Thiết kế bài giảng hóa học 12 (tập 2) phần 1

De kliac sau kien thiic ve lien ket kim loai vai cac lien ket khac GV yeu cau HS nghien ciiu SGK va nhan xet: - Lien ket kim loai la lien ket dugc hinh thanh giQa cac nguyen tii va ion k

CAO C U GlAC (Chii bien)

Thiet kebdi gidng

ffi

N H A X U A T B A N H A N 0 I

TS CAO CU G I A C (Chu bien) - ThS HO THANH THUY

THIET KE BAI GIANG

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TflTP HW

Chirong 5 DAI ClTOfNG VE KIM LOAI

Bai 17 V! TRI CUA KIM LOAI TRONG B A N G

T U A N H O A N V A C A U T A O C U A KIM LOAI

A MUC TIEU BAI HOC

1 Kiln thii'c

HS biit:

• Vi tri cua kim loai trong bang tuan hoan

• Cau tao cua nguyen tu kim loai va cau tao tinh the ciia kim loai

• Lien ket kim loai

HS hieu:

Mot so kieu cau true tinh the kim loai (mang tinh the luc phucmg, lap phuang tam dien, lap phuang tam khoi)

2 KT nang

• Suy dien: Tu vi trf cua kim loai suy ra cau tao va tinh chat

• So sanh: Lien ket kim loai vai cac loai lien ket khac

3 Tinh cam, thai dp

Vai tro kim loai trong cuoc s6ng, bao ve va khai thac hop li tai nguyen, khoang san cua dat nuac

B C H U A N B! C U A GV VA HS

• GV: - Bang tuan hoan cac nguyen to hoa hoc

- Bang phu ve so do cau tao va ghi ban kinh cua nguyen tu cua cac nguyen to thuoc chu ki 2

- Tranh ve 3 kieu mang tinh thi cua kim loai

» HS: - Xem truac noi dung bai hoc

- Tap lam mot so mo hinh ve tinh thi kim loai

C TI^N T R I N H DAY - HOC

Hogt dgng 1

I VI TRI CUA KIM LOAI TRONG BANG TUAN HOAN

GV chieu bang tuan hoan co to mau

cac kl hieu nguyen to len man hinh

(hoac treo bang tuan hoan len bang)

cho HS thao luan

GV huang dan HS tim ra vi tri cua

kim loai trong bang:

- Kim loai la cac nguyen to dugc to

mau vang a trong bang tuan hoan

- Phi kim la cac nguyen to dugc to

mau tim a trong bang tuan hoan

Yeu cau HS xac dinh vi tri cua kim

loai

GV bd sung: Ngoai each xac dinh a

tren thi kim loai nam a:

- Khoi nguyen to s (trir H, He)

- Mot so a khoi nguyen to p

- Toan bo khoi nguyen to d, f

GV yeu cau HS riit ra ket luan ve vi

HS quan sat thao luan cho ket qua:

Vi tri kim loai gom:

- Nhom IA din VIA (Nhom IA nhom IIIA tru B) va mot phan IVA,VA, VIA

- N h o m l B d I n V I I I B

- Hai ho Lantan va Actini

HS thao luan cho ket qua:

tru H nhom

Hogt dgng cua GV Hogt dgng cda HS

- Kim loai chiem da so vi tri trong bang tuan hoan

- Kim loai nam a phia dual ben trai cua bang tuan hoan

II CAU TAO CUA KIM LOAI

Hogt dgng 2

I Cau tao nguyen tu"

GV: Yeu cau HS viet cau hinh

electron nguyen tu ciia cac nguyen to

kim loai nNa, ^Mg, 13AI, 26Fe va

cac nguyen to phi kim jjP jgS, 17CI

GV: So sanh so electron a lop ngoai

Cling cua cac nguyen tii kim loai, phi

kim tren va riit ra ket luan

GV diing bang phu ve sa do cau tao

va ghi ban kinh ciia nguyen tii thuoc

chu ki 2 (ban kinh nguyen tii dugc

bilu dien bang nanomet, nm):

HS viet cau hinh ciia cac nhom

- Kim loai:

iiNa: Is 2s 2p 3s i2Mg: Is 2s 2p 3s*' nAl: ls"2s 2p 3s 3p 26Fe: ls''2s 2p 3s 3p 3d 4s

- Phi kim:

15P: Is 2s 2p 3s 3p igS: Is 2s 2p 3s 3p 17CI: ls"2s 2p 3s 3p

So electron a Idp ngoai ciing cua kim loai tii 1-3 electron con phi kim thi thuang co nhieu electron (tir 4-^7 electron tru H va khi hiem)

Ket luan: Nguyen tir ciia hau hit cdc

nguyen td kim logi deu cd it electron a lap ngodi cung (1-3 electron)

Hogt dgng cua GV Hogt dgng cda HS

llNa i2Mg 13AI u S i ]5P 16S 17CI

0.157 0,136 0,125 0,117 0,110 0,104 0,099

Yeu cau HS riit ra nhan xet ve su bien

thien ciia dien tich hat nhan va ban

kinh nguyen tu

HS quan sat cac so lieu va nhan xet:

Trong cung chu ki, nguyen tic ciia nguyen

to kim logi cd bdn kinh nguyen tic lan han

vd dien tich hat nhdn nhd han so vai nguyen tic cita nguyen to phi kim

Hogt dgng 3

2 Cau tao tinh the

GV nhic lai mgt s6 kilu tinh thi da I HS nghien cuu SGK va len bang ve lai

hgc a lap 10 Sau do HS nghien ciiu

SGK ve noi dung cau tao tinh the kim

loai

Yeu cau HS:

- Neu cau triic cac loai tinh the (mo ta

hinh ve)

- Nhan xet ve do dac kbit cua mang

tinh the kim loai

- Lay vi du mgt so kim loai

- So sanh cac loai tinh the kim loai

cau triic tinh the kim loai

a) Mang tinh thi luc phwffng

- Cac nguyen tii, ion kim loai nam tren

cac dinh va tam cac mat cua hinh luc giac diing va 3 nguyen tu, ion nam phia trong ciia hinh luc giac

- Nguyen tii va ion chiem 74% con lai 26% la khong gian trong

- Vidu: Be, Mg, Zn,

b) Mang tinh thi lap phirffng tam dien

Hogt dgng cda GV Hogt dgng cua HS

GV giai thieu: Trong tinh the kim

logi, nguyen tu vd ion kim logi ndm a

nhiing nut mang tinh the Cdc

electron hod tri lien kit yeu vai hat

nhdn nen de tach ra khdi nguyen tic vd

chuyin dgng tu do trong mang tinh

thi

- Cac nguyen tu, ion kim loai nam tren

cac dinh va tam cac mat cua hinh lap phuang

- Nguyen tu va ion chiem 74% con lai 26% la khong gian trong

- Vidti: Cu, Ag, Au, Al,

c) Mang tinh thi lap phutfng tdm khdi

- Cac nguyen tu, ion kim loai nam tren

cac dinh va tam ciia hinh lap phuang

- Nguyen tu va ion chiem 68% con lai 32% la khong gian trong

-Fz't/w.-Li,Na,K,V,Mo,

Hogt dgng 4

3 Lien ket kim loai

GV: Dua tren c4u tao mang tinh the

kim loai, phan tich, dien giang kien

thiic lien ket kim loai

Cl trang thai long va ran, cac nguyen

tii kim loai lien ket vai nhau bang mgt

Hogt dgng cua GV

kieu lien ket hoa hgc rieng ggi la lien

kit kim logi

GV yeu cau HS nghien ciiii SGK va

neu khai niem lien ket kim loai

De kliac sau kien thiic ve lien ket kim

loai vai cac lien ket khac GV yeu cau

HS nghien ciiu SGK va nhan xet:

- Lien ket kim loai la lien ket dugc hinh thanh giQa cac nguyen tii va ion kim loai trong mang tinh the do su tham gia ciia cac electron tu do

HS thao luan cho ket qua

+ Lien ket kim logi v&i lien kit cong hod tri

Gidng nhau: Deu co su gop chung, diing

+ Lien kit kim logi v&i lien kit ion

Giong nhau: Deu co ban chat la lire hut

tinh dien giira ion duang vai phan tir mang dien tich am

Khdc nhau:

- Lien ket ion la luc hut tmh dien giiia

ion am vai ion duong

- Lien ket kim loai la luc hut tmh dien giira electron vai ion kim loai

Hogt dgng cua GV Hogt dgng cua HS

Hogt dgng 5

CUNG CO B A I V A B A I T A P V E N H A

GV chieu cac bai tap sau len man

hinh cho HS thao luan ciing c6 noi

dung bai hgc:

Bai 1 Lien ket kim loai la lien ket

dugc hinh thanh do:

A Su gop chung electron hoa tri ciia

cac nguyen tir kim loai

B Cac electron tu do trong kim loai

phan xa tot nhiing tia sang tai

C Do su gop chung mgt so cap

electron hoa tri

D Sir gop chung toan bg electron cua

cac nguyen tir kim loai

Bai 2 Cho cac nguyen to co so hieu

Bai tap ve nha: 1, 2, 3, 4, 5, 6, 7, 8, 9 (SGK)

D HU-aNG DAN GIAI BAI TAP TRONG SGK

4 Chgn dap an B

5 Chgn dap an D

6 Chgn dap an B

7 Chgn dap an C

nNaOH = 0,03.1 =0,03 (mol) n^^so, = 0,15.0,5 = 0,075(mol) Phuang trinh hoa hgc:

M + H2SO4 -^ MSO4 + H2 (1) H2SO4 + 2NaOH -^ Na2S04 + 2H2O (2)

0,015(mol) <- 0,03 (mol) nH,so,«(i) = 0 , 0 7 5 - 0 , 0 1 5 = 0,06(mol) ^ UM = 0,06 (mol)

tir Cl tao muoi

nimu6i = nikim loai + mg6c axit = 15,4 + 35,5.0,6 = 36,7 (gam)

9 Phuang trinh hoa hgc:

A + CI2 -> ACI2

Fe + ACI2 -^ FeCb + A

1 A - 5 6 0,8 Taco: — = => x X 0,8 A - 5 6

Theo bai ra, ndng do FeCl2 trong dung dich la 0,25M nen so mol FeC^ la

Bai 18 T I N H C H A T CUA KIM LOAI DAY DIEN HOA CUA KIM LOAI

A MUCTIEUBAI HOC

1 Kiln thiFC

HS biet:

• Tinh ch4t vat li chung va tinh chit hoa hgc chung ciia kim loai

• Day dien hoa ciia kim loai

HS hiiu:

Nguyen nhan gay ra tinh chit vat li chung va tinh chit hoa hgc chung cua kim loai

2 KTnang

• Ren luyen kT nang suy dien: Tir vi tri cua kim loai trong bang tuan hoan, suy

ra ciu tao va tir ciu tao suy ra tinh chat ciia kim loai

• Ren luyen kT nang giai cac bai tap ve kim loai

3 Tinh cam, thai do

Hiiu dugc tam quan trgng cua kim loai trong cugc song tir do co biet cac sir dung kim loai mgt each hgp li va tiet kiem

B C H U A N Bj CUA GV VA HS

• GV: - Hoa chit: Dinh sit, day sit, day dong, day nhom, hat kem, binh dimg

khi clo, dung dich HCl, dung dich H2SO4 loang, dung dich HNO3 loang

- Dung cu: Dung cu thi nghiem chung minh cac kim loai c6 do dan nhiet khac nhau (neu c6)

- Ong nghiem, c6c thuy tinh, den c6n, gia thi nghiem

• HS: Xem truac noi dung bai hgc

11

C T | £ N TRiNH DAY- HOC

Hocit dgng cua GV Hogt dgng cua HS

Hogt dgng 1

I TINH CHAT VAT LI

1 Tinh chat vat li chung

GV giai thieu: 0 dieu kien thuang, cac

kim loai deu a trang thai ran (trir Hg),

CO tinh deo, dan dien, dan nhiet va co

anh kim

Vay the nao la tinh deo, tinh dan dien

tinh dan nhiet, anh kim? va tai sao kim

loai CO cac tinh chat tren chung ta se

nghien ciru timg tinh chat cu the

GV bo sung: Kim loai co tinh deo Ion

nhat la Ag sau do la Al, Cu

HS thao luan nhan xet va cho ket qua

- Tinh deo cua vdt lieu la tinh bi bien

dang khi chiu ap luc ben ngoai hoac nhiet tac dung va van giir dugc trang thai bien dang do khi thoi tac dung

- Gidi thich: Kim loai co tinh deo la vi

cac ion duang trong mang tinh the kim loai CO the trugt len nhau de dang ma khong tach ra khoi nhau nha nhiing electron tu do chuyen dgng dinh ket chung vai nhau

T h©:©©|

— M © © © ^ F©:©*©r

l» • ^ 1

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b) )

m loai

Hogt dgng cua GV Hogt dgng cua HS

b) Tinh dan diin

GV yeu cau HS nghien cim SGK va

cho biet:

- The nao la tinh dan dien?

Giai thich?

GV bo sung: Kim loai dan dien tot nhat

la Ag, sau do den Cu, Au, Al, Fe,

GV bo sung: Thuong cac kim loai dan

dien tot ciing dan nhiet tot

- Tinh ddn diin la tinh chat cua vat lieu

khi gan vao 2 dau vat lieu mgt hieu dien the thi tao thanh dong chuyen dai co huang ciia electron tir cue am sang cue duang

- Gidi thich: Do trong kim loai c6 cac

electron ty do chuyen dgng hon loan trong mang tinh the, khi c6 hieu dien the lap tire cac electron tu do chuyen dgng thanh dong co huang tao ra dong dien

- Tinh ddn nhiet la tinh chat ciia vat

lieu CO the truyen nang lugng (nhiet) tir

vi tri nay den vi tri khac

- Gidi thich: Do kim loai co mat cac

electron tu do trong mang tinh the Cac electron trong viing nhiet do cao co dgng nang Ion, chuyen dgng hon loan

va nhanh chong sang vimg co nhiet do thap hon, truyen nang lugng cho cac ion duong a vimg nay nen nhiet lan truyen dugc tir vimg nay den vimg khac trong khoi kim loai

13

GV giai thieu: Ngoai cac tinh chit tren

kim loai con co mgt so tinh chit vat li

khac nhu: Tinh cimg, khoi lugng rieng,

nhiet do nong chay, nhiet do soi

Vidu:

Kim loai cimg nhat la Cr

Kim loai nang nhat la Os

Kim loai co t°^ thip nhit la Hg(-39°C)

Kim loai c6 t°^ cao nhit la W(3410°C)

GV huang dan HS ket luan vin dl

Nguyen nhan gay ra tinh chat vat li

chung cua kim loai?

Hogt dgng cua HS

HS thao luan cho ket qua:

-Anh kim la anh sang thu dugc khi kim

loai hap thu anh sang trang va phan xa

ra anh sang c6 buac song dac trung cho timg kim loai

- Gidi thich: Do cac dam may electron

tu do trong tinh the kim loai hap thu phan xa hau het nhiing tia sang nhin thay dugc, do do kim loai co ve sang lap lanh ggi la anh kirn

HS nhan xet: Tinh chdt vdt li chung ciia

kim logi gdy nen bdi su cd mat cua cdc electron tu do cd mat trong tinh thi kim logi

Hogt dgng cua GV Hogt dgng cua HS

Hogt dgng 2

II TINH CHAT HOA HOC

GV huong dan HS nit ra tinh chit hoa

hgc ca ban cua kim loai:

- Dac diem cau tao cua nguyen tir kim

loai (so electron hoa tri)

- Du doan xu huang ciia kim loai de c6

dugc cau hinh ben cua khi hiem

- Suy ra tinh chat chung cua kim loai

Hogt I

1 Tac dung

a) Tdc dung v&i clo

GV lam thi nghiem: Dot day sat nong

do sau do dua vao binh dung day khi

clo, yeu cau HS quan sat:

- Neu hien tugng

- Giai thich

- Viet phuong trinh hoa hgc minh hoa

- Su thay doi so oxi hoa cua Fe va CI2

HS thao luan nhan xet cho ket qua sau:

- Kim loai thuong co it electron(l-3e)

a lap ngoai ciing

- Xu huong cho electron de dat dugc cau hinh ben

- Tinh chit chung cua kim loai la tinh khir:

M > M"* + ne

long 3

vol phi kim

HS quan sat thi nghiem va riit ra nhan xet

- Hien tugng: Day Fe chay manh trong

khi clo tao ra khoi mau nau

- Gidi thich: Vi Fe da khir clo tao ra

nhiing hat chit ran sat (III) clorua mau nau

- Phuong trinh hoa hgc 2Fe° + 3CI2 - ^ ^ 2 FeCL,

- Trong phan ung nay:

Hogt dgng cda GV

GV nhan xet bo sung:

- Hau het cac kim loai deu tac dung

true tiep vai clo

- Vai cac halogen khac thi tuy vao

mire do oxi hoa ciia halogen va tinh

khir cua kim loai ma cho san pham

Hau het cac kim loai deu tac dung true

tiep vai oxi (trir Ag, Au, Pt )

Trong cac phan img kim loai thuong

0 - 2

khir oxi tir: 0 >0

Tuy vao dieu kien phan irng ma san

pham san pham thu dugc la khac nhau

GV yeu cau HS viet cac phuong trinh

phan img minh hoa

HS thao luan cho ket qua cac trinh phan ling:

(Fe + O2 -> nhieu san pham)

c) Tdc dung v&i luu huynh

GV yeu cau HS nhan xet kha nang oxi

hoa ciia nguyen to S

GV nhan xet bo sung:

- Nhieu kim loai tac dung dugc vai S a

nhiet do cao, rieng Hg tac dung dugc a

Hogt dgng cda GV Hogt dgng cua HS

~ Kim loai bi oxi hoa len so oxi hoa

trung binh nhu: Fe -^-^ FeS

Yeu cau HS viet cac phan img minh

hoa

Fe + S -> FeS (khong tao ra Fe2S3 va FeS2)

Hogt dgng 4

2 Tac dung vol dung dfch axit

a) V&i dung dfch HCl, H2SO4 hang

GV neu van de: Cac dung dich axit

HCl, H2SO4 loang co tinh oxi hoa

Nhung tai sao chi tac dung dugc vai

cac kim loai dung truac H trong day

hoat dgng?

San pham phan irng thu dugc la gi?

GV huong dan HS Giai quylt vin dl,

Viet cac phucmg trinh hoa hgc minh

hoa

GV bo sung: Cac kim loai da hoa tri

thuang bi oxi hoa len so oxi hoa trung

0

Fe

+2

Fe binh nhu: Fe, Cr.,

b) V&i dung dich UNO3, H2SO4 dgc

GV dat vin dl: Tai sao HNO3, H2SO4

dac lai tac dung dugc vai hiu hit cac

kim loai (trir Au, Pt) Trong khi axit

HS thao luan de giai quyet van de:

Cac phan tir axit HCl, H2SO4 loang c6 tinh oxi hoa do nguyen tir H trong phan tir axit the hien nen chi tac dung vai cac kim loai co tinh khir manh hon hidro San pham phan ung la muoi va H2 Phuong trinh phan img:

Fe +HC1 -^ FeCl2 + H 2 t

Mg + H2SO4 -^ MgS04 + H s t

17

Hogt dgng cua GV

HCl, H2SO4 loang khong co dugc tinh

chat nbu vay?

GV huong dan HS giai quyet van de

- So oxi hoa ciia cac nguyen to trong

phan tir axit HNO3, H2SO4

- Kha nang oxi hoa ciia cac nguyen to

- S a n pham ciia phan img

Hogt dgng cua HS

Viet cac phuang trinh phan ung minh

hoa

GV nhan xet va bo sung:

- Tuy vao dieu kien phan ling ma cho

ra cac san pham khir khac nhau

- Thucmg cac kim loai bi oxi hoa len so

oxi hoa cao Vi du: Fe

- HNO3 va H2SO4 dac, ngugi lam thu

dgng hoa Al, Fe, Cr

HS thao luan dl giai quylt vin dl duoi

su huong dan cua GV:

nhu: Cu, Ag thi chi co the la N, S

- San pham cua su oxi hoa

S la: SO2, S, H2S Nia: NO2, NO, N2O, N2, NH3, (NH4NO3)

Phuong trinh hoa hgc:

3Cu + 8HNO3 -> 3Cu(N03)2 + 2N0 T

+ 4H2O 2Ag + 2H2SO4 ^ ^ Ag2S04 + SO21

+ 2H2O

Fe + 6HN03dac ^ ^ Fe(N03)3

+ 3 N 0 2 t +3H2O

Hogt dgng cua GV Hogt dgng cua HS

Hogt dgng 5

3 Tac dung voi nu-dc

GV yeu cau HS viet cac kieu phan img

ciia kim loai ma HS da tirng bilt?

GV thong bao: Vay nhung kim loai nao

thi CO phan img theo kilu cua Na, theo

kieu cua Fe Co thi xet nhu sau:

- Cac kim loai nhom IA, IIA (trir Be,

Mg) CO tinh khir manh tac dung vai

nuac a nhiet do thuang tao ra baza tan

va hidro

- Cac kim loai co tinh khir yeu hon tac

dung vai nuac a nhiet do cao tao ra

oxit kim loai va hidro

- Cac kim loai co tinh khir rat ylu nhu

Ag, Au, Pt thi khong cac dung dugc

vai nuac

HS viet phuang trinh hoa hgc

2Na + 2H2O -^ 2NaOH + H21

Fe + H2O - ^ ^ FeO + H21

HS ghi bai

Hogt dgng 6

4 Tac dung vol dung dich muoi

GV lam thi nghiem: Ngam 1 thanh sat

da (cao sach gi) vao dung dich CUSO4

loang sau mgt thai gian, cho HS quan

sat va yeu cau

- Quan sat hien tugng

- Giai thich

HS quan sat va nhan xet

- Hien tuang: dung dich CUSO4 nhat

mau dong thofi tren thanh sat co Cu kim loai mau do bam vao thanh sat

- Gidi thich: Fe co tinh khir manh ban

Cu Khu Cu^^ thanh Cu

19

Hogt dgng cua GV

- Viet phuong trinh hoa hgc minh hoa

GV lam tiep thi nghiem: Cho 1 mau

Na vao dung dich CUSO4 loang Cho

HS quan sat va yeu cau:

- Quan sat hien tugng

- Giai thich bang phuong trinh hoa

hgc

GV yeu ciu HS so sanh 2 thi nghiem

de rut ra ket luan

GV khic sau kiln thirc: Dieu kien kim

loai tac dung vai dung dich muoi tao ra

kim loai mai

- Kim loai c6 tinh khir manh hon kim

loai trong muoi

- Kim loai khong tac dung vai nuac a

- Phuong trinh hoa hgc

Fe + CUSO4 -> FeS04 + Cu

HS quan sat va nhan xet

- Hien tugng: Thay mau Na tan dan

ddng thai co khi bay ra va dung dich nhat mau, c6 ket tua mau xanh nhat xuat hien

- Gidi thich: Ban diu miu Na tac dung

vai nuac lam mau Na tan va c6 khi

2Na + 2H2O -^ 2NaOH + H2 T

Sau do NaOH trao doi vai CUSO4 tao thanh kit tua Cu(0H)2

CuS04+2NaOH^Cu(OH)2 + Na2S04

Kit ludn: Tuy vao ban chat kim loai cho

vao la gi? ma san pham tao ra la khac nhau

HS ghi bai

Hogt dgng cua GV

GV bo sung ngoai cac tinh chit tren thi

kim loai con c6 cac phan img khac:

- Tac dung vai oxit kim loai: vi du Al

tac dung dugc vai Fe203, Fe304,

CuO

- Tac dung vai oxit phi kim Vi du: Mg

CO the khir dugc CO2, SO2

- Kim loai luang tinh tac dung voi

dung dich bazo

Yeu cau HS viet phuong trinh hoa hgc

minh hoa

Hogt dgng cua HS

Phuong trinh hoa hgc

2AI + Fe203 ^ ^ AI2O3 + 2Fe

Mg + CO2 ^ ^ MgO + CO

2Al+2NaOH+2H20^2NaA102 + 3H2

Hogt dgng 7

III DAY DIEN HOA CUA KIM LOAI

1 Cap oxi hoa- khu* cua kim loai

GV yeu cau HS

- Viet qua trinh nhuong, nhan electron

ciia cac kim loai va ion sau: Cu, Ag, Fe,

Ag Cu , Fe

- Cho biet vai tro ciia cac chat trong

ban phan img

GV giai thieu: Dang oxi hoa va dang

khir ciia ciing mgt nguyen to tao nen

cap oxi hoa-khir cua kim loai:

Bilu diln: Dang oxi h o a /

/ Dang khu Yeu cau HS viet cac cap oxi hoa- khir

cho cac nguyen to kim loai tren

GV bo sung: Ngoai cap tren con mgt s6

cap dac biet nhu: ^ ^ ' / ^ ^ j ^ ^ ' / ^ ^

HS thao luan cho ket qua

HS viet cac cap oxi hoa khir:

A g V C u - y F e ^ y / A g ' / C u ' / F e

21

Hogt dgng cua GV Hogt dgng cua HS

2 So sanh tinh chat cua cac cap oxi

hoa-khu-GV lam thi nghiem 1: Cho mgt 1 it bgt

Cu vao dung dich AgN03 lac kT sau mgt

thod gian cho HS quan sat yeu cau HS:

- Neu hien tugng

- Viet phuang trinh dang ion thu ggn

- Nhan xet ve tinh oxi hoa, tinh khir

ciia cac ion kim loai va kim loai

GV Nhac lai thi nghiem: Cho mgt

thanh Fe vao dung dich CUSO4 loang

lac kl sau 1 thai gian cho HS quan sat

yeu cau HS

- Viet phuong trinh dang ion thu ggn

- Nhan xet ve tinh oxi hoa, tinh khir

ciia cac ion kim loai va kim loai

GV yeu cau HS sap xep:

- Tinh oxi hoa cua cac ion kim loai

theo chieu tang dan

- Tinh khir cua cac kim loai theo chieu

giam dan

GV nhan xet: Tir 2 thi nghiem tren ta

CO dugc thir tu ciia mgt so cap oxi hoa

khir Neu lam nhieu thi nghiem ta se c6

day dien hoa cua kim loai nhu sau

HS quan sat thi nghiem 1 va nhan xet:

Hien tugng: Thay dung dich xuat hien

2+

mau xanh nhat ciia Ion Cu dong thai thay xuat hien Ag kim loai

Phuong trinh hoa hgc

Cu + 2Ag^ -^ Cu^^ + 2Ag

Nhan xet:

- Cu CO tinh khir manh ban Ag

- Ag CO tinh oxi hoa manh hon Cu

Phuong trinh hoa hgc

Tinh khir Fe > Cu > Ag

Hogt dgng cua GV Hogt dgng cda HS

3 Day dien hoa ciia kim loai

GV giai thieu khi so sanh nhieu cap oxi

hoa-khir ta co day dien hoa nhu sau:

r N_a^ M_r Al^^Zi^^Fi^Ni^^S^^Pb''

K Na Mg Al Zn Fe Ni Sn Pb

tfCif'Ag^Au^^

H2 Cu Ag Au

GV theo chieu miii ten thi tinh oxi hoa,

tinh khir bien doi the nao?

GV bo sung: Cap H /H2 la cap dua vao

de so sanh ngoai ra con c6 cap

Fe /Fe nam giira cap Cu va Ag

HS nhan xet tra lai

Tinh oxi hoa ciia ion kim loai tang

K Na Mg Al Zn Fe Ni Sn Pb FTof^Ag^Au^"

H2 Cu Ag Au Tinh khir ciia kim loai giam

4 Y nghia cua day dien hoa cua kim loai

GV giai thieu: Day dien hoa cua kim

loai cho phep du doan chieu cua phan

img giira 2 cap oxi hoa - khir theo quy

tac a (anpha):

Chat oxi hoa yeu Chat oxi hoa manh

Chat khir manh Chat khir yai

Phan img giira 2 cap oxi hoa - khir se

xay ra theo chilu, chat oxi hoa manh

nhit se oxi hoa chat khir manh nhat,

sinh ra chat oxi hoa yeu hon va chat

khir yeu hon

GV yeu cau HS lay vi du minh hoa

2+ 2+

Cho cap Fe /Fe va Cu /Cu

HS nghe giang va ghi bai

HS lay vi du minh hoa:

23

Hogt dgng cua GV

GV luu y trong day dien hoa:

- Cac cap oxi hoa-khir xa nhau nhit

trong day dien hoa thi phan ung xay ra

truac

- Khi cho kim loai A vao dung dich

muoi B thi phan ung xay ra nhu thi

nao (neu c6 phan ting)?

GV chieu bai tap sau len man hinh cho

HS thao luan

Khi cho hSn hgp Mg, Zn vao dung dich

chiia cac mu6i Cu(N03)2, AgN03 Neu

thii tu cac phan img xay ra trong dung

HS thao luan cho ket qua

Thii ty cac kim loai trong day dien hoa

Zn + Cu^^ -^ Zn^^ + Cu

- Neu Ag hit thi Mg tac dung vai

Cu 2+

Mg + C u 2+ Mg^^ + C u Sau do CO thi CO phan ling nlu Mg hit

Zn + Cu^^ -^ Zn^^ + Cu

Hogt dgng cua GV Hogt dgng cua HS

GV chieu cac bai tap sau len man hinh

cho HS thao luan ciing co noi dung bai

hgc:

Cau 1 Cho Al tir tir din du vao dung

djch hon hgp Cu(N03)2, AgN03,

Mg(N03)2, Fe(N03)3 thi thii tu cac ion

Cau 2 Hoa tan 20g hon hgp gom hai

kim loai Fe va Cu vao dung dich HCl

du Sau phan ung, co can dung dich

dugc 27,Ig chat ran The tich chat khi

thoat ra a dktc la

A 8,96lit B 4,48lit

C 2,241it D l,121it

Cau 3 Lan lugt cho timg kim loai Mg,

Ag, Fe va Cu (co so mol bang nhau),

tac dung vai lugng du dung dich

H2SO4 dac nong Khi phan ling hoan

toan thi the tich SO2 thoat ra it nhat

(trong ciing dk) la tir kim loai:

A Mg B Ag

C Fe D Cu

Hogt dgng 5

CUNG CO BAI VA BAI TAP VE NHA

HS quan sat theo luan cho ket qua

D HU'aNG D A N G I A I BAI TAP TRONG SGK

"Ag* ="AgNo, = 0 , 3 1 = 0,3 (mol)

Dat Upg = x(mol) -^ n^, = 2x(mol)

Ta co: 56x + 27.2x = 5,5 -> x = 0,05 (mol)

Al + 3Ag* -^ Al^* + 3Ag Chat ran thu dugc sau phan ung gom Ag, Fe

m = 108.0,3 + 56.0,05 = 35,2 (gam)

E TU" LIEU THAM K H A O

D I giai thich cac li tinh ca ban cua kim loai co the dua vao thuyet "khi electron''

va thuyet vitng ndng lugng

1 Thuyit "khielectron"

Thuyet "khi electron" cho rang mang tinh the kim loai a the ran va long bao gom dong thai cac nguyen tir da bi ion hoa, tiic la cac nguyen tir da bi tach mgt phan cac electron hoa tri cua minh Cac electron hoa tri lien ket yeu vai cac hat nhan nguyen tir, trong do c6 mgt so chuyen dgng tu do de dang trong toan khoi kim loai, chuyen dgng hon loan nhu cac phan tir khi Vi the co the coi nhu co khi electron chuyen dgng trong mang tinh the kim loai Kieu lien ket giiia "khi

electron" vai cac nguyen tir va ion kim loai ggi ia lien ket kim logi

Gidi thich: Bing thuyet "khi electron" c6 the giai thich dinh tinh cac tinh chit li

hgc dac trung cua kim loai:

• Kim loai co anh kim vi "khi electron" trong cau triic tinh the kim loai tao ra cho kim loai kha nang phan chieu manh cac biic xa nhin thiy Mgt s6 kim loai CO mau vi chi hap thu mgt so biic xa va phan chieu mgt so biic xa nhin thay khac Dong co mau do vi no da hap thu cac biic xa ciing mau xanh

• Kim loai din dien tit vi "khi electron"chuyln dgng tir hSn loan sang co huong khi lap mgt hieu dien thi a hai dau day din Dun nong, do dan dien giam vi tang su chuyin dgng hon loan cua "khi electron" va tang su dao dgng cua nguyen tir hay ion kim loai lam can su chuyen dgng co huong cua electron

• Kim loai din nhiet tit vi khi tang nhiet do a mgt chS thi a do nguyen tir va ion kim loai dao dgng manh, truyen sang cac electron tu do, roi tir cac electron tu do truyen sang cac nguyen tir va cac ion kim loai lan can Cir the dao dgng cua cac nguyen tir va cac ion trong toan khoi kim loai dugc tang cuong va trang thai nhiet cua khoi kim loai dugc thang bang nhanh chong

• Kim loai co tinh deo la nha "khi electron" lien kit cac tieu phan (nguyen tir

va ion kim loai) trong tinh the va chiing co the bi xe dich do chiu tac dung ciia mgt lire ca hgc

Han chi cua thuylt "khi electron" la khong thi giai thich dugc mgt each triet dl miic do khac nhau vl 4 tinh chit li hgc dac trung ciia kim loai va khong the giai thich dugc cac tinh chat li hgc rieng ciia moi kim loai

2 Thuyit viing ndng luffng

Thuylt vimg nang lugng dua tren co sa phuong phap obitan phan tir (MO), la thuylt hien dai co thi khic phuc nhimg thilu sot cua thuylt "khi electron" ve cau triic kim loai

Theo thuylt nay, kim loai rin hay long c6 ciu tnic tinh thi, nut mang la ion duang Cac obitan nguyen tir (AO) hoa tri cua cac kim loai dugc t l hgp thanh cac MO chung cho toan bg tinh thi Trong su hinh thanh phan tir hai nguyen tir, sir xen phu giiia 2 AO lien kit lam xuit hien 2 MO Khi mgt nguyen tir thii

ba dugc kit hgp vao phan tir nay thi co su hinh thanh 3 MO Nhu vay neu tinh thi kim loai gIm N nguyen tir (N = 6,023.10^^) thi su xen phii ciia N AO se cho ta N (MO) M6i MO ung vai mgt trang thai nang lugng xac dinh Vi so N rit lan, nen N trang thai xich lai gin nhau tao nen viing nang lugng Su khac nhau vl nang lugng ciia cac trang thai trong giai ban mgt vimg la vo ciing nho

be, chi bing khoang 10"^^ eV nen co thi coi viing nang lugng nhu mgt vach nang lugng lien tuc Cac MO cua viing nang lugng tuong tu nhu cac MO bat dinh xir khap tinh the kim loai

27

Hinh 5.1 cho thay sa do hinh thanh cac miic nang lugng (tao ra vimg nang lugng khi tang s6 nguyen tir tuong tac)

E

1 2 4 8 16 N

Sa'db hinh th^nh cac vung nang lugng khi tang lien tuc

so nguyen tir trong tinh the kim loai

Su dien cac electron vao cac MO trong viing nang lugng xay ra theo thii tu nang lugng tang dan va theo nguyen li Pauli (moi MO toi da 2e co spin doi song) Vay neu tinh the gom N nguyen tir, cac viing nang lugng hinh thanh do sir xen phu cac AO s, p, d, f se chiia tii da 2N (vimg s), 6N (vimg p), ION (viing d) va 14N (viing f) electron Tuy thuoc vao cau hinh electron ciia nguyen tir va tinh doi xiing cua mang tinh the, viing chiia electron dam bao cho su lien

ket ggi la viing hod tri (viing chiia electron hoa tri) va viing trong tren viing hoa

tn ggi la viing ddn Neu viing hoa tri va viing dan khong xen phii nhau thi co mgt khoang gian doan ve nang lugng ggi la vung cdm 0 cac tinh the kim loai

thuang xay ra sir xen phu nhau cua viing hoa tri va vimg dan Trong chat ban dan viing cam co chieu rgng AE = 0,1 - 3,0 eV va trong chit dien moi (each dien) CO AE > 3,0 eV (xem hinh 5.2)

Cac electron hoa tri chuyen dgng tren cac MO chung cho toan bg tinh thi nen

CO tac dung rang buoc cac ion duong kim loai thanh mgt khoi

Gidi thich tinh chdt vdt li ciia kim logi:

• Theo thuyet vimg nang lugng, vi cac electron hoa tri chuyen dgng tren cac

MO cua viing hoa tri tao ra nhiing dam may electron da lam tang kha nang phan chieu va giam kha nang hap thu cac biic xa nhin thay ma kim loai co

anh kim Ciing vi co cac electron hoa tri chuyen dgng tren cac MO chung

ma lam cho toan bg tinh the luon luon lien ket vai ion duong thanh mgt khdi

ddu chiu dugc tac dung cua luc ca hgc ma kim loai co tinh deo

Tinh dan dien va dan nhiet tit cua kim loai dugc giai thich nhu sau: cac kim loai dan dien tit nhit thuoc nhomTA va IB Nguyen tir ciia cac kim loai nay chi CO 1 electron hoa tri s nen viing nang lugng ciia tinh the kim loai moi chira 1/2 s l electron tii da Trong tinh thi chiia N nguyen tir thi co N (AGs) ciia lap ngoai ciing xen phii tao ra N (MO), lap thanh vimg nang lugng gIm

N mire Vi co N electron hoa tri nen so electron chi chiem N/2 miic (moi mire 2 electron) N/2 miic bi electron chiem tao thanh vimg hoa tri N/2 miic con lai dang tring tao thanh viing dan Cac miic bi chiem nam gan true tiep vai cac mire tring tao co hoi cho cac electron c6 the chuyen dich dugc duoi tac dung ciia dien truong Do do kim loai nhom IA va IB dan dien tot

Trong tinh thi kim loai nhom IIA va IIB su xen phii ciia cac AOs ciia N nguyen tir ciing tao ra vimg N mire Do moi nguyen tir co 2 electron s nen viing nay phai dugc xIp 2N electron nghTa la viing hoa tri da dirge dien dii Tuy nhien, cac AOp ben ngoai ciing xen phii nhau thanh cac MO tao ra viing nang lugng tring p vai 3N mire (viing dan) Hai vimg hoa tri s va vimg dan p xen phii nhau tao thanh viing lai hoa sp Cac electron cung chuyen dich true tilp theo cac mire ciia viing lai hoa sp khi co tac dung cua dien truong

Tuong tu vai cac nguyen t l chuyen tiep d (chang ban Cr 3d 4s ) Neu tinh thi gIm N nguyen tir thi kit qua ciia su xen phu eiia cac AOs lap ngoai ciing tao ra vimg s gIm N mire va cua AOd lap sat ngoai cimg tao ra vimg d gIm 5N miic Su xen phii cua 2 vimg s va d tao ra viing lai hoa ds gom 6N miic.Nguyen tir cua nguyen t l chuyen tiep nhu Cr chi co 6 electron hoa tri nen tinh thi N nguyen tir chi co 6N electron hoa tri va chi dien vao 6N/2 = 3N mire Vimg lai hoa ds con 3N mire trong nen kim loai chuyen tiep dan dien tot

Cac kim loai dan nhiet tit nho kha nang di chuyen tu do ciia cac electron hoa tri trong tinh thi va truyin nang lugng tir phin nong hon sang phan lanh ban Khi dun nong, dao dgng ciia cac nguyen tir tai cho bi dun nong tra nen manh ban, gay kho khan cho su chuyin dgng co huang ciia electron hoa tri

tu do theo chilu ciia dien truang hay tir phin nong den phin lanh Do do tinh din dien va dan nhiet cua kim loai giam khi nhiet do tang

Thuc nghiem cho thiy khoang 1 electron trong so cac electron hoa tri ciia nguyen tir kim loai gay ra tinh dan dien va dan nhiet, so electron hoa tri con

29

lai tham gia tao lien ket cong hoa tri bSn giua cac nguyen tu kim loai Do do phan lan cac kim loai chuyen tiep co khoi lugng rieng, nhiet do nong chay, nhiet do soi va do cung Ion horn nhieu so vod cac kim loai khong chuydn tigp

Hoac Viing

d a n Vung hoa tri Kim loai

Vung d a n

Cac viing phii len

n h a u

v^'ung d a n

Vung cam r(

Vung hoa tri Vat each dien

n g

Viing d a n

i Viing cam h e p Viing hoa tri

• Khai niem ve hgp kim

• Tinh chat va ling dung cua hgp kim trong cac nghanh kinh tl quoc dan

3 Tinh cam, thai do

Co y thirc bao ve kim loai, chong an mon kim loai do hieu ro nguyen nhan va tac hai ciia hien tugng an mon kim loai

B C H U A N B! C U A GV VA HS

• GV: Bang phu ve hinh bilu dien thi nghiem an mon dien hoa va ca che cua

su an mon dien hoa hgc dii vai sit (hoac thi nghiem mo phong)

• HS: On lai bai cii va xem truac bai hgp kim

C TI^N TRiNH DAY- HOC

Hogt dgng cua GV Hogt dgng cua HS

Hogt dgng 1

I KHAI NIEM

GV chieu len man hinh tranh anh hoac

cac mau vat sau va giai thieu:

- Manh duyra la hgp kim ciia Al, Cu,

Mn, Mg

- Thanh thep (1 mieng gang), la hgp

kim cua Fe, C

- Day chuyen, nhan, bong tai lam bang

vang tay la hgp kim ciia Au, Cu, Ag

Yeu ciu HS cho bilt: Thanh phan cua

cac hgp kim tren co gi giong va khac

nhau

Tir do neu khai niem hgp kim

GV bo sung:

- Hgp kim khong phai la hon hgp

thong thuang thu dugc khi trgn 2 chat

voi nhau Ma la san pham thu dugc khi

nung chay h6n hgp kim loai vai kim

loai hay kim loai vai phi kim

- Hgp kim co cau tao tinh thi va dugc

chia lam cac loai:

+ Tinh thi hon hgp

+ Tinh thi dung dich ran

+ Tinh thi hgp chit hoa hgc

HS quan sat thao luan va nhan xet:

Giong nhau: D I U C6 thanh phan la kim loai

Khac nhau: Ngoai kim loai do con co kim loai khac hay phi kim trong hgp kim

Khdi niim:

Hgp kim la vat lieu kim loai co chiia

them mgt hay nhilu nguyen to Nguyen

t l trong hgp kim co the la kim loai hoac phi kim

31

Hogt dgng cua GV Hogt dgng cua HS

GV giai thieu:

- Tinh chat hoa hgc ciia hgp kim thi

thuang CO tinh chat cua cac don chit

cau tao nen hgp kim

Vi du: Hgp kim Cu-Zn thi co tinh chit

cua Cu va tinh chit cua Zn

- Tinh chat vat li: Co nhilu thay doi so

vai tinh chat ciia cac don chat

GV neu cae vi du sau ve don chat va

hgp chat

- Vang 99,99% dep nhjimg mIm,

nhirng do diing bang vang 99,99% de

meo va mon De khac phuc nhirng

nhugc diem do nguai ta diing hgp kim

ciia vang vai Ag, Cu de lam do trang

sirp va diic tien

- Do dan dien ciia Cu rat tot (diing thii

2 sau Ag) Do dan dien cua dong giam

nhanh neu co lan tap chat Do vay, day

dien la dong co tinh khilt vai 99,99%

- Nhiet do nong chay cua Sn (232°C)

Nhiet do nong chay ciia Pb (327.4°C)

-^ Nhiet do nong chay cua hgp kim

Sn-Pb(thilchan)la210°C;

Yeu cau HS nhan xet su bien doi tinh

chat vat li ciia hgp kim

Hogt dgng 2

II TINH CHAT

HS nghe giang va ghi bai

HS thao luan va nhan xet

- Hgp kim thuang ciing hon cac kim loai thanh phan

- Do dan dien ciia hgp kim giam nhieu

so vai kim loai don chat

- Nhiet do nong chay ciia hgp kim giam

so vai kim loai don chat

Hogt dgng ciia GV Hogt dgng cua HS

Hogt dgng 3

III iTNG DUNG

GV Chieu len man hinh tranh, hinh anh

bang powerpoint giai thieu vl nhiing

ling dung ciia hgp kim

HS ghi bai

- Thep khong gi (thep inox): Fe(74%)-Ni(8%)-Cr(18%): Cbl tao dung cu y te, nha bep

- Thep Mn rat ben, chiu dugc va dap manh, dimg de che tao duong ray xe lira, may nghien da

- Thep W-Mo-Cr rat cimg dii a nhiet

do cao, diing che tao luoi dao cat ggi kim loai cho may tien, may phay

- Duyra hgp kim Al(95%), Cu(4%), Mn-Mg-Si(l%) Duyra nhe gin nhu nhom nhung lai rat cimg, cimg gip 4 lan nhom tire gan bang thep ma lai nhe bang 1/3 thep Duyra ben Dimg lam vat lieu che tao may bay, 6 to

Hogt dgng 4

CUNG CO BAI VA BAI TAP VE NHA

GV chieu cac bai tap sau len man hinh

cho HS thao luan ciing co noi dung bai

hgc:

Bai 1 Cho hgp kim gom ba kim loai A,

'B, C CO khoi lugng 2,17g tac dung hit

vai dung dich HCl tao ra 1,68lit khi H?

(dktc) jChoi lugng muoi clorua trong

dung dich sau phan img la

Hogt dgng cua GV

Bai 2 Cho 2,55g hgp kim dang bgt X

gom Al, Fe, Cu phan img vai dung did

NaOH du, thu dugc l,681it H2 (dktc),

dung dich B va chit rin C Cho C tac

dung vai HCl du sinh ra 0,2241it khi H2

(dktc), dung dich E va chat ran F

Thanh phan phan tram ve khoi lugng

cua AI, Fe, Cu trong hgp kim

Bai tap ve nha: 1, 2, 3, 4, (SGK)

D HU'ONG D A N G I A I B A I TAP TRONG SGK

2 Phuang trinh hoa hgc:

Ag + 2HNO3 -^ AgNOs + NO2 + H2O

AgN03 + HCl ^ AgCI^ + HNO3 Theo (1) va (2) ta c6 UAg = 0,00277 (mol)

- %A^J''-':''^'\m% = 59,,3%

(1) (2)

22,4 = 0,04(mol)

Ggi X, y la so mol cua Zn va Fe Ta co he phuong trinh:

|65x + 56y = 2,33 Jx = 0,01 [x + y = 0,04 " ^ | y = 0,03

• Khai niem an mon va cac dang an mon chinh

• Cach bao ve cac do dung may moc bang kim loai, hgp kim

HS hiiu:

Ban chit ciia qua trinh an mon la qua trinh oxi hoa khir trong do kim loai bi oxi hoa thanh ion duong

2 KT nang

Van dung kiln thirc hiiu bilt vl pin dien hoa hgc dugc de giai thich hien tugng

an mon dien hoa hgc

3 Tinh cam, thai do

Co y thiic bao ve kim loai, chong am mon kim loai do hieu ro nguyen nhan va tac hai cua hien tugng an mon

C TltN TRiNH DAY- HOC

Hogt dgng 1

I KHAI NIEM

GV cho HS nghien cim SGK va yeu

cau HS neu

- Khai niem su an mon

- Ban chat ciia su an mon kim loai

GV giai thieu: Trong cugc song,

chiing ta quan sat thuang thay: Do

dung bang sat, thep sau mgt thofi

gian sir dung bi gi set, khi bi gi set

CO con la thep nira khong?

Tir do dan dat HS di den khai

niem:+ Ban chat cua sir an mon kim

loai

+ Cac dang an mon kim loai

HS nghien ciiu SGK va nhan xet

- Khdi niim: Su an mon kim loai la sir pha

buy kim loai hoac hgp kim do tac dung ciia cac chat trong moi truong xung quanh

- Bdn chdt ciia sir an mon kim loai: Kim

loai bi oxi hoa thanh ion duong

M - ^ M ne

Hogt dgng 2

II CAC DANG AN MON KIM LOAI

1 An mon hoa hoc

GV cho HS nghien cim SGK va yeu

cau HS neu:

- An mon hoa hgc la gi?

- Cho vi du ve: Su an mon hoa hgc

thuang xay ra a dau?

HS nghien cim SGK va nhan xet

An mdn hod hoc la qua trinh oxi hoa - khir,

trong do cac electron cua kim loai dugc chuyen true tiep den cac chat trong moi truang

- Thuang xay ra a: Lo dot, noi hai, chi tiet ciia dgng ca dot

- Dimg hop nhom dung xa phong, giim

Hogt dgng cua GV Hogt dgng cua HS

2 An mon dien hoa hoc

a) Khdi niim

GV lam thi nghiem: Nhiing thanh

kem va thanh dong khong tilp

vod nhau vao coc dung dung

H2SO4 loang N l i thanh kem

thanh dong bang day dan cho di

mgt von ke

Cho HS quan sat yeu ciu HS

- Neu hien tugng

- Giai thich

- Ket qua thi nghiem

xuc dich vai qua

GV nhan xet trong thi nghiem tren

thi Zn bi an mon theo kieu an mon

dien hoa hgc va tir do yeu cau HS

neu khai niem an mon dien hoa hgc

HS quan sat thi nghiem

- Hiin tugng: Kim von ke quay, chimg to

CO dong dien chay qua Thanh Zn bi mon dan, a thanh Cu co bgt khi thoat ra

+ 0 dien cue duong (catot), ion H ciia dung dich H2SO4 nhan electron bien thanh nguyen tir H roi thanh phan tir H2 thoat ra: 2H^ + 2e ^ H2t

Ket qua Circ am: thanh Zn

Zn -^ Zn^*+2e

Cue duong: thanh Cu 2H" + 2e^- Hjt Ket qua thanh Zn bi an mon

HS thao luan cho nhan xet:

An mdn dien hod la qua trinh oxi hoa

-khir, trong do kim loai bi an mon do tac dung cua dung dich chat dien li va tao nen dong electron chuyen dai tir cue am din cue duong

37

Hogt dgng cua GV Hogt dgng cua HS

GV bo sung: can phan biet an mon

hoa hgc va an mon dien hoa hgc:

An mon dien hoa hgc co tao ra dong

dien gian tiep qua day dan hoac

dung dich dien li

b) An mon diin hod cdc hop kim sdt trong khong khi dm

GV giai thieu:

- Trong khong khi am, tren be mat

cua sat luon c6 mgt lap nuac rat

mong da hoa tan O2 va khi CO2

trong khi quyen, tao thanh mgt

dung dich chat dien li

- s i t va cac tap chat (chii yeu la

cacbon) ciing tiep xiic vai dung

dich do tao nen vo so pin rat nho

ma sat la anot (cue am) va cacbon

la catot (cue duong)

GV huong dan HS viet cac qua

trinh cho nhan electron a cac dien

cue va neu ket qua ciia su an mon

HS vilt cac qua trinh duai su dilu khien cua GV

2+

- Tai anot, sat bi oxi hoa thanh ion Fe

Fe -^ Fe + 2e Cac electron dugc giai phong chuyen dich den catot

- Tai viing catot, O2 hoa tan trong nuac bi khir thanh ion hidroxit:

O2 + 2H2O + 4e -> 40H^

- Kit qua ciia qua trinh Cue am: tinh the Fe Circ duong: tinh the C

Fe -^ Fe^^+2e 02+2H20+4e^ 40H^

Hogt dgng cda GV Hogt dgng cua HS

GV bo sung: Khi tan vao dung dich

dien li thi ion Fe c6 them cac qua

trinh tao gi sit:

Fe^^ + 20H" -> Fe(0H)2

4Fe(OH)2+02(kk)+2H20 ->

4Fe(OH)3 Fe(0H)3 P'''"^"^ )Fe203.xH20

Gisat

c) Dieu kiin xay ra sif an mon diin

GV chuyen tiep tir: Thi nghiem

thanh Cu va thanh Zn trong H2SO4

va sir mo ta qua trinh an mon gang

thep Yeu cau HS thao luan duai sir

dieu khien cua GV de neu dieu kien

ciia su an mon dien hoa hgc

GV luu y cho HS: Thieu mgt trong

ba dieu kien tren se khong xay ra su

an mon dien hoa

GV giai thieu cau tao cua pin dien

hoa tuan theo dieu kien an mon

dien hoa hoc

Vat bang gang, thep (hgp kim ciia Fe, C, )

bi an mon theo kieu dien hoa

hod hgc

HS thao luan cho ket qua

- Cac dien cue phai khac chat nhau, c6 the

la cap 2 kim loai khac nhau hoac cap kim loai vod phi kim

- Cac dien cue phai tiep xuc true tiep hoac gian tiep vai nhau qua day dan

- Cac dien cue cimg tiep xuc vai dung dich chat dien li

Hogt dgng 3

III CHONG AN MON KIM LOAI

GV neu tac hai ciia su an mon dien

hoa (hay cho HS dgc SGK)

GV neu nguyen tac cua phuong

phap chong an mon dien hoa la

ngan can 1 trong 3 dieu kien an

mon dien hoa hgc yeu cau HS de

HS thao luan cho cac phuang phap:

- Ngan cho vat lieu tiep xuc ciing voi 1 dung dich dien li

39

Hogt dgng cua GV

xuat cac phuang phap chong an

mon

Hogt dgng cua HS

- Khong cho 2 vat lieu tiep xuc vai nhau

- Dimg vat lieu khac dl thay the vat lieu can bao ve

L PhiroTig phap bao ve be mat

GV chia nhom HS:

Yeu cau HS nhom 1: Neu cac HS nhom 1 thao luan cho kit qua:

phuang phap bao ve bl mat, cho vi Dimg nhung chit bin vimg doi vai moi

truang de phii ngoai mat nhung do vat bang kim loai nhu boi dau ma, son, ma, trang men,

Vi du: Sat tay la sat dugc trang thiec, ton la

sat dugc trang kem Cac do vat bang sat thuong dugc ma niken hay crom

2 PhiroTig phap dien hoa

du minh hoa

Yeu cau HS nhom 2: Neu cac

phuang phap dien boa de bao ve

kim loai, cho vi du minh hoa

GV bo sung: ngoai 2 phuang phap

tren thi nguai ta con dimg:

- Chat kim ham (chat ire che) lam

cham qua trinh an mon

- Sir dung cac vat lieu khong an

mon nhu inox de thay the

HS nhom 2 thao luan cho ket qua:

Noi kim loai can bao ve vai mgt kim loai boat dgng hon de tao thanh pin dien hoa va kim loai boat dgng ban bi an mon, kim loai kia dugc bao ve

Vi du: De bao ve vo tau bien lam bang thep

va vo tau (phan chim duai nuac), ong thep dan nuac, dan dau, dan khi dot a duai dit, nguai ta lap vao mat ngoai cua thep nhirng khoi kem Ket qua la kem bi nuac bien hay

dung dich chat dien li a trong dat an mon

thay cho thep