1BI 1: CAN BANG LONG - LONG HE HAI CAU T

I. MUC CH.

Khao sat o tan cua he 2 chat long hoa tan han che vao nhau, t o thiet lapgian o pha nhiet o - thanh phan cua he.

II. C S LY THUYET VA NGUYEN TAC.

Xet he phenol - nc nhiet o co nh.

Khi them dan phenol vao nc th luc au phenol tan hoan toan trong nc, hetao thanh 1 pha duy nhat (ong the). Neu tiep tuc cho phenol vao ti mot nong o naoo, no khong tan na va he phan ra 2 lp (pha): lp phenol bao hoa nc ( di) valp nc bao hoa phenol (tren). Hai lp chat long nay c goi la lien hp nhau, khilac manh th hon hp tron lan vao nhau gay uc.

moi nhiet o, o hoa tan cua phenol trong nc va cua nc trong phenol cogia tr xac nh. Khi nhiet o tang, o tan lan tang. o th bieu dien anh hng cuanhiet o en o tan lan (bieu o nhiet o thanh phan) co dang nh hnh ve di ay:

Nhiet o K Tc

a b

Thanh phanHnh 1: Gian o nhiet o - thanh phan

aK va Kb lan lt bieu dien anh hng cua phenol trong nc (lp nc) va cuanc trong phenol (lp phenol).

K la iem hoa tan ti han, o thanh phan cua 2 pha bang nhau.

Tc goi la nhiet o hoa tan ti han. ng cong aKb chia bieu o thanh hai mien,mien trong gach cheo ng vi he d the (2 pha); mien ngoai he ong the.

T

m100%H2O 100%phenol

2Co the thiet lap bieu o nhiet o thanh phan bang 2 cach:

1. Phng phap ang nhiet.

Gi nhiet o cua he khong oi, thay oi thanh phan cua he (chang han them danphenol vao nc). Xac nh iem he chuyen t ong the sang d the va ngc lai.

Lac manh lo ng hai chat long nay roi ngam trong bnh ieu nhiet a co nhnhiet o, cho ti khi phan hoan toan thanh 2 pha (lp). Sau o phan tch nh lng 2lp nay.

2. Phng phap a nhiet.

Vi hon hp co thanh phan m chang han (he van uc), tang dan nhiet o en khihon hp tr thanh trong. Nhiet o tiep tuc tang, hon hp van trong. Vay can c vaonhiet o bat au trong hay bat au uc e xac nh iem b.

Lam th nghiem vi nhng hon hp co thanh phan khac nhau se xac nh cng cong aKb.

III. Dng c - ha cht

1. Dng c:

- ng nghim: 11 ng- Buret: 1 ci- Nhit k 100oC a khuy: 3 3 ci- Bp in: 1 ci- Ni un: 1 ci- Beccher 250: 2 ci

2. Ha cht:- Phenol- Nc ct

IV. THC NGHIEM

Cach tien hanh- Cho lo ng Phenol vao bnh ieu nhiet cho Phenol chay ra (nhiet o khoang

50oC). Tuyet oi khong un trc tiep phenol tren bep. Sau o nh lng khoang gia trPhenol can dung roi cho ra becher 50ml.

- Pha cac hon hp vao 11 ong nghiem theo bang so lieu sau:

3Ong 1 2 3 4 5 6 7 8 9 10 11Phenol 0,6 0,9 1,2 1,5 1,8 2,1 2,4 2,7 3,0 3,3 3,6H2O 5,4 5,1 4,8 4,5 4,2 3,9 3,6 3,3 3,0 2,7 2,4

- Cho ua khuay va nhiet ke lan lt vao cac ong nghiem.

- Nhung ong nghiem vao coc nc nong (coc nc khoang 800C a at san trenni un cch thy). Quan sat s thay oi nhiet o va s bien oi cua hon hp. Khi honhp sap trong phai cho nhiet o tang rat cham (bang cach nhac ong nghiem ra khoi cocnc nong) va khuay manh hn.

- Ghi nhiet o bat au trong. Sau o cho nhiet o ha t t (bang cach nhac ongnghiem ra khoi coc, tiep tuc khuay). Ghi nhiet o luc bat au uc. Hai nhiet o nayphai chenh nhau khong qua 0,50C.

