi tiu chun vi in cc hydro tiu chun thnh mt

nguyn t Galvani, o sut in ng ca nguyn t v xc nh chiu ca dng

in.

V d:o thin cc tiu chun ca in cc Zn. Lp pin gm in cc km tiu

chun v in cc hyro tiu chun ([H+] = [Zn2+] = 1M)

(-) Zn Zn2+H+H2(Pt) (+)

Thc nghim cho thy phi kim hot ng th in cc hyro tiu chun l cc dngv in cc km tiu chun l cc m. Sut in ng ca pin: E0= 0,763V

E0pin = 02H+/ H2-

0Zn2+/ Zn= 0,763V

Vy 0 Zn2+/ Zn= 02H+/ H2- E

0pin = 0 0,763 = -0,763V

Bng cch tng tngi ta xc nh c thin cc tiu chun ca cc in cc

kim loi v cc cp oxi ha khri xp thnh bng thin cc tiu chun ca cc cp

oxi ha kh( Xem phlc 1)


- 9 -

I.2.5. Cc yu tnh hng n thin cc.

I.2.5.1. Phng trnh Nerst.

Trong cc phn trn, ta nhiu ln nhn mnh rng, 0E l thca cc phn ng trong nng dung dch v p sut ca cc kh tham gia phn ng oxi ha khu bng

n v.

Khi thay i nng dung dch v p sut ca cc kh th trsthE skhc vi trs

0E chun.

Nhng nh hng trn c nh ha hc v vt l hc ngi c l Walter Nerst tm

ra v khi qut n nhsau:

QnF

RTEE ln0 =

250C, hay T= 298K ta c.

Qn

EE lg059,00 =

Vi phn ng tng qut sau: aA + bB = cC + dD

th ta c:[ ] [ ]

[ ] [ ]ba

dc

BA

DCQ=

E c thl thca in cc hoc thca phn ng.

I.2.5.2.nh hng ca nng hay hot .

Tphng trnh Nerst :[ ] [ ]

[ ] [ ]0 0,059 lg

c d

a b

C DE E

n A B=

Ta thy E phthuc vo nng ca cc cht A,B,C,D

1/ Xt trng hp E l thin cc.Ta c: aOxh + ne bKh

Phng trnh Nerst:[ ]

[ ]a

b

Oxh

Kh

nlg

059,00 =

2/ E l thca phn ng.


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Xt phn ng: aOx2 + bKh1 = cKh2 + dOx1

[ ] [ ]

[ ] [ ]ba

dc

KhOx

OxKh

n

EE12

120 lg059,0

= ; Vi 000

1

1

2

2

Kh

Ox

Kh

OxE =

Kt lun: T hai biu thc trn ta thy nng dng oxi ha v dng kh nh

hng rt ln n gi tr , E

I.2.5.3. nh hng ca p sut

Xt phn ng sau 250C.2

02( ) ( ) 2

2 2 ; 1,36k aq ClCl

Cl e Cl V + =

iu kin trn ta c:[ ] ( )

V

p

Cl

Cl

567,1

10

10lg

2

059,036,1lg

2

059,0 32

0

2

===

Kt lun:p sut nh hng kh mnh n thin cc ca phn ng.

I.2.5.4. nh hng ca pH.

Nu trong qu trnh oxi ha kh, c ion H+hoc OH- tham gia th th ca phn ng

cng phthuc vo pH ca chng.

Trung hp tng qut: Khi tt ccc cht tham gia phn ng oxi ha kh(trH+)

u c nng v p sut bng n v, ta c biu thc.

0 0,059 mpHn

=

m, Sion H+hoc OH-trong phng trnh chung

n; Selectron trao i trong phng trnh chung

Kt Lun:pH nh hng ln n thca phn ng.

I.2.5.5. nh hng ca nhit .

mt nhit bt k ta c:

)1(pT

GHG

+= v )2(nFEG =

T(1) v (2) ta c:T

ET

nFE

+

= hoc

dT

dET

nFE +

=


- 11 -

VidT

dEl hsnhit ,

Kt lun:Nhi

t

nh h

ng l

n

n thc

a phn

ng.I.2.5.6. nh hng ca sto kt ta.

Xt phn ng sau 250C: VFeeFe aqaq 77,0;102

)(3

)( +=+ ++

Tnh ca bn phn ng khi cho vo dung dch trn nng [OH-] = 1M

- iu kin trn ta c:[ ][ ]

[ ][ ] 36333)(

1422

2)(

10

10

+

+

==

==

OHFeT

OHFeT

OHFe

OHFe

Khi ta c:[ ][ ]

VFe

Fe528,0

1010

lg1059,0

77,0lg1059,0

36

14

3

20 ===

+

+

Kt lun: Do c s to kt ta lm cho kh nng kh ca ion Fe2+ tng ln rt

nhanh.

I.2.5.7. nh hng ca sto phc

Xt phn ng sau: VFeeFe 77,0;1 023 =+ ++

Nu khi thm vo htrn mt phi tc khnng to phc cht bn vi cdng oxiha v dng khth ta c. ( )[ ] ( )[ ] + 46

36 1 CNFeeCNFe

Ta c cn bng:( )[ ]

( )[ ] 37246

44336

10.25,1;6

10.25,1;62

3

+

+

=+

=++

+

FeCb

FeCb

KCNFeCNFe

KCNFeCNFe

Khi ta c:( )[ ]

( )[ ]

[ ][ ]+

+

+=+

+

2

300 lg059,0

3

2

46

36 Fe

Fe

FeFe

CNFeCNFe

V ( )[ ] ( )[ ]

=

4

6

3

6 CNFeCNFe

iu ki

n chu

n. ( )

( )

364

6

0,36Fe CN Fe CN

V

=

Vy: Th chun ca phn ng ny gim t 0,77V xun cn 0,36V v

( )[ ] 36CNFe bn hn ( )[ ] 4

6CNFe


- 12 -

I.2.6. Chiu ca phn ng oxi ha - kh

Trong dung dch nc, chiu ca phn ng oxi ha khc xc nh da vo cng

thc sau:G nFE = (1)

E c tnh nhsau: ( ) ( )1 1 2 2ox kh ox khE =

Trong ( )1 1ox kh l thkhca cp oxi ha khc dng ox1vbn phi ca

phn ng, cn ( )2 2ox kh l thkhca cp oxi ha khc dng kh2vbn tri

ca phn ng, ngha l ng vi phn ng sau:

1 2 1 2ox oxkh kh+ +

Nu ( ) ( )1 1 2 2ox kh ox kh > th E > 0 v theo cng thc (1) ta c 0G < ngha l

phn ng i theo chiu thun. Ngc li nu ( ) ( )1 1 2 2ox kh ox kh < th phn ng i

theo chiu nghch.

Khi thc hin phn ng iu kin chun th: 0 0G nFE = (2)

Vi ( ) ( )0 0 01 1 2 2ox kh ox khE =

I.2.7. Hng scn bng ca phn ng oxi ha kh

Tcng thc: 0 0 lnG nFE RT K = = . Ta c: 0 lnRT

nE KF

=

250C biu thc tr thnh:0

lg0,059

nEK= , K l hng scn bng ca phn ng.

I.2.8. Ha hc v dng in

I.2.8.1. Pin

Pin l mt loi ngun in ha ph bin dng cho nhiu mc ch. Trong pin, nng

lng phn ng ha hc bin thnh in nng.

1. Sc in ng ca pin

nh ngha. Sut in ng ca pin l gi tr(trstuyt i) ca hiu s


- 13 -

in thln nht gia hai in cc ca pin. N c tnh bng cng thc.

0E + = >

y: E sut in ng ca pin(V); + - thkhca in cc dng(V); - th

khca in cc m (V),

Nu pin c cu to bi hai in cc iu kin chun th sut in ng chun l:

0 0 0 0E + = >

2. Pin in ha

Pin Lclngse

- in cc m (anot) ca pin l Zn (ng thi l vbc pin).- in cc dng (catot) ca pin l mt thanh ch c bao bc bi mt hn hp MnO4

v bt than.

- Cht in li y l 4 2,NH Cl ZnCl dng bt nho. Cc qu trnh xy ra trong pin

nhsau: in cc Zn cung cp ngun electron.

Qu trnh oxi ha : 2 02 ; 0,76Zn Zn e V+ + = +

Electron chuyn ng ra mch ngoi tin cc m (Zn) n in cc dng, to ra

dng in. Qu trnh kh: 04 2 3 22 2 2 ; 1,04MnO H e Mn O H O V++ + + =

Sc in ng ca pin l.

2 0

04 2 3 2

2 04 2 3 2

2 ; 0,76

2 2 2 ; 1,04

2 2 ; 1,80pu

Zn Zn e V

MnO H e Mn O H O V

Zn MnO H Zn Mn O H O E V

+

+

+ +

+ =

+ + + =

+ + + + =

Sca pin nhsau: ( ) ( )4 2 2, ,Zn NH Cl ZnCl MnO C +

I.2.9. Sin phnI.2.9.1 nh ngha

Sin phn l qu trnh oxi ha - khxy ra bmt cc in cc khi cho dng in

mt chiu i qua hp cht nng chy hoc dung dch cht in li.


- 14 -

Vy : Sin phn l qu trnh bin in nng thnh ha nng.

Hnh I.2. Sin phn.

- Phn ng oxi ha - khxy ra in cc khi in phn.

+ Cc cation (ion dng) vcatot (cc m), ti xy ra qu trnh nhn electron to

ra sn phm (cht oxi ha)

+ Cc Anion (ion m) vanot (in cc dng), ti anion nhng electron to ra

sn phm (cht kh).

I.2.9.2. Cc dng in phn

1. in phn nng chy

- in phn cc cht nng chy (mui, Al2O3)

catot ion dng kim loi nhn electron.

anot ion m nhng electron.Trong in phn mui nng chy, bn thn mui nng chy l cht in li, cc ion b

ht v cc in cc tri du: Cation b ht v catot (cc m) v anion v anot (cc

dng)

2. in phn dung dch

Khi in phn dung dch cht in phn c nhiu cht oxi ha v cht khth xxy ra

oxi ha khln lt cc in cc theo thtu tin.

a/ Qu trnh xy ra Catotxt xem cation kim loi Mn+ hay H2O bkhcatot, trc ht cn so snh thkh

ca hai cpnM

M+

v2

HH

+


- 15 -

Trong mi trng trung tnh (pH = 7) ta c: 72

0,059lg10 0, 423H VH+ = =

Nu cation kim loi c ( )n

M M+

ln hn nhiu so vi -0,413V th trong dung dch

trung tnh ion Mn+bkhcatot khi in phn thnh kim loi: ( )nM ne M tt+ +

Nu cation kim loi c ( )nM

M+

nhhn nhiu so vi -0,413V th ion Mn+skhng

bkhm H+ca nc bkhthot ra H2.

2( )2 2 2kHOH e H OH+ +

Cui cng nhng kim loi c

( )

nM

M

+

gn vi gi tr-0,413V nhZn, Cr, Fe, Cd,

Ni ty thuc vo nng ca dung dch v iu kin in phn m kim loi hay H2

thot ra catot.

b/ Qu trnh xy ra Anot tr.

Trong mi trng kim xy ra qu trnh oxi ha cc anion OH-

2 24 4 2OH O e H O + +

Trong mi trng axit hoc trung tnh xy ra soxi ha H2O

2 22 4 4H O O e H+ + +

Cc anion c cha oxi ca axit khng c khnng boxi ha hoc soxi ha chng

xy ra thrt cao. Khi in phn dung dch ca axit khng cha oxi v mui ca n

(trHF v mui florua) th anion ca axit boxi ha anot tr.

c/ Qu trnh xy ra anot tan.

Khi in phn vi anot tan c ba qu trnh oxi ha cnh tranh nhau anot. l soxi

ha nc to ra oxi, sphng in ca anion cht in li v soxi ha kim loi lmanot. Nu kim loi lm anot c thkhnhhn hai cp oxi ha khkia th squan

st thy soxi ha kim loi : ( )n

ttM M ne+ +


- 16 -

Trong trng hp ngc li sxy ra s thot ra kh oxi hoc soxi ha anion cht

in li nhtrn xt trn.

cc dng c cc anion v nhng electron theo tht.2 - 2

3 4OO ....Cl Br S CH C OH SO > > > > >

3. nh lut Faraday.

Tkt qunghin cu Faraday thit lp c nh lut in phn sau y.

Khi lng cc cht to thnh in cc khi in phn tlvi lng in i qua cht

in phn v tun theo cng thc sau:AQ AIt

mnF nF

= =

I.2.10. Sn mn kim loi.I.2.10.1. Khi nim. Sph hy vt liu kim loi gy nn bi cc cht mi trng

xung quanh gi l sn mn kim loi.

I.2.10.2. Phn loi.

1.n mn ha hc

c im ca n mn ha hcl khng pht sinh dng in ( khng c cc in cc )

v nhit cng cao th tc n mn cng nhanh.

Th d: 2 2 3 23 4 4Fe H O Fe O H + = +

Bn cht ca n mn ha hcl qu trnh oxi hakh, trong cc electronca kim

loi c chuyn trc tip sang mi trng tc dng.

2.n mn in ha hc

Qu trnh ha tan kim loi lin quan n sxut hin cc dng in vi m, n cc qu

trnh Anot v Catot gi l hin tng n mn in ha.

Kim loi lun ch

a cc t

p ch

t. Kim lo

i v cc t

p ch

t trong kim lo

i c

ng nh

mi

trng to thnh cc cp in cc vi thin cc khc nhau.

Trong cc qu trnh Anot, kim loi boxi ha trthnh cc ion dng:

nM M ne+ +
http://www.onthi.com/?a=OT&ot=LT&hdn_lt_id=747#3http://www.onthi.com/?a=OT&ot=LT&hdn_lt_id=747#3http://www.onthi.com/?a=OT&ot=LT&hdn_lt_id=747#3http://www.onthi.com/?a=OT&ot=LT&hdn_lt_id=747#3http://www.onthi.com/?a=OT&ot=LT&hdn_lt_id=747#3http://www.onthi.com/?a=OT&ot=LT&hdn_lt_id=747#3http://www.onthi.com/?a=OT&ot=LT&hdn_lt_id=747#3http://www.onthi.com/?a=OT&ot=LT&hdn_lt_id=747#3http://www.onthi.com/?a=OT&ot=LT&hdn_lt_id=159#3http://www.onthi.com/?a=OT&ot=LT&hdn_lt_id=142#4http://www.onthi.com/?a=OT&ot=LT&hdn_lt_id=742#0http://www.onthi.com/?a=OT&ot=LT&hdn_lt_id=742#0http://www.onthi.com/?a=OT&ot=LT&hdn_lt_id=142#4http://www.onthi.com/?a=OT&ot=LT&hdn_lt_id=159#3http://www.onthi.com/?a=OT&ot=LT&hdn_lt_id=747#3http://www.onthi.com/?a=OT&ot=LT&hdn_lt_id=747#3


- 17 -

Trong cc qu trnh Catot, cc tc nhn oxi ha nhn cc in tny to nn phn ng

kh: Chng hn: 2

2 2

2 2

4 4 2

H e H

O H e H O

+

+

+

+ +

Kt qul cc kim loi bha tan, bn mn.

I.2.10.3. Cc phng php bo v.

1. Phng php to lp ph.

Cht phc dng c thl kim loi bn i vi mi trng nh; Ni, Zn, Cr, Sn, Cd,

Al, Ag, Au.., Nhng cht phkhng phi l kim loi, thng l sn, men, nha.

2. Bo vbng phng php in ha

Sdng phng php catot. Nu ngi ta ni Fe vi Zn chng hn bng mt dy dn

th hin tng n mn Fe sc hn chv i vi cp kim loi Fe Zn th Fe givai

tr l mt Catot. 2 20 00,44 ; 0,76Fe ZnFe Zn

V V + += =

Trong khi Zn givai tr ca mt anot, boxi ha theo phn ng

2 2Zn Zn e+ +

Ngc li phn ng : 2 2Fe Fe e+ + skhng xy ra.


- 18 -

CHNG II. NHNG NI DUNG IN HA HC TRONGCHNG TRNH HA HC PHTHNG.

II.1. Phn tch s hnh thnh v pht trin khi nim in ha hc trong

chng trnh ha hc trng THPT.

Khi nim in ha hc c xy dng trn nn tng ca kh nhiu l thuyt. Tuy

nhin mc phthng ngi ta cha ra mt sl thuyt lin quan nh: Thuyt

in li, Phn ng oxi ha kh L thuyt in ha hc c dng nghin cu cc

tnh cht ca cc cht, gii thch v tin on vtnh cht ha hc v tnh cht vt l.

Qu trnh pht trin khi nim in ha hc chng trnh phthng c thchia thnh

cc bc nhsau:

Bc 1: Lp 10: Hc sinh c hc vl thuyt phn ng oxi ha kh Phn ng oxi

ha kh l phn ng trong c s chuyn electron gia cc cht phn ng. Vn

dng l thuyt ny gii thch sxut hin dng in trong pin in ha, v qu trnh

trao i electron trong phn ng.

Bc 2. Lp 11: Pht trin khi nim in ha hc

Hc sinh c hc vthuyt in li: Tnh dn in ca cc dung dch axit bazvmui l do trong dung dch ca chng c cc tiu phn mang in tch, chuyn ng t

do c gi l cc ion hay Qu trnh phn li cc cht trong nc ra ion l sin li.

Nhng cht tan trong nc phn li ra ion c gi l cht in li

Vn dng l thuyt ny gii thch sxut hin thtrn cc in cc, schnh lch

thgia cc in cc t xut hin dng in di chuyn trong dy dn ni hai in

cc.

Bc 3. Lp 12: Pht trin v hon thin khi nim in ha hc.Tcc phn ng ha hc c trng ca kim loi trong chng i Cng Kim Loi

nh: Fe + HCl FeCl2+ H2

CuFeSOlCuSOFe ++ 44 )(


- 19 -

Da vo phn ng kim loi chuyn chcho nhau (kim loi ny c thy ion kim loi

khc ra khi mui ca chng) ngi ta xp xp c nhiu kim loi theo khnng

phn ng ca chngV d: ++ ++ 222 CuAgAgCu

Tuy nhin phng php trn cha tng qut v khng chnh xc. nh gi nh

lng khnng oxi ha khca cc kim loi, ion kim loi trong dung dch, ngi ta p

dng l thuyt ca in ha hc chng minh. Da vo i lng thoxi ha kh

(hay thin cc) ca chng ( 0M

Mn+ ).Tgi trthkhchun ngi ta c thso snh

c mnh yu ca cc kim loi v ion kim trong dung dch.V vy ngi ta xpxp c dy in ha sau:

+K +Na +2Mg +3Al +2Zn +2Fe +2Ni +2Sn +2Pb +H +2Cu +Ag +Au

K Na Mg Al Zn Fe Ni Sn Pb 2H Cu Ag Au

II.2. Cu trc ni dung in ha hc trong chng trnh ha hc phthnglp12, ban cbn, ban nng cao

Ha hc lp 12 nng cao Ha hc lp 12 cbn

Khi nim in ha hc, tp trung chyu chng 5:i cng vkim loi.

Bi 20 Dy in ha ca kim loi1. Khi nim cp oxi ha

kh2. Pin in (sut in ng,thin cc)

3. Thin cc chun (incc hiro chun,thincc ca cc kim loi)

4. Dy thin cc ca

Bi 18 Tnh cht ca kim loi dy inha ca kim loi.

1. Dy in ha ca kimloi.

Tnh oxi ha ca ion kim loi tng

Tnh khkim loi gim


- 20 -

kim loi.5. ngha ca thin cc.

Bi 21 Luyn tp: Tnh Cht Ca kim

loi

Bi 19 Hp kim

1. Khi nim2. Tnh cht3. ng dng

Bi 22 Sin phn.1. Khi nim.2. S in phn cc cht

in li2.1. in phn cht in li

nng chy2.2. in phn dung dch

cht in li trongnc.3. ng dng ca s inphn

Bi 20 Sn mn kim loi1. Khi nim2. Cc dng n mn3. Chng n mn kim loi3.1. Phng php bo v

bmt3.2. Phng php in

ha

Bi 23 Sn mn kim loi1. Khi nim.2. Hai dng n mn kim

loi2.1. n mn ha hc2.2. n mn in ha3. Chng n mn kim loi.

Bi 21 iu chkim loi1. Nguyn tc.2. Phng php.2.1. Phng php nhit

luyn2.2. Phng php thy

luyn2.3. Phng php inphn

Bi 24 iu chkim loi.1. Nguyn tc iu ch.2. Phng php iu2.1. Phng php thy

luyn2.2. Phng php nhit

luyn

2.3.

Ph

ng php

inphn

3. nh lut faraday

Bi 22 Luyn tp: Tnh cht ca kimloi

Bi 25 Luyn tp: Sin phn snmn kim loi iu ch kimloi

Bi 23 Luyn tp: iu ch kim loiv sn mn kim loi.


- 21 -

Bi 26 Bi thc hnh s 3. Dy inha ca kim loi iu chkim loi

Bi 24 Thc hnh: Tnh cht, iu chkim loi, sn mn kim loi.

Bi 27 Bi thc hnh s 4: n mnkim loi v chng n mn kimloi.

II.3. Mt skin thc cbn hc sinh cn nm vng khi hc vphn in

ha hc trng Trung Hc PhThng.

Ha hc lp 12 nng cao Ha hc lp 12 cbn

Bi 20 Dy in ha ca kim loi

Mt skin thc trng tm hc

sinh cn nm vng:

1. Hc sinh phi bit c khi

nin cp oxi ha kh, pin in

ha, sut in ng v thin

cc l g?

2. Hc sinh phi bit c cu

to ca pin in ha, schuyn

ng ca cc phn t mang

in khi pin in ha hot

ng?

3. Cc phn ng ha hc noxy ra cc in cc ca pin

in ha?

4.Bit c thin cc chun

Bi 18 Tnh cht ca kim loi dy

in ha ca kim loi.

Phn kin thc c s hc sinh

phi nm vng.

1. Thno l cp oxi ha kh?

V d: CuCuAgAg ++ 2

;

2. Thno l dy in ha ca

kim loi?

l dy sp xp cc cp oxi

ha kh theo chiu tng dn

tnh oxi ha ca ion kim loi v

gim dn ca tnh khkim loi

3. ngha ca dy in ha hc

l g?

Don chiu ca phn ng

gia hai cp oxi ha kh theo


- 22 -

l g? Chiu ca phn ng oxi

ha kh , tnh th in cc

chun ca cp oxi ha khtrong pin in ha?

5.Dy thin cc chun ca

kim loi v ngha ca n?

quy tc

CuCu

FeFe

++ 22

( ) ( ) ( ) ( )raqraq CuFeFeCu ++ ++ 22

Bi 22 Sin phn.

1. Hc sinh phi bit c s

in phn l g?

2. Bit nhng ng dng ca s

in phn trong cng nghip l

g?

3. Hiu schuyn dch ca cc

ion trong qu trnh in phn:

Mui NaCl nng chy, dung

dch CuSO4vi in cc trv

in cc tan (anot tan).

4. Hiu nhng phn ng ha

hc xy ra trn cc in cc

trong qu trnh in phn v

vit c phng trnh in

phn

Khng tch thnh bi ring

Bi 23 Sn mn kim loi

1. Hiu cc khi nim th no

l n mn kim loi, n mn ha

hc v n mn in ha hc?

2. Hc sinh phi bit c cc

Bi 20 Sn mn kim loi

1. Hc sinh phi bit c n

mn kim loi l g?

2. Hc sinh phi bit c c

cc dng n mn no trong t


- 23 -

iu kin v bn cht ca n

mn ha hc v n mn in

ha hc.3.Hiu c nguyn tc v cc

bin php chng n mn in

ha hc?

nhin?

3. Hc sinh phi bit cch

chng n mn kim loi l g?

Bi 24 iu chkim loi.

Phn kin thc trng tm.

1. Hc sinh phi bit c

nguyn tc chung iu ch

kim loi l g?

2. Hiu cc phng php c

vn dng iu chkim loi.

Mi phng php thch hp

vi siu chnhng kim loi

no. Dn ra c nhng phn

ng ha hc v iu kin ca

phn ng u ch nhng kim

loi cth.

Bi 21 iu chkim loi

Kin thc trng tm hc sinh

cn nm bt c l:

1. Nguyn tc iu chkim loi

l g?

Nguyn tc iu ch kim loi

l kh ion kim loi thnh kim

loi nguyn t

Mn++ ne M

2. Cc phng php iu ch

kim loi l g?


- 24 -

II. 4 . Mt svn gio vin cn ch khi dy phn in ha hc trng

THPT

II.4.1. Ni dung kin thc vin ha hc cc lp cbn, nng caoII.4.1.1. Lp 12 cbn

1. Bi 18: Tnh cht ca kim loi. Dy in ha kim loi

a/Dy in ha ca kim loi.

Nm tht chc vkhi nim cp oxh khca kim loi: Dng oxi ha v dng kh

ca cng mt kim loi to thnh cp oxi ha khca kim loi.

- lm rvn ny cn so snh mc hot ng ca cp oxi ha khkhng

nh u trnh bi:2Zn

Zn+

v2Cu

Cu+

T ta suy ra: 2 2Zn Cu Zn Cu+ ++ +

- Lin hcc phn ng gia kim loi v dung dch mui (da vo th), so snh c

khnng hot ng ca cc kim loi, sau trnh bi dy in ha

b/ ngha dy in ha kim loi .

Lm rquy tc xt chiu ca phn ng oxh - kh

2 2Cu Fe Fe Cu+ ++ +

Cht oxi ha mnh cht khmnh cht oxh yu hn cht khyu hn

2. Bi 20. n mn kim loi. Cc vn cn lu .

- Cn lm cho hc sinh thy rskhc nhau gia hin tng n mn ha hc v n

mn in ha hc. Sn mn in ha hc xy ra phbin hn trong thc tso vi n

mn ha hc.

- Vn dng nhng hiu bit vpin in lm rsn mn in ha hc- Tm hiu iu kin xy ra n mn in ha hc

3. Bi 21. iu chkim loi. Nhng vn gio vin cn lu :

- Cn lm rmi quan hgia mt hot ng ha hc ca cc kim loi v phng

php iu chda vo dy in ho.


- 25 -

- Nguyn tc iu chkim loi : Khion kim loi: nM ne M+ +

II.4.1.2. Lp 12 nng cao.

Cc vn gio vin cn ch y c lit k trong tng bi cth.

1. Bi 20: Dy in ha ca kim loi.

a/ Khi nim cp oxi ha khca kim loi.

Tm hiu khi nim v khi qut theo s. nM ne M+ +

Dng oxh Dng kh

b/ Pin in ha.

Cn cho hc sinh c nhng bc nhn thc nhsau:

- Quan st th nghim (th nghim hnh 5.3 SGK) pin in ha Zn Cu

- Gii thch cc hin tng quan st c trong qu trnh hot ng ca pin in ha

Zn Cu v vit phng trnh ha hc xy ra.

c/ Thin cc chun ca kim loi. Dy thin cc chun ca kim loi

Cn c nhng bc hot ng sau.

- Thng bo vthin cc hiro tiu chun.

+ Quy c vthin cc hiro chun: ( )20

2 0,00H H V + =

- Tm hiu cch xc nh thin cc chun ca kim loi. V dca Zn.

+ Nhng phn ng ha hc xy ra in cc khi pin Zn H hot ng

+ Lm rtrng hp no th thin cc chun ca cpnM

M+

c gi trdng, m.

- Da vo thin cc chun nu nguyn tc sp xp cc cp oxi ha khca kim

loi trong dy in ha hc.

d/ ngha ca dy thin cc chun ca kim loi.

Hot ng tm hiu v ngha ca thin cc chun ca kim loi, nn chia thnh

nhng hot ng nhsau:

- Hot ng tm hiu vchiu ca phn ng gia hai cp oxi ha khca kim loi.


- 26 -

- Phn tch phn ng gia hai cp oxi ha kh.

2 0( 0,34 )Cu VCu +

= + v 0( 0,80 )Ag VAg +

= +

Kt lun vchiu ca phn ng ha hc: C ba kt lun tng ng vmt ngha:

- Kim loi c cp oxi ha khc thin cc chun nhkhc kim loi ca cp

oxi ha khc thin cc chun ln hn trong dung dch mui.

- Cation kim loi trong cp oxi ha khc thin cc ln hn oxi ha c kim

loi trong cp oxi ha khc thin cc nhhn.

- Cht oxi ha mnh hn soxi ha cht khmnh hn, sinh ra cht oxi ha yu hn

v cht khyu hn. (quy tc )2. Bi 22. Sin phn. Cc vn cn ch khi dy bi 22.

a/ Khi nim vsin phn.

- Lin hn thca cc cp oxi ha khxc nh: Tn cc in cc, du ca cc

in cc v phn ng xy ra cc in cc.

b/in phn dung dch CuSO4vi in cc graphit. dung dch CuSO4vi Anot tan

Cn lm rthtin phn ca cc ion, phn tcc in cc da vo dy thin

cc.

3. Bi 23.Sn mn kim loi. Cc vn cn lu khi dy bi 23.

- Cn lm rnguyn nhn no dn n n mn in ha, lin hli bi dy in ha.

- iu kin xy ra sn mn ha hc?

4. Bi 24: iu chkim loi. Cc vn cn lu .

a/ Phng php thy luyn.

- Csca vic iu chkim loi bng phng php thy luyn- Phng php thy luyn c dng iu chnhng kim loi no

b/ Phng php in phn.

- Csca phng php in phn iu chkim loi. Nhng kim loi no c thiu chc bng phng php in, lin hdy in ha.


- 27 -

II.4.2. Phng php dy hc vcc vn in ha hc

Nhm t c kt qu tt nht v vic hc sinh c thhiu, nm vng cc kin

thc cbn vin ha hc th i hi khng chngi gio vin nm vng vnidung kin thc m cn phi c phng php sphm kho lo. Phng php ng vai

tr kh quan trng trong qu trnh hc sinh tip thu kin thc. Mt sphng php dy

hc ha hc chung c ththp dng cho phn in ha hc nh:

- Sdng thit bth nghim, m hnh ha hc theo nh hng chyu l ngun

hc sinh nghin cu, khai thc tm ti kin thc ha hc.

- S cu hi v bi tp ha hc hc sinh chng nhn kin thc, hnh thnh k

nng v vn dng tch cc cc kin thc, knng hc.

- Ty vo tnh cht ca cc bi hc trong chng, ta c thphn chia thnh hai phng

php hnh thnh kin thc cho hc sinh nhsau.

+ i vi loi bi hc nhm xy dng v hnh thnh khi nim mi cho hc sinh, nh

bi: Dy in ha ca kim loi, in phn, Sn mn kim loi,phng php dy

nn thit ktheo m hnh dy nhsau:

+ i vi nhng loi bi hc i hi svn dng l thuyt tm hiu tnh cht ca

cht, nhtm hiu tnh cht vt l, tnh cht ha hc chung ca kim loi, iu chkim

loi,.th phng php dy hc nn thit ktheo m hnh sau:

Th nghim nghincu, quan st cchin tng thnghim.

Vn dng l thuytcho gii thchcc hin tng quanst c

Kt lun hoc hnhthnh khi nim

mi

Vn dng l thuytcho bit

Don cu to vtnh cht ca cht

Khng nh nhngiu don bng

thn him.


- 28 -

II.5. Vn dng mt skin thc vin ha hc ging dy ni

dung in ha hc trong chng trnh ha hc trng THPT

II.5.1. Sdng Thin Cc tnh Sc in ng v don xem mt phn

ng oxi ha khcho trc c khnng xy ra hay khng.

Csl da vo biu thc: G nFE = . 250C th ta c: 0 0G nFE =

Trong : n- s electron trao i. F- hng sFaraday. E0 sut in ng ca phn

ng.

- Nu 0 0 0E G> < Phn ng tdin bin.

- Nu0

0 0E G< > Phn ng xy ra theo chiu nghch.- Nu 0 0 0E G= = Phn ng t cn bng.

V d: Tnh sut in ng v don xem phn ng sau c xy ra khng 250C?

( ) ( ) ( ) ( )2 2aq r r aqCd Cu Cd Cu+ ++ + ; bit 2 2

0 00,40 ; 0,34Cd Cu

Cd Cu

V V + += =

Ta c:

( )

( ) ( ) ( ) ( )

2

2

2 0

2 0

2 2 0

2 ; 0,40

2 ; 0,34

; 0,74

aq CdCd

CuCu

aq r r aq

Cd e Cd V

Cu Cu e V

Cd Cu Cd Cu E V

+

+

+

+

+ +

+ =

+ =

+ + =

Vy sut in ng 0 0,76 0 0pinE V G= < > phn ng khng c khnng xy

ra theo chiu nhtrn.

II.5.2. Tnh thca mt bn phn ng khi bn phn ng l thp ca hai hay

nhiu bn phn ng khc.

Tnh thca bn phn ng: ( ) ( ) ?,303

3 =++ raq TleTl bit:

( )+3

aqTl ( )+

aqTl Tl

03 ? =

V336,002 = V250,101 =


- 29 -

p dng biu thc :21

022

0110

3 nn

nn

+

+=

. Ta c :

( ) ( )

( )

( ) ( ) VTleTl

VTleTl

VTleTl

raq

aq

raq

?,3

250,1,2

336,0,

0

3

3

02

3

01

=+

=+

=+

+

++

+

Trong : n1; n2; l selectron trao i trong bn phn ng (2),(3).

02

01 ; l thchun ca bn phn ng (2), (3).

Khi ta c:( ) ( )

Vnn

nn721,0

3

250,12336,01

21

022

0110

3 =+

=+

+=

Vy thca bn phn ng: ( ) ( ) VTleTl raq 721,0,303

3 =++

II.5.3. Don bn ca cc trng thi oxi ha ca mt nguyn t.

Xt bn phn ng: ( ) ( ) ( )++ + 323 aqraq AuAuAu bit:

( )3aqAu

+ ( )aqAu+ Au

Nu Au+ t oxi ha kh th phng trnh phn ng trn c th 00 >puE , v khi

00 00puE 00


- 30 -

II.5.4.1. Don c chiu xy ra ca phn ng.

Phn ng oxi ha khlun xy ra theo chiu to ra cht oxi ha v cht khyu hn,

ngha l cht oxi ha mnh nht soxi ha cht khmnh nht.Bi tp vn dng.

Bi tp 1. a/ Hy cho bit vtr ca cp MnMn +2 trong dy in ha. Bit rng H+oxi

ha c Mn. Vit phng trnh ion thu gn.

b/ C thdon iu g xy ra khi nhng l kim loi Mn vo cc dung dch mui:

AgNO3,MnSO4, CuSO4? Hy vit phn ng di dng phng trnh ion rt gn nu c

Li gii.

a/ H+oxi ha c Mn, ngha l Mn c khnng khc H+:

++ ++ 222 HMnHMn

2MnMn

+

xp trc2

2H

H+ trong dy in ha.

b/ Trong dy in ha ta c: Mn xp trc Cu , Ag Mn c tnh khmnh hn. V

thxy ra c cc phn ng:

++ ++ CuMnCuMn 22 ( Cu bm trn l Mn)

++ ++ AgMnAgMn 22 ( Ag bm trn l Mn)

II.5.4.2. Xc nh tn kim loi.

1.c cng thc tng qut hp cht cha kim loi l:

( ( ) ( ) ( )2 4 3 2 3, , , , .....x y n m a bM O RCl A SO B NO X CO ) sau tm khi lng nguyn t

ca kim loi (M,R, A, B, X,) ri suy ra kim loi .Thng gp hai trng hp:

- Trng hp 1:Bit ha trkim loi cn tm, da vo dkin bi tp lp phng

trnh ton hc, tm khi lng nguyn tca kim loi, suy ra tn kim loi .

- Trng hp 2:Khng bit ha trkim loi cn tm, da vo dkin bi lp biu

thc lin hgia nguyn tkhi (M) ca kim loi vi ha tr(n) ca kim loi .

Sau , bin lun M theo n (hay ngc li), tm cp nghim M, n hp l, suy ra tn kim

loi.


- 31 -

2. Bi tp vn dng. Nhng mt thanh kim loi M vo dung dch NiSO4sau mt thi

gian thy khi lng thanh kim loi gm 0,12g. Xc nh tn kim loi M. Bit M ha

trII v smol NiSO4hao ht 0,02mol. Tnh sgam kim loi tham gia phn ng.Li gii

Phn ng: ( )4 4iSO 1M N MSO Ni+ +

mol 0,02 0,02 0,02 0,02

Theo bi, ta c:0,12

0,02 65 :59

MM

= =

km (Zn)

Vy : mZn tham gia phn ng= 65

II.5.4.3. Tng gim khi lng thanh kim loi

Nhng mt thanh kim loi A v dung dch mui ca kim loi B (cha ion Bn+). Sau

mt thi gian ly thanh kim loi ra, ra nh, sy kh, cn th thy khi lng thanh kim

loi c thtng hoc gim.

1. Khi lng thanh kim loi tng: Th ta p dng phng trnh i ssau.

2. Khi lng thnh kim loi gim: Th ta p dng phng trnh i ssau:

3. Bi tp vn dng:Thanh km nng 5,2 gam c cho vo 100ml dung dch

CuSO41M, sau mt thi gian, ly thanh km ra cn c 5,18 gam.Tnh khi lng Cu

bm vo thanh Zn.

Ta c: molndaubanCuSO

1,011,04

==

Phn ng:aaaamol

CuZnSOCuSOZn ++ 44

Ta c: 65a 64a = 5,2 - 5,18 a = 0,02 mol

Khi lng thanh Cu = 0,02 . 64 = 1,28 gam

Mkim loi tng = m kim loi gii phng- mkim loi tan

Mkim loi gim = mkim loi tan- m kim loi gii phng


- 32 -

II.5.5. Kim loi lin quan n sin phn.

Dng 1:in phn dung dch cc mui, Axit, baz

- Catot: Nu cation ( ++ HMn ; ) ng sau Al3+trong dy in ha ca kim loi, skh

cho ra kim loi hoc H2.

Nu cation l Al3+hoc mt kim loi ng trc Al trong dy in ha ca kim loi

( ....;; 2+++ BaNaK ) th nc sbkhcho ra H2v ion OH

++ OHHeOH 22 22

- Anot: Nu ion l X (X l halogen nhCl, Br, I.) hoc OH-th soxi ha cho ra

X2hoc O2: 2 2 212 2 2 22Cl Cl e hay OH O H O e + + +

Nu anion l ....;; 24243

POSONO th lc ny nc sboxi ha cho ra O2v H+

eHOOH 222

122 ++

+

Dng 2: Trng hp c nhiu cation c thbkhbn catot

Cc cation ion bkhtheo thttnh oxi ha gim dn, ion bn phi (c tnh oxi ha

mnh nht) bkhtrc ri n ion bn tri trong dy in ha ca kim loi.Dng 3: Trng hp c nhiu anion boxi ha bn anot:

Cht c tnh khmnh nht sboxi ha trc.

Dng 4: Dng cng thc Faraday tnh khi lng cc cht thot ra cc in cc:

n

AItm

96500=

Bi tp vn dng:in phn c mng ngn in cc tr 100ml dung dch MgCl2

0,5M vi cng dng in I = 0,1A vi thi gian 9650s. Tnh nng mol/l dungdch mui sau phn ng.

Ta c: molnMgCl 015,015,01,02 ==

2 2

2 0.1 9650 0,010,01 0,005

96500 2 96500 2H HAIt

m g n moln

= = = = =


- 33 -

Phn ng:005,0005,0

)()(2 22222mol

dpddHClOHMgOHMgCl +++

Smol MgCl2d= 0,015 0,005 = 0,01mol ; Vy: MC MgClM 1,01,001,0)( 2 ==

II.5.6. Kim loi phn ng vi dung dch mui.

Dng 1:Mt kim loi y mt ion kim loi khc.

iu kin kim loi X y kim loi Y ra khi dung dch mui ca Y

- X phi ng trc Y trong dy in ha.

- Mui ca kim loi Y phi tan trong nc.

Dng 2:Cho mt kim loi X vo dung dch cha hai mui ca hai kim loi Yn+

, v Zm+

.- n gin trong tnh ton, ta chxt trng hp X ng trc Y v Z, ngha l kh

c chai ion Yn+, v Zm+(Y ng trc Z)

- Do Zm+c tnh oxi ha mnh hn Yn+nn X phn ng vi Zm+trc:

++ ++ qZmXqZmX qm (1) q l ha trca X.

Nu sau phn ng (1) cn dX th c phn ng: ++ ++ qYnXqYnX qn (2)

Vy, cc trng hp xy ra sau khi phn ng kt thc:

+ Nu dung dch cha 3 ion kim loi (Xq+;Yn+; Zm+) th khng c phn ng (2) xy ra,

tc l kim loi X ht v ion Zm+cn d:

+ Nu dung dch cha hai ion kim loi (Xq+;Yn+) th phn ng (1) xy ra xong (tc ht

Zm+), phn ng (2) xy ra cha xong (dYn+) tc X ht.

Bi tp p dng: Cho 0,387 gam hn hp (A) gm Zn v Cu vo dung dch c cha

0,005 mol Ag2SO4, khuy iu, ti phn ng hon ton thu c 1,144gam cht rn.

Tnh khi lng mi kim loi.

Li gii

Phn ng:+=+

+=+

AgCuSOSOAgCu

AgZnSOSOAgZn

2

2

442

442

- V tng smol Zn v Cu nm trong gii hn.


- 34 -

0,387 0,3870,0059 0,00604

65 64hh hhn n< < < <

hhn l

n h

n 0,005mol, ch

ng t

Ag2SO4h

t.

- GisZn phn ng mt phn, Cu cha tham gia phn ng.Gi smol Zn ban u l

x, smol Zn phn ng l x. Gi smol Cu ban u l y. Khi lng thanh kim

loi tng.

108.2x 65.x= 1,144 0,387 = 0,757 (g) 151x= 0,757 x = 0,00501

Smol ny lhn 0,005mol, iu ny khng ph hp vi bi, do Zn phn ng

ht v x = x.

- Zn phn ng ht, Cu tham gia phn ng mt phn.Gi smol Cu tham gia phn ngl y. Ta c phng trnh khi lng kim loi tng

108.2x 65x + 108.2y 64.y = 0,757 (1). Gii phng trnh (1) kt hp vi phng

trnh: x + y = 0,005 .Ta c:

=

=

002,0

003,0

y

x : Vy mZn= 0,003. 65 = 0,195 (gam)

mCu= 0,387 0,195 = 0,192 (gam)

II.5.7. Kim loi tc dng vi dung dch axit.

II.5.7.1.Tc nhn oxi ha l ion H+trong axit.

Cc axit HCl, H2SO4long,anion gc axit ca chng khng c tnh oxi ha.

)1(2 2 ++ ++ HnMnHM n

Ch : Phn ng (1) xy ra khi kim loi M ng trc hiro trong dy hot ng ha

hc ca kim loi.

II.5.7.2. Tc nhn oxi ha l anion gc axit.

Anion ca cc axit (HNO3, H2SO4(c, nng)) oxi ha kim loi chkhng phi H+l tcnhn oxi ha nn kh to thnh khng phi l kh hiro, m l sn phm khca anion.

- H2SO4(c, nng)c thbkhcho ra: SO2, S, H2S- HNO3c thbkhcho ra : NO2, NO, N2, N2O, NH4NO3


- 35 -

II.5.7.3. Bi tp vn dng.

Bi tp: Ha tan 62,1gam kim loi M trong HNO3long, cho 16,8 lt hn hp kh X

(ktc) gm hai kh khng mu, khng ha nu ngoi khng kh. C t khi hi so vikhi H2 l 17,2. Xc nh tn M? Tnh thtch dung dch HNO32M, bit axit dng d

25% so vi lng cn thit.

Li gii

Hai kh khng mu do HNO3long sinh ra l N2v N2O.

Gi x,y ln lc l smol ca N2v N2O. Theo bi ta c:

==+

==

+

+

75,04,228,16

4,3422,174428

yxyx

yx

=+=+75,0

8,254428yx

yx

==

3,045,0

yx

Phn ng: 10M + 12xHNO3 = 10M(NO3)x + xN2 + 6xH2O

Mol 4,5/x 5,4 0,45

8M + 10xHNO3 = 8M(NO3)x + xN2O + 5xH2O

Mol 2,4/x 3 0,3

x

x

M 9691,62 == nghim hp l l: x = 3, M = 27: Nhm (Al)

Smol HNO3dng d: 8,4 .25% = 2,1mol

tng smol HNO3: 8,4 +2,1 = 10,5 mol

Vy thtch dung dch HNO3= )(25,52

5,10l=


- 36 -

CHNG III. MT SKT QUBAN U

III.1.Thc trng nm vng khi nim in Ha Hc trng TrungHc PhThngIII.1.1. iu Tra Thc Trng

Chng ti tin hnh iu tra 1 khi lp gm 2 lp 12 nng cao 12A1 ,12A3v 2

lp 12 ban cbn gm 12C1 ,12C2. trng THPT Lai Vung II.

III.1.1.1. Mc ch.

nh gi cht lng nm kin thc in ha hc ca hc sinh phthng khi lp 12.

III.1.1.2. Tin Hnh.1. Lp 12 nng cao.

Chng ti pht phiu iu tra xem xt tnh hnh nm kin thc phn in ha hc

ca hc sinh cc lp 12A1 ,12A3trng THPT Lai Vung II.

Slng phiu pht ra: 87 phiu, thu v87 phiu, phiu gm 10 cu hi trc nghim,

mi cu c nhiu kin la chn.

a. Kt Qu.

Sau khi thng k sliu, kt quthu c nhsau.( Xem phlc 2)

Ngoi xl kt qutng cu mt, chng ti cn cho im tng bi mt.Cch cho im

nhsau: Bi gm 10 cu hi trc nghim 10 im. Mi cu ng c 1 im.

Sau y l kt qutng lp.

Xi 0 1 2 3 4 5 6 7 8 9 10

fXi 0 0 2 0 1 2 3 8 15 9 212A1

% 0 0 4,76 0 2,4 4,76 7,14 19,05 35,7 21,43 4,76

fXi 0 0 0 0 1 3 8 10 11 10 212A3

% 0 0 0 0 2,22 6,67 17,78 22,22 24,44 22,22 4,45


- 37 -

Trong : Xil im s.

fXil sln xut hin ca im s.

Bi u th hin tlhc sinh t cc mc i m t1 - 10 ca hc sinh hai lp 12A1 v 12A3

0

10

20

30

40

0 1 2 3 4 5 6 7 8 9 10 im

%

Tl% hc sinh t imlp 12A1

Tl% hc sinh t imlp 12A3

Hnh III.1. Biu din tlhc sinh t im ca hai lp 12A1 v 12A3Sau khi thng k kt qu, tlxp loi nhsau:

- Loi yu : (0 4) : 4,59%- Loi trung bnh : (5 6) : 18,39%- Loi kh : (78) : 50,57%- Loi gii : (9 10) : 26,45%

Biu din cc kt qudi dng biu .

Bi u th hin tlx p loi hc lc ca hai lp12A1 v 12A3

4.59

18.39

50.57

26.45

Loi yu

Trung bnh

Loi kh

Loi gii

Hnh III.2.Tlxp loi hc lc ca hai lp 12A1 v 12A3b. Nhn xt

Sau khi chm im tng cu, tng bi v thng k cc sliu, chng ti nhn thy a

shc sinh lp 12 ban nng cao nm c mt skin thc cbn vvn in ha

hc. Tuy nhin phn ln cc em cha nm su kin thc. T lhc sinh loi gii ch


- 38 -

chim 26,44%. Bn cnh vn cn mt shc sinh mt cn bn vphn kin thc

ny. Tlhc sinh loi yu chim 9,84%

Qua thng thng k kt qutng cu hi chng ti rt ra nhng nhn xt sau :- Hc sinh tr li kh tt cc cu 1(93,1%) ; cu 2 (88,5%); cu 5 (93,1%); cu 7

(77%); cu 9 (91,95%); cu 10 (94,25%) l cc cu hi lin quan n phn ng oxi ha

kh, dy hot ng ha hc ca kim loi, thca pin.Tuy nhin vn cn mt shc

sinh cha nm vng kin thc cbn ny, shc sinh tr li sai cc cu 7, cu 9 t

(10% - 20%).

- Cc cu 4, cu 6, cu 8, hc sinh ch tr li c mc trn trung bnh (50% -

70%). Nhvy vn cn trn 30% hc sinh trli sai, do cc em cha nm vng kin

thc vin phn, n mn kim loi v thca pin.

- Khi vn dng l thuyt in ha vo vic gii cc bi tp tp th a shc sinh lm

kh tt, tuy nhin mt st hc sinh vn cn tra lng tng.

2. Lp 12 Ban CBn.

Chng ti cng pht phiu iu tra kin thc vin ha hc dnh ring cho hc

sinh lp 12 ban cbn. Phiu iu tra c pht cho 2 lp 12C1v 12C2. trng THPT

Lai Vung II.

Slng phiu pht ra l: 78 phiu, thu v78 phiu, gm 10 cu hi trc nghim, mi

cu c nhiu kin la chn.

a. Kt qu.

Sau khi thng k sliu kt qunhsau . (Xem phlc 3)

Ngoi xl kt qutng cu mt, chng ti cn cho im tng bi mt, cch cho im

nhsau: Bi 10 cu hi trc nghim 10 im. Mi cu ng c 1 im. Sau y

l kt qutng lp:


- 39 -

Xi 0 1 2 3 4 5 6 7 8 9 10

fXi 0 0 5 5 6 8 9 4 212C1

% 0 0 12,82 12,82 15,38 20,51 23,08 10,26 5,13fXi 0 0 0 6 11 13 4 2 1 212C2

% 0 0 0 15,38 28,21 33,33 10,26 5,13 2,56 5,13

Trong : Xil im s.

fXil sln xut hin ca im s.

Biu din cc kt qudi dng biu .

Hnh III.3.Biu din tlhc sinh t im ca hai lp 12C1 v 12C2Sau khi thng k kt qu, tlxp loi nhsau :

- Loi yu : (0 4) : 42,31%- Loi trung bnh : (5 6) : 43,59%- Loi kh : (78) : 11,54%- Loi gii : (9 10) : 2,56%

Biu din cc kt qudi dng biu


- 40 -

Bi u th hin tlx p loi hc lc ca hai lp12C1 v 12C2

42.31

43.59

11.54 2.56

Loi yu

Trung bnh

Loi kh

Loi gii

Hnh III.4.Tlxp loi hc lc ca hai lp 12C1 v 12C2

b. Nhn Xt.

Sau khi x l tng tnh lp 12 ban nng cao chng ti nhn thy hc sinh lp 12ban cbn ca trng nm kin thc vin ha hc cha vng, tlhc sinh loi yu

chim ti 43,31%, cn tlhc sinh t loi kh 11,54%, gii 2,56%.

- Cc cu hc sinh tr li tng i tt l Cu 1(87,18%), Cu 2 (83,33%), Cu 4

(50%), Cu 6 (73,08%), Cu 8 (52,56%) l nhng cu c lin quan n cc vn nh:

Phn ng oxi ha kh, dy in ha, n mn kim loi, iu l nhng phn kin thc

cc em va hc.

- a shc sinh trli cha tt cc cu 3 (33,33%), cu 5(2,56%), cu 7(20,51%), cu

9 (20,51%), cu 10 (15,54%) l cc cu c lin quan n cc dng ton p dng phn

in ha hc nh: in phn, dy in ha, cc kin thc l thuyt vin phn....ng

thi qua kt quca cc cu ny chng ti nhn thy a shc sinh cha nm vng

bn cht ca kin thc in ha hc, cc em chnm c mt cch ssi v chbit

p dng vi nhng dng bi tp quen thuc cn nhng bi c tnh nh hu nhcc

em u khng lm c.


- 41 -

III.1.2. Nhn xt, nguyn nhn v gii php.

III.1.2.1. Nhn xt chung.

- a shc sinh phn no nm c nhng kin thc cbn vin ha hc. Tuynhin, phn ln cc em cha nm tht chc v su kin thc, cc em thng ch ch

hiu bit vn mt cch ssi.

- a scc em chtrli ng nhng vn lin quan n cc kin thc m cc em

gp thng xuyn.

lp 12 ban nng cao, hu ht hc sinh trli rt tt cc vn vdy in ha, phn

ng oxi ha - kh. lp 12 ban cbn l cc vn vdy in ha, phn ng oxi

ha kh.

- i vi nhng cu hi c lin quan n phn kin thc vin phn, n mn kim

loi, hay vn dng cc kin thc in ha vo gii cc bi tp nh lng, th a scc

hc sinh trli vi tlng rt thp, c bit l ban cbn. Do khi dy bi mi

gio vin cn phi ch thng xuyn n li nhng kin thc cc lin quan n bi

hc hc sinh khc su kin thc.

- lp 12 ban nng cao, vi chng trnh ci cch hin nay th kin thc in ha hc

c cp nht rt nhiu, a sl nhng vn mi do hc sinh tra lng tng khi

gp phn kin thc ny. V d nh: Pin in ha, sc in ng, thin cc, in

phn....bn cnh mt sgio vin chdy thong qua cha thkhc su c kin

thc.

- Chng ti nhn thy mc nm vng kin thc in ha hc c schnh lch gia

cc lp. c bit l ban cbn.

III.1.2. 2. Nguyn nhn v gii php.

1/ Nguyn nhn khch quan v nguyn nhn chquan.

- Nguyn nhn khch quan.

in ha hc l phn kin thc kh kh, mang tnh khi qut, tru tng nn hc sinh

hiu mt cch cha y , mt khc y l khi nim c manh nha hc cui nm


- 42 -

lp 9 bc THCS (dy hot ng ha hc ca kim loi ), v n phn cui ca lp 12 n

mi c trnh bi mt cch y , v vy hc sinh mt ln khng thhiu ht c.

- Nguyn nhn chquan.Khi dy vphn kin thc in ha hc a sgio vin thng cha ch n vic s

dng cc phng tin trc quan nh: m hnh, hnh v, m hnh ha cc kin thc

gip hc sinh dhiu, dnhv nhlu. ng thi phn ln gio vin cng cha ch

n vic phi hp, sdng linh hot cc phng php ging dy, cha thng xuyn

n tp, cng ckhc su kin thc cho hc sinh.

2/ Gii php.

- Trc ht gio vin phi nm tht chc kin thc chuyn mn. ng thi cng phi

sdng, phi hp linh hot cc phng php dy hc khc nhau nng cao hiu qu

ging dy, gip hc sinh hng th hc tp, khng bnhm chn khi phi hc mt s

lng ln kin thc nhhin nay.

- Gio vin phi cho hc sinh xem xt cc vn ca cc cht trn csvn dng kin

thc in ha hc gii quyt.

- Khi dy phn l thuyt cs in ha gio vin cn ch ging tht k, nhn mnh

phn trng tm v khc su cc kin thc. Cho hc sinh gii thch rmu cht ca vn

lm cslnh hi cc kin thc lin quan sau ny.

- Gio vin phi ch hnh thnh cho hc sinh cc kin thc hin i, va sc v ty

theo trnh ca mi hc sinh.

- Gio vin phi hng dn rn luyn cho hc sinh lm cc bi tp vvn lin quan

n kin thc in ha nh: Dy in ha, in Phn, n mn kim loi, Pin in ha.

- Trong qu trnh ging dy cc ban khc nhau gio vin cn ch trnh ca mi

hc sinh, kin thc in ha mi ban c trnh bi nhng mc khc nhau. T

iu chnh dy cho ph hp.


- 43 -

III.2. Thit kmt sgio n dy vphn in ha trng trung hc

phthng

Da trn tnh hnh cc trng phthng theo kt quiu tra, chng ti thit k

mt sgio n khi ging dy cc bi vin ha hc. son cc gio n ny ti

da trn dn bi sch gio khoa, cc sch tham kho, sch bi tp v cc ti liu c lin

quan, ng thi ti cng tham kho kin ca gio vin phthng, tham kho cc

gio n mu ca cc gio vin lu nm, nhiu kinh nghim.

GIO N HA HC 12 NNG CAOBI:DY IN HA CHUN CA KIM LOI

I. MC TIU BI HC:

1. Kin thc:

Bit :

Cc khi nim: cp oxi ha-khca kim loi, pin in ha, sut in ng v

thin cc. Cu to ca pin in ha, schuyn ng ca cc phn tmang in khi pin

in ha hot ng.

Cc phn ng ha hc xy ra catot v anot ca pin in ha.

Thin cc chun ca kim loi.

Hiu: Dy thin cc chun ca kim loi v ngha ca n.

2. Knng:

So snh tnh oxi ha ca cc ion kim loi, tnh khca cc kim loi gia cccp oxi ha kh.

Xc nh tn v du ca cc in cc trong pin in ha, tnh c sut in

ng ca pin in ha.


- 44 -

Tnh c thin cc chun ca mt scp oxi hakhtrong pin in ha

II. CHUN B:

Lp rp mt spin in ha ZnCu, PbCu, ZnPb theo hnh 5.3 SGK. Mt stranh nh c vtrc:

* S chuyn dch ca cc ion trong pin in ha ZnCu, hnh 5.6 SGK

* Scu to in cc hidro chun, hnh 5.7 SGK

* Th nghim xc nh thin cc chun ca cp Zn2+/Zn hnh 5.8 SGK.

* Th nghim xc nh thin cc chun ca cp Ag+/Ag, hnh 5.9 SGK

* Bng dy in ha chun ca kim loi (SGK). Tranh vmt spin in ha.

III. Hot ng:1.n nh lp:

2. Khoch ging dy : Tit 1: Phn I v II.

Tit 2:Phn III.

Tit 3:Phn IV v V.

HOT NG CA GV HOT NG CA HSI

. Khi nim vcp oxi ho khHot ng 1.

Cu hi 1: Hon thnh phng trnh

ho hc v vit squ trnh oxi

ho - khca phn ng:

a) Cu + AgNO3

b) Fe + CuSO4

* GV nu vn . C thbiu dincc qu trnh oxi ho khtheo cch

khc c khng?

Cp oxi ha khl mt cp gm

I

. Khi nim vcp oxi ho khHc sinh ghi chp

Hon thnh phng trnh ho hc.

a) Cu + 2AgNO3 Cu(NO3)2+ 2Ag

Cu Cu2++ 2e

Ag++ 1e Ag

b) Fe + CuSO4 FeSO4+ Cu

Fe Fe2+

+ 2eCu2++ 2e Cu

hoc vit gp : Fe2++ 2e Fe

Cu2++ 2e Cu


- 45 -

cht oxiha v mt cht khca

cng 1 nguyn tha hc

Cu hi 2: Xc nh cht oxi ho -kht rt ra nhn xt.

* GV a ra s tng qut v gii

thiu cp oxi ho - kh.

II. Pin in ho

Hot ng 2.1. Khi nim vpin in ha, sut

in ng v thin cc:

GV tin hnh th nghim nh SGK

hoc m tth nghim (sdng s

pin in ho Zn-Cu) hnh 5.3. Nu c

iu kin dng phn mm m phng

pin in ho cho HS xem.

2. Cchpht sinh dng in:

- M t cu to ca pin, hot ng

ca pin, nhn xt v gii thch?

* GV dng s hnh 5.4, 5.5, 5.6

hoc dng phn mm m phng cho

HS xem v yu cu HS nhn xt, gii

thch schuyn dch e in cc Zn,

Ag++ 1e Ag

Cht oxi ha cht kh

Tng qut : Mn+ + ne MDng oxi ha v dng kh ca cng mt

nguyn tto thnh cp oxi ha kh. Cc cp

oxi ha khtrn c vit nhsau:

Fe2+/Fe ; Cu2+/Cu ; Ag+/Ag.

Tng qut: Mn+/M

II. Pin in ho

1. Khi nim vpin in ha, sut inng v thin cc

Hc sinh quan st hin tng th nghim

+ Kim loi tan vo dung dch

+ Sut in ng ca pin ha hc

Epin= 1,10 V

+ Mu ca cc dung dch cha CuSO4?

/v pin in ha Zn/Cu hnh 5.3 ta c:

)/()/( 22 ZnZno

CuCuo

pino EEE ++ =

2. Cchpht sinh dng in

Gii thch.

* in cc Zn (cc m) l ngun cung cp e,

Zn boxi ho thnh Zn2+tan vo dung dch:

Zn Zn

2+

+ 2e* in cc Cu (cc dng) cc e n cc Cu,

y cc ion Cu2+bkhthnh kim loi Cu

bm trn bmt l ng.


- 46 -

in cc Cu, cu mui tri, cu mui

phi.

- Vit phng trnh ion rt gn.

* GV yu cu HS vit cc cp oxi

ho-kh

* GV gii thiu quy tc

(3) Nhn xt

- GV yu cu HS nhn xt nng

ca cc ion trong dung dch mui

CuSO4 v ZnSO4 s tng gim nh

th no trong qu trnh in phn ?

Sut in ng E ca pin in ho

phthuc vo yu tno?

Cu2++ 2e Cu

* Cu mui tri: Cation NH4+( hoc K+) di

chuyn sang cc ng dung dch CuSO4* Cu mui phi: Cc cation NO3

di chuyn

sang cc ng dung dch ZnSO4. Sdi

chuyn ca cc ion ny lm cho cc dung

dch mui lun trung ho in.

* Phng trnh ion rt gn biu din qu

trnh oxi ho-khxy ra trn bmt cc in

cc ca pin in ho:

Cu2+ + Zn Cu + Zn2+

Ox Kh Kh. yu Ox yu

Zn CuZn Cu

2+2+

3. Kt lun:

C s bin i nng cc ion Cu2+ v

Zn2+trong

qu trnh hot ng ca pin. Cu2+gim, Zn2+

tng

Nng lng ca phn ng oxi ha kh

trong pin in ha sinh ra dng in mt

chiu.


- 47 -

- GV yu cu HS cn c vo cc cp

pin cho trong SGK cho bit qu

trnh oxi ho kh din ra trong pinCu-Ag; Pb-Cu; Zn-Pb nhthno ?

III. Thin cc chun ca kim

loi

Hot ng 3 :

1. in cc hidro chun

- V sao cn phi xc nh thin

cc chun cho mi cp oxihakh?

- thng bo thin cc chun:

Dng hnh 5.7 xc nh

Cn phi xc nh thin cc cho

mi loi cp oxi ho- khv vy dng

in cc chun so snh l in

cc hiro chun.

Nhng yu t nh hng n sut in

ng ca pin in ha nh:

* Nhit .* Nng ca ion kim loi.

* bn cht ca kim loi lm in cc.

III. Thin cc chun ca kim loi

1. in cc hidro chun

HS xem hnh 5.7 v ghi

Ngi ta chp nhn mt cch quy c rng

thin cc ca in cc hidro chun bng

0,00V mi nhit

H2 2H+ + 2e

VE HHo 00,02/2 =+

HS tho lun theo nhm c i din trnh

by.

a. Cu to ca in cc hiro chun.

- in cc platin.

- in cc nhng vo dd axit H+1 M.

b. Cch xc nh thin cc chun hiro

chun.

- Cho dng kh H2c p =1 atm lin tc i qua

dd axit bt Pt hp thkh H2.

- Qui c thin cc hiro chun cp oxiho khH+/H2 l 0,00 V ; E

0 (H+/H2)= 0,00

V


- 48 -

2. Thin cc chun ca kim loi:

- HS dng hnh 5.8 trnh by nhng

ni dung ca th nghim xc nh thin cc chun ca cp Zn2+/Zn ?

- Cch lp thit b xc nh th

in cc chun ca Zn?

Nhng phn ng ha hc xy ra

cc in cc khi pin ZnH hot ng?

Th in cc chun ca cp

Zn2+/Zn l 0,76V

Thin cc chun ca kim loicn

o c c xc nh t bng sut

in ng ca pin to bi in cc

hidro chun v in cc chun ca

kim loi cn o.

Dng hnh 5.9 trnh by ni dung

th nghim xc nh th in cc

chun ca cp Ag+/Ag. Hot ng

dy v hc tng ttrn.

2. Thin cc chun ca kim loi

Cch xc nh thin cc chun ca kim

loi- Thit lp pin in ho gm: in cc chun

ca kim loi bn phi, in cc chun ca

hiro bn tri vn khiu sin thln

nht gia hai in cc chun. Nu in cc

kim loi l cc m E00.

* HS trli:

- Hiro l in cc (+): 2H++ 2e H2

- Km l in cc ( ) : Zn Zn2++2e

Zn + 2H Zn + H22++

2e

* Vn kchs0,76 V.

Cho bit hiu sin thln nht gia 2 in

cc chun ca cp Zn2+/Zn v H+/H2.

K hiu: E0(Zn2+/Zn)= 0,76 V.

* Xc nh thin cc chun cp Ag+/Ag

Cc phn ng xy ra:

Ag l cc dng (catot): Ag++ e Ag

Hidro l cc m (anot) : H2 2H++ 2e

Phn ng xy ra trong pin:2Ag++ H22Ag

+ 2H+


- 49 -

IV. Dy thin cc chun ca kim

loi: Nguyn tc sp xp cc cp

oxihakh ca kim loi trong dynhthno?

IV. Dy thin cc chun ca kim loi:

Dy thin cc chun ca kim loi l dy

sp xp cc kim loi theo thttng dn thin cc chun .

V. ngha ca dy thin cc

chun ca kim loi:

Hot ng 4:

1. So snh tnh oxihakh:

Quy lut ca dy?

2. Xc nh chiu ca phn ng

oxiha kh:

HS phn tch cc chi tit trong th

nghim xc nh chiu ca phn ng

gia 2 cp oxihakh Cu2+/Cu v

Ag+/Ag

Kt lun: Quy tc

V. ngha ca dy thin cc chun ca

kim loi:

1. So snh tnh oxihakh

MMnE /0 + cng ln th tnh oxiha ca cation

Mn+ cng mnh v tnh kh ca kim loi M

cng yu.

Ngc li th in cc chun ca kim loi

cng nhth tnh oxiha ca cation cng yu

v tnh khca kim loi cng mnh.

2. Xc nh chiu ca phn ng oxiha

kh

Hc sinh phn tch phn ng gia 2 cp

oxihakh:

Cu2+/Cu (E0 = +0,34V) v Ag+/Ag ( E0 =

+0,80V) thy:

Ion Cu2+c tnh oxi ha yu hn ion Ag+.

Kim loi Cu c tnh khmnh hn Ag. Cp oxihakh Cu2+/Cu c th in cc

chun nhhn ca cp oxiha khAg+/Ag.

Kt lun:Cation kim loi trong cp oxiha

K+/K

2,93

Na+/Na

2,71

Mg2+/Mg

2,37

Al +/Al

1,66

Zn +/Zn

0,76

Fe +/Fe

0,44

Ni +/Ni

0,26

Sn +/Sn

0,14

Pb +/Pb

0,13

2H+/H2

0,00

Cu +/Cu

+0,34

Ag+/Ag

+0,80

Au +/A

+1,50


- 50 -

Hc sinh tm hiu thm phn ng

gia 2 cp oxihakh: Mg2+/Mg v

2H+

/H2Kt lun tng ttrn.

3. Xc nh sut in ng chun

ca pin in ha: Hng dn HS

tnh sut in ng chun ca pin

in ha.

Th d: Sut in ng chun ca

pin in ha ZnCu:

E0pin = 0 //0

22

ZnZnCuCu EE ++

= 0,34V (0,76V)

= 1,10V

4. Xc nh thin cc chun ca

c

p oxihakh

:

Bit: 0 ( ) 0,59pin Ni CuE V =

V VECuCu

34,00/2

+=+

Cc dng l cc Cu.

Th : =+0 /2 NiNiE +0,34V0,59V = 0,25V

kh c th in cc chun ln hn c th

oxiha c kim loi trong cp c th in

cc chun nhhn.2Ag+ + Cu Cu2+ + 2Ag

Mg + 2H+ Mg2+ + H2

3. Xc nh sut in ng chun ca pin

in ha

Sut in ng chun ca pin in ha (E0pin)

bngthin cc chun ca cc dng tr

i thin ccchun ca cc m.Sc in

ng ca pin in ha lun l sdng.

4. Xc nh th in cc chun ca cp

oxihakh

Ta c th xc nh c thin cc chun

ca cp oxi hakh khi bit sut in ng

chun ca pin in ha (E0pin) v thin cc

chun ca cp oxi hakh cn li . Th d:

vi pin (Ni-Cu) ta c: 00/

0

/ 22 pinCuCuNiNiEEE = ++

GIO N 12 NNG CAO


- 51 -

BI:

SIN PHN.

I. MC TIU BI HC:

1. Kin thc:Bit sin phn l g?

Bit nhng ng dng ca sin phn trong cng nghip.

Hiu s chuyn dch ca cc ion trong qu trnh in phn: NaCl

nng chy, dung dch CuSO4vi in cc trv in cc tan.

Hiu nhng phn ng ha hc xy ra trn cc in cc trong qu

trnh in phn v vit c phng trnh in phn.

2. Knng: Thc hin c mt sth nghim in phn n gin: pdd CuSO4

vi anot trv anot tan.

Bit xc nh tn cc in cc trong bnh in phn.

Vit c phng trnh ha hc ca phn ng xy ra trn cc in cc

v vit c phng trnh in phn.

Gii c cc bi ton lin quan n sin phn.II. CHUN B:* Th nghim trc quan: Ha cht: dung dch CuSO40,5M

Dng c: ng hnh chU, nt cc in cc, ngun in mt chiu

cng vi bin tr, dy ni cc in cc.

* Mt stranh vvsin phn.

III.HOT NG GING DY:

1. n nh lp:


- 52 -

2. Dy bi mi:

HOT NG CA GV HOT NG CA HSI. KHI NI

M :

Hot ng 1.

Cho HS xem s hnh 5.10 yu

cu HS m tbnh in phn, hot

ng ca bnh in phn?

Pt phn li: NaCl Na+ + Cl

Cc dng: 2Cl(l) Cl2(k) + 2e

Cc m: 2Na+

(l) + 2e 2NaPhng trnh in phn:

2NaCl 2Na + Cl2

Ch phn bit cc ca pin in

ho v cc ca bnh in phn.

GV bsung cc thng tin.

T yu cu HS rt ra kt lun v

sin phn.

I. KHI NI

M

* Thit bin phn gm c:

- Bnh in phn

- 2 in cc.

Cc m v cc dng; ant c ni vi cc (+)

ca ngun in mt chiu; catot c ni vi

cc (-) ca ngun in mt chiu.

* Hot ng ca bnh in phn:Khi c dng in mt chiu chy qua trn in

cc dng (anot) xy ra s oxi ho, trn in

cc m (catot) xy ra skh.

Nu khi nim.

Sin phn l qu trnh oxi ha khxy ra trn

bmt cc in cc khi c dng in mt chiu

i qua cht in li nng chy hoc dung dchcht in li.

II. S IN PHN CC CHT

IN LI

Hot ng 2.

Sdng phng php m thoi.

GV yu cu HS.

- Cho bit cc ion di chuyn trong

dd nhthno ?

- Phng trnh in phn v s

in phn c biu din nh th

II. SIN PHN CC CHT IN LI

1. Sin phn NaCl nng chy.

Khi c dng in mt chiu chy qua.

Cc dng (anot) din ra soxi ha.

Cc m (catot) din ra skh.

Qu trnh oxi ho-khc biu din

pnc


- 53 -

no?

- p MgCl2 nng chy tng t

NaCl nng chyHot ng 5

2. Sin phn dd CuSO4:

a) in phn dd CuSO4vi cc

in cc tr( graphit)

Tho lun phiu hc tp s4

Cu hi 1: Cu to ca bnh in

phn.

Cu hi 2:Hot ng ca bnh in

phn v hin tng xy ra trong

qu trnh in phn.

Cu hi 3:Gii thch

* Khi c dng in mt chiu chy

qua cc ion trong dd dch chuyn

nhthno ?

* Cc qu trnh oxi ho-khdin ra

cc in cc nh th no ? (xt

thin cc chun).

Na++ 1e Na 2Cl--2e Cl2

Phng trnh in phn

22 2dpncNaCl Na Cl +

2. Sin phn dd CuSO4:

a) in phn dd CuSO4vi cc in cc tr

( graphit)

* Bnh in phn l ng chU, 2 in cc bng

graphit, mt in cc m v mt in cc

dng, dd cht in phn l CuSO4.

* Khi cho dng in mt chiu i qua (c hiu

in th1,3 V) c hin tng:

- catot: kim loi Cu bm vo in cc.( cc

m)

- anot: Bt kh O2thot ra. ( cc dng )

* Khi to nn mt in th gia hai in cc,

cc ion SO42-

di chuyn vanot. Cc ion Cu

2+

dichuyn vcatot.

* Catot c th xy ra s kh ion Cu2+ hoc

H2O.

Xt thin cc chun:

E0(Cu2+/Cu) = 0,34 V; E0(H2O/H2)= - 0,83 V.

Nhvy ion Cu2+c tnh oxi ho mnh hn cc

phn tH2O. V vy y xy ra skhcc ionCu2+thnh Cu bm trn catot:

Cu2++ 2e Cu

* anot: C thxy ra soxi ho cc ion SO42-

hoc H2O.


- 54 -

* Vit sin phn.

* Vit phng trnh in phn.

b/ in phn dd CuSO4 vi anot

ng (anot tan) :

Th nghim c m t nh hnh5.12. Hng dn hc sinh gii thch

hin tng.

Xt thin cc chun

E0 (H2O/ O2) = -0,83 V; E0 (SO4

2-/H2O) = 1,70

V.Nh vy H2O c tnh kh mnh hn cc ion

SO42- nn H2O d b oxi ha sinh ra kh O2

anot:

2H2O O2+ 4 H++ 4e

* Cc (-) CuSO4 Cc (+)

(H2O)

Cu2+, H2O H2O, SO42-

Cu2++ 2e Cu 2H2O O2+ 4 H++ 4e

Phng trnh in phn

dd4 2 2 2 42 uSO 2 2 2

dpC H O Cu O H SO+ + +

b/ in phn dd CuSO4 vi anot ng (anot

tan)

Hc sinh quan st th nghim v nhn xt:Anot tan ht, catot khkim loi Cu bm vo

anot (+)Nguyn tCu boxi ha thnh ion

Cu2+i vo dung dch: Cu (r) Cu2+(dd) + 2e.

Anot dn dn b ha tan.

catot ( ) ion Cu2+bi khthnh Cu bm trn

bmt catot: Cu2+(dd)+ 2e Cu(r)

Phng trnh in phn:Cu(r) + Cu

2+(dd) Cu2+(dd)+ Cu (r)

Anot Catot


- 55 -

III. NG DNG CA S IN

PHN

Hot ng 6GV cho HS nghin cu SGK trnh

by ng dng ca sin phn.

Hot ng 7

Tng kt bi hc, ra bi tp vnh.

III. NG DNG CA SIN PHN

1. iu chkim loi.

2. iu chmt sphi kim (H2; O2...)3. iu ch mt s loi hp cht (KMnO4,

NaOH, H2O, nc giaven...)

4. Tinh chmt skim loi: Cu, Pb, Zn, Fe, Ag,

Au...

5. Min...


- 56 -

GIO N 12 CBNBI:

IU CHKIM LOII. Mc tiu ca bi hc.

1.Kin thc.Bit nguyn tc chung viu chkim loi.

Hiu cc phng php c vn dng iu ch kim loi. Mi phng phpthch hp vi siu chnhng kim loi no. Dn ra c nhng phn ng ho

hc v iu kin ca phn ng iu chnhng kim loi cth.

2.KnngBit gii cc bi ton iu chkim loi, trong c bi ton iu chkim loi

bng phng php in phn khng hoc c sdng nh lut Faraay.

II. Chun b

Bng Dy in ho chun ca kim loi, Bng tun hon cc nguyn tho hc. HS xem li Bi 16nh.

III. Hot ng dy hc

Hot ng ca gio vin Hot ng ca hc sinh

Hot ng 1

GV thng bo, trong tnhin chc mt

s t kim loi tn ti trng thi tdo,

nh Au, Pt, Hg ... Hu ht cc kim loikhc u di dng cc hp cht ho hc

(oxit, mui)., kim loi tn ti dng ion

dng.

GV t cu hi, nguyn tc iu chkim

I. NGUYN TC IU CH KIM

LOI.

Thc hin skh:

Mn++ ne M


- 57 -

loi l g ? Bng cch no c thchuyn

nhng ion kim loi thnh kim loi tdo ?

Hot ng 2.Cskhoa hc ca phng php nhit

luyn iu chkim loi l g?

- Dn ra mt s kim loi c iu ch

bng phng php nhit luyn, vit

phng trnh phn ng ho hc, iu

kin ca nhng phn ng ny l g ?- Nhng kim loi no thng c iu

chbng phng php nhit luyn?

Hot ng 3. GV hng dn HSnghin cu SGK :

- Csca vic iu chkim loi bng

phng php thuluyn l g?

- Dn th d v vit phng trnh phn

ng ho hc.

II. PHNG PHP IU CH KIM

LOI

1. phng php nhit luyn

- C s: Kh nhng ion kim loi trong

oxit nhit cao bng cc cht kh

nh: C, CO, H2hoc Al, KL kim, KL

kim th

- V d:0

0

2 3 2

2 2

3 2 3t

t

Fe O CO Fe CO

PbO H Pb H O

+ +

+ +

- Dng trong CN, iu chnhng kim

loi hot ng trung bnh.

2.Phng php thuluyn

- HS nu:Dng ho cht thch hp nhH2SO4,

NaOH, NaCN tch hp cht ca kim

loi ra khi qung. Sau dng cht kh

khion kim loi thnh kim loi tdo

- Th d:

Dng Fe khion Cu2+trong dd mui

ng

Fe + CuSO4 FeSO4 + Cu

2 2Fe Cu Fe Cu+ ++ +


- 58 -

- Phng php thu luyn c dng

iu chnhng kim loi no?

Hot ng 4.- Csca phng php in phn iu

chkim loi l g?

- Nhng kim loi no c th c iu

chbng phng php in phn?

C my loi in phn.?

- Phng php nydng iu ch kim

loi yu.

3. Phng php in phn.

HS trli:

Phng php in phn dng nng lng

ca dng in gy ra sbin i ho

hc, l phn ng oxi ho - kh.

- Phng php in phn c thiu ch

c nhng kim loi hot ng mnhnh: K, Na, Ca, Mg, Al..

a/ in phn nng chy

V d: in phn Al2O3nng chy

Catot (cc m): 3 3Al e Al+ +

Anot (cc dng): 2 22 4O O e +

Phng trnh in phn:

2 3 22 4 3dpncAl O Al O +

b/ in phn dung dch

c thc dung iu chkim loi

hot ng trung bnh hoc yu bng cch

in phn mui ca chng.

V d: in phn dung dch CuCl2iu chCu.

Catot: 2 2Cu e Cu+ +

Anot: 22 2Cl Cl e +


- 59 -

- Dn th diu chkim loi hot ng

trung bnh bng phng php in

phn,th d iu ch Zn (nguyn liu,

trng thi,s v phng trnh

in phn).

- Gio vin trnh bi nh lut Faraday

Hot ng 5. Cng cbi hc.

* GV cng cbi hc bng cch cho HS

lm mt sbi tp sau :

Bi tp 1 trong SGK. Bi tp c dn lm th dtrong

Phng trnh in phn:

dd2 2

dpCuCl Cu Cl +

- Th d: Sin phn dung dch

ZnSO4

Cc (-)

Zn2+, H2O

ZnSO4

(dd)

Cc (+)

SO42-, H2O

Zn2++2eZn 2H2O4H++O2+ 4e

Phng trnh in phn:2 ZnSO4+ H2O 2 Zn + 2 H2SO4+ O2

III. NH LUT FARADAY

- Cng thc: Error! Objects

cannot be created from editing field

codes.


- 60 -

PHN III. KT LUN V XUTI. KT LUN

Vic ging dy ni dung kin thc in ha hc cho hc sinh trng phthng l ht

sc quan trng v cn thit. Sau mt thi gian nghin cu v thc hin, kha lun ny

hon thnh nhng vn sau:

- Nghin cu cs l lun cc vn in ha hc trong chng trnh ha hc ph

thng.

- Nghin cu h thng ha nhng kin thc vin ha hc trng trung hc ph

thng.

- Nghin cu cu trc chng trnh cc bi dy chng trnh trung hc phthng.

- Phn tch shnh thnh khi nim in ha hc tbc trung hc csn trung hc

phthng thy y l phn kin thc quan trng cn phi nm vng.

- Tin hnh iu tra mc nm kin thc in ha hc ca hc sinh khi lp 12,

gm 2 ban: ban nng cao v ban cbn vi 4 lp: 2 lp 12 ban nng cao v 2 lp 12

ban cbn trng THPT Lai Vung II. Sau khi xl kt quv thng k sliu, ti

c nhn xt sau:+ Hc sinh nm c phn no kin thc cbn vin ha hc tuy nhin cha nm

vng mt cch chc chn vnhng vn bn cht ca in ha hc.

+ Phn ln hc sinh cn tra lng tng khi p dng l thuyt in ha hc vo phn

bi tp.

Sau khi tm hiu csl lun v iu tra tnh hnh nm kin thc ca hc sinh vphn

kin thc in ha hc, ti mnh dng a ra mt snhn xt v gii php nhm

nng cao hiu quging dy phn kin thc ny. ng thi ti cng thit kmt sgio n c lin quan n kin thc vin ha ha hc trng THPT ca khi lp

12.


- 61 -

II. XUT V KIN NGH

gip cho vic ging dy mn ha hc, c bit l vic hnh thnh v pht trin kin

thc cbn m cthy l kin thc in ha hc t hiu qucao ti xin c mtskin nghsau:

- i vi ni dung chng trnh ha hc phthng hin nay, khi lng kin thc a

vo chng trnh l kh nhiu nhng thi gian ln lp li qu t nn gio vin khng c

thi gian luyn tp, mrng kin thc cho hc sinh. V th, cn phi tng thm thi

gian ln lp (stit).

- Gio vin cn nn cho hc sinh nghin cu, xem xt cc vn ca kin thc trn

nhiu kha cnh khc nhau, kt hp vi nhng l thuyt trc c hc.

- i vi lnh o nh trng i hc, em xin c mt snghsau:

+ Tng cng tit tp ging sinh vin c thging dy tt ccc bi trong chng

trnh THPT. Trong cc tit , gio vin nn gp phng php ging dy ca tng

bi, tng phn cho sinh vin.

+ Tchc cc bui nghe bo co kinh nghim ca cc gio vin trng trung hc ph

thng vphng php ging dy cc ni dung kh, tru tng chng hn nh: Pin in

ha, thin ha, sut in ng, in phn in cc tan..nhm gip cho sinh vin

c thm kinh nghim khi vo ngh.

- i vi gio vin ang ging dy trng trung hc phthng hay cc sinh vin cn

ang ngi trong gh nh trng u cn phi lun lun trao di kin thc chuyn mn

ca mnh mt cch vng chc nht, t kt hp vi cc phng php dy hc thch

hp truyn t kin thc cho hc sinh mt cch tt nht.

- Trong thi gian gn y, ng dng cng nghthng tin trong dy hc ha hc ang

c sdng mt cch rng ri. V thbn than mi gio vin, sinh vin u phi lun

tm ti, hc hi, mmang tri thc ca mnh, tip cn vi cng nghhin i ca khoa

hc kthut phc vcho vic ging dy ca mnh c tt nht.

lv giang day mot so noi dung hh thpt - dien hoa hoc

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