Thc hien tren moi ong nghiem 3 lan lay gia tr nhiet o trung bnh.

V. KET QUA

1. Ket qua tho

Lap bang ghi cac gia tr nhan c cho 11 ong nghiem.

2. Ket qua tnh

- Ve o th nhiet o thanh phan khoi lng cua he phenol nc.- Xac nh nhiet o ti han va thanh phan hoa tan ti han cua he.

V. CAU HOI.

1. Bai th nghiem a c thc hien theo phng phap ang nhiet hay a nhiet? Hayphan tch s la chon qua trnh thc hien ?

2. Cho biet cac ac trng cua he (thanh phan va nhiet o ti han) co y ngha nh thenao?

3. Neu trong qua trnh un nong he van gi trang thai phan lp th qua trnh dien bient d the sang ong the se nh the nao?

4BI 2: CAN BANG LONG RAN

I. MUC CH:

Lam quen vi phng phap phan tch nhiet va thiet lap gian o nhiet o -thanh phan cua he hai cau t ket tinh khong tao hp chat hoa hoc va dung dch ran.

II. C S LY THUYET VA NGUYEN TAC:

Phng phap phan tch nhiet at tren c s nghien cu s thay oi nhiet o cuahe nguoi dan hoac nong dan theo thi gian.

ap suat nhat nh, nhiet o ket tinh cua mot chat nguyen chat co gia tr khongoi va gi nguyen trong suot qua trnh ket tinh. oi vi dung dch, nhiet o bat au kettinh phu thuoc thanh phan dung dch (thanh phan khac nhau nhiet o bat au ket tinhkhac nhau) va trong qua trnh ket tinh cau t th nhat, nhiet o giam dan cho ti khixuat hien cau t th hai cung ket tinh th nhiet o gi nguyen tc (ng vi nhiet oeutecti) cho ti khi qua trnh ket tinh ket thuc. Sau o nhiet o tiep tuc giam.

Hnh 2: Gian o nhiet othi gian Gian o nhiet othanh phan

Tren hnh ng nguoi (1) va (5) ng vi A, B nguyen chat. ng (2) va (4)ng vi hon hp co %B tang dan. ng (3) ng vi hon hp co thanh phan bang ungthanh phan eutecti.

Tren ng (1) va (5) cac oan thang nam ngang ng vi qua trnh ket tinh A vaB nguyen chat.

Nhi

et

o

Nhi

et

o

Thi gian

a

bc

d

e cb

e

Ea

A

B

C

D

1 2 3 4 5 1 2 3 4 5

dc

5Tren ng (2), (3), (4) oan nam ngang b, e, c ng vi qua trnh ket tinheutecti, con cac iem b, c ng vi iem bat au ket tinh 1 cat t nao o (cac hon hp(2), (4)) nhng iem nay xac nh de dang v o o doc cua ng bieu dien thay oido toc giam nhiet o trc va trong khi ket tinh khong giong nhau. Trong thc nghiemviec xac nh iem eutecti rat quan trong nhng lai rat kho. Thng dung phng phapTamman. Neu ieu kien nguoi lanh hoan toan nh nhau th o dai cua oan nam ngang(thi gian ket tinh) tren ng cong nguoi lanh se ty le vi lng eutecti. Nh vay neuat tren oan ad thanh phan va tren truc tung la o dai cac oan nam ngang cua ngnguoi lanh tng ng noi cac au mut lai, ta se c tam giac aId. nh I cua tam giacng vi thanh phan eutecti. Tam giac aId goi la tam giac Tamman.

III. Dng c - ha cht:

1. Dng c:

- ng nghim: 8 ng- Nhit k: 3 ci- a khuy: 3 ci- Becher 250ml: 3 ci

2. Ha cht:- Naphtalein- Diphenil - amin

IV. THC NGHIEM:

- Tien hanh chuan b 8 ong nghiem co thanh phan nh sau:

Ong 1 2 3 4 5 6 7 8Naphtalen 10 8 6 4,5 3 2,5 1 0Diphenil amin 0 2 4 5,5 7 7,5 9 10

Thc hanh

- Lan lt un cach thuy tng ong nghiem cho en khi hon hp chay long hoantoan.

- Lay ong ra lau kho ngoai ong.

- Theo doi s ha nhiet o theo thi gian, c sau 30 giay ghi nhiet o 1 lan.

- Lien tuc khuay nhe va eu tay cho ti khi tinh the au tien xuat hien th ngngkhuay va ghi nhiet o nay.

6- e kiem tra o bat au ket tinh ta nhung ong nghiem tr lai cho hon hp chaylong va lam lai t au th nghiem).

- Tiep tuc theo doi (khong khuay) va ghi nhiet o hon hp nguoi dan, cho ti khihon hp hoan toan ong ac.

Chu y: Khi nhiet o ong nghiem nguoi en khoang 40oC th s dung ong baokhong kh ben ngoai ong nghiem va nhung vao vao coc ng nc lanh. Tiep tuc ghinhiet o cho en khi nhiet o giam xuong 30oC th ngng th nghiem.

V. KET QUA:

1. Ket qua tho ghi lai nhiet o cua hon hp trong ong nghiem tng thi iem.

2. Ket qua tinh

- Ve gian o nhiet o - thi gian. Xac nh nhiet o bat au ket tinh, nhiet o eutecti,thanh phan eutecti.

- Ve gian o nhiet o thanh phan cua he diphenilamin naphtalen, xac nh nhiet

o va thanh phan eutecti.

V. CAU HOI

1. Nhiet o eutecti la g? iem eutecti la g?

2. Dung quy tac pha, giai thch v sao trong qua trnh ket tinh cua chat nguyen chathoac hon hp eutecti th nhiet o khong oi con qua trnh ket tinh dung dch th nhieto giam dan?

3. Tai sao nhiet o moi trng lam lanh phai thap hn nhiet o eutecti (te) neu nhieto moi trng ln hn te th se gay nen ieu g?

4. Gii thch gin ?

- in cc thnh phn vo tng vng ca gin .

- Gii thch cc ng trn gin .

BI 3: XAC NH BAC PHAN NGI. MUC CH:

7- Nghien cu anh hng cua nong o en van toc phan ng.- Xac nh bac cua phan ng phan huy Na2S2O3 trong moi trng acid bang thcnghiem.

II. C S LY THUYET:

Van toc phan ng c nh ngha la ai lng ac trng cho dien bien nhanhhay cham cua mot phan ng hoa hoc. Trong dung dch toc o phan ng trung bnh cuamot phan ng hoa hoc c xac nh bang bien thien nong o cua mot chat trong motn v thi gian:

t

CV=

+ Dau (-) neu C la bien thien nong o tac chat.+ Dau (+) neu C la bien thien nong o san pham.Khi t 0 th ty so tren dan ti gia tr gii han ta goi la toc o tc thi cua phan

ng tai thi iem khao sat.

dtdCV =

Vi phan ng tong quat:

aA + bB cC + dD (*)

Toc o tc thi cua phan ng tai mot thi iem t co the bieu th:

dtdC

da

dtdC

c

a

dtdC

ba

dtdCV DCBA ====

nh luat tac dung khoi lng cho biet anh hng cua nong o cac tac chat titoc o phan ng: Tai nhiet o xac nh, toc o phan ng moi thi iem ty le thuan vitch so nong o cac tac chat (vi so mu thch hp).

Bieu thc toan hoc cua nh luat tac dung khoi lng ap dung cho phan ng (*)co dang sau:

==

dtdCAV k.CAn .CBm

n+m: bac tong quat cua phan ng, m va n la cua cac so c xac nh bangthc nghiem ch khong the rut ra trc tiep t phng trnh phan ng.

k: c goi la hang so toc o, gia tr cua no ch phu thuoc ban chat cac chat tacdung va nhiet o va k con c goi la van toc rieng cua phan ng.

8Phan ng phan huy Na2S2O3 trong moi trng acid dien ra nh sau:

H2SO4 + Na2S2O3 Na2SO4 + H2SO3 + S

e o van toc phan ng ta phai xac nh t so C/t, trong o C la bien thiennong o san pham (ta chon lu hunh) trong khoang thi gian t, thng trong thcnghiem ngi ta co nh C va o t. Gia tr C phai nho e coi nh nong o cac chatcha thay oi ang ke va van toc xac nh c la van toc tc thi. Tuy nhien neu quanho th t cung rat nho, kho o.

Trong th nghiem nay ta co nh C bang cach ghi nhan thi gian t luc auphan ng en khi dung dch bat au chuyen sang uc. Nh vay khi van toc phan ngtang ch co t giam con nong o lu huynh sinh ra trong khoang thi gian t luc naocung nh nhau (o uc nh nhau).

e xac nh bac phan ng theo Na2S2O3 ta co nh nong o H2SO4, tang dannong o Na2S2O3. V d th nghiem 1, nong o Na2S2O3 la x, nong o H2SO4 la y, thigian t la t1, th nghiem 2, nong o Na2S2O3 la 2x, nong o H2SO4 la y, thi gian la t2,ta co:

=

=

11

t

CV kxmyn

22

t

CV = = k(2x)myn

Lp t s V1/V2 ta c :2m = t2/t1 lgt2/t1 = mlg2 m = 2lg

/lg 12 tt

e xac nh bac phan ng theo H2SO4, ta co nh nong o Na2S2O3 va tang dannong o acid H2SO4. Ket qua tnh n cung c thc hien tng t nh khi tnh m.

III. DNG C - HA CHT :1. Dng c:

- Bnh cu 1 c: 3 ci- ng nghim: 6 ci- Pipet 5ml: 1 ci- Pipet 10ml: 1 ci

2. Ha cht:- Dung dch Na2S2O3 0,1M

9- Dung dch H2SO4 0,4M- Nuc ct

IV. THC HANH:

1. Xac nh bac phan ng theo Na2S2O3:

Chun b 3 ng nghim ng acid v 3 bnh ay bang ng Na2S2O3 va H2O theobang sau:

Bnh cauSTT V(ml) H2SO4 0,4M V(ml) Na2S2O3 0,1M H2O

123

888

48

16

282416

- Cho acid vao cac ong nghiem theo bang so lieu.

- Ln lt cho H2O va Na2S2O3 0,1M vao 3 bnh cau.

- Chuan b ong ho bam giay.

- Lan lt cho phan ng tng cap ong nghiem va bnh cau nh sau:

o nhanh acid trong ong nghiem vao bnh cau.

Bam ong ho

Lac nhe bnh cau cho en khi va thay dung dch chuyen sang uc th bamong ho lan na.

oc t.

Lap lai moi th nghiem 2 lan na e lay gia tr trung bnh.

2. Xac nh bac phan ng theo H2SO4:

Lam tng t phan a vi lng acid va Na2S2O3 theo bang sau:

Bnh cauSTTV(ml) Na2S2O3 0,1M V(ml) H2SO4 0,4M H2O

10

123

888

48

16

282416

V. KT QU:

1. Kt qu th: ghi li cc gi tr t thu c.

2. Tnh gi tr bc phn ngVI. CU HI:

1. Trnh by khi nim v tc ca phn ng ha hc? Hng s tc ca mtphn ng.

2. Phn bit bc ca phn ng v phn t s ca phn ng?

3. Phn ng mt chiu bc nht, phn ng mt chiu bc hai l g?

11

BI 4: THUY PHAN ESTER BANG KIEM

I. MUC CH:

Khao sat toc o phan ng thuy phan ester trong moi trng kiem va anh hngcua nhiet o len hang so toc o cua phan ng.

II. LY THUYET:

Phan ng gia ester acetatetyl va NaOH xay ra nh sau:

CH3COOC2H5 + NaOH CH3COONa + C2H5OH. t = 0 a b 0 0 t a-x b-x x x

V ay la phan ng bac hai, nen toc o cua phan ng la:

x)x)(bk(adt

x)d(a=

kdtx)]x)(b[(a

dx=

hay

kdtdxxb

1xa

1b)(a

1=

+

Tch phan 2 ve ta c cktxbxa

lnba

1+=

ieu kien au t = 0, x = 0kt=

=

x)a(bx)b(a

lnba

1

ba

lnba

1C

Goi n0, nt, n la the tch NaOH con trong hon hp phan ng cac thi iem t = 0, t, .

Nong o NaOH cac thi iem se ty le vi cac the tch o. Con nong o ester thi iem au va thi iem t se ty le tng ng vi ( n0 - n ) va ( nt n).

Do oNaOH0

C = b = const . n0

este0C = a = const ( n0 n)

NaOHtC = b x = const. nt

estetC = a x = const[(n0 - n) (n0 nt)] = const (nt - n)

12

Vi const la hang so ty le theo bai nay ta co:

knn

n.

nnn

lnt.const.n

1

kt)n(nn)n(nn

lnconst.n

1

kt)const.nnconst(n

nconst(nconstnln

constn)nconst(n1

t

t

0

0

0t

t0

t0

t0.

00

=

=

=

)

Thay cac gia tr tren vao (1) ta c:

Anh hng cua nhiet o en hang so toc o. Phng trnh Arrhenius mo ta s phuthuoc cua toc o phan ng vao nhiet o co dang:

k = k0e-Ea/RT

k0: hang so c goi la tha so tan so hay tha so Arrhenius no khong phu thuocnhiet o.

Ea: nang lng hoat hoa cua phan ng.

Lay logarit 2 ve: lnk = lnk0 Ea/RT.

Theo phng trnh nay, hang so toc o phu thuoc tuyen tnh vi nghch ao cua

nhiet o phan ng.

=

21

a

1

2

T1

T1

RE

kk

ln

Goi k1, k2 la hang so toc cac nhiet o T1, T2 khi o:

Da vao (4) co the tm nang lng hoat hoa cua phan ng khi biet hang so toco 2 nhiet o khac nhau.

III. Dng c - ha cht:

1. Dng c:

- ng ong 250ml: 1 ci

- Elen 500ml: 2 ci

- Elen 100ml: 3 ci

- Pipet 10ml: 3 ci

- ng sinh hn: 1 ci

13

- Buret: 1 ci

- Beccher 100ml: 2 ci

- Nhit k 100oC: 2 ci

- Bnh iu nhit: 1 ci2. Ha cht:

- NaOH 0.01N- NaOH 0.01N chun- CH3COOC2H5 0.005N- HCl 0.01N- Phenolphtalein

IV. THC HANH:

1. Nhiet o phong

- Dung ong ong lay 150 ml dung dch NaOH 0,01N va 150 ml dung dch ester0,005N cho vao 2 bnh tam giac 500ml khac nhau, ay nut kn.

- Chuan b 3 bnh tam giac, moi bnh cha 12,5 ml dung dch 0,01N HCl.

- o nhanh dung dch NaOH vao ester (ghi thi iem t = 0), ay nut va lacmanh.

- Sau 5, 10, 20, 30, 40, 50 phut dung pipet hut 25ml hon hp phan ng cho vaobnh cha acid.

- nh chuan HCl d bang dung dch NaOH 0,01N ch th phenolphtalein 1%.

Sau 50 phut, un hoan lu cach thuy hon hp phan ng con tha en 700C vagi nhiet o o trong 30 phut. e nguoi ti nhiet o phong, sau o lay mau va chuano nh tren.

700C phan ng xay ra rat nhanh nen sau 30 phut co the coi phan ng a hoantat va d kien thu c khi chuan o NaOH lan nay ng vi thi iem t = .

2. Nhiet o bnh ieu nhiet:

Lng dung dch th nghiem giong nh tren. Ngam 2 bnh ng ester va NaOHtrong be ieu nhiet trong 20 phut, e at nhiet o t = 400C roi mi bat au cho phanng.

Tien hanh th nghiem tng t nh tren.

14

V. KET QUA.

a. Ket qua tho.

Lap bang ghi the tch NaOH dung chuan o HCl d.

b. Ket qua tnh.

- Tnh th tch NaOH c trong 25ml mu th.

- Tnh k trung bnh mi nhit .

- Tnh nng lng hot ha E ca phn ng

PHU LUCTm const trong bieu thc (2).

Dung dch NaOH co nong o ng lng N/100. Vay so ng lng NaOH cotrong 25 ml hon hp phan ng (hay trong n0 ml NaOH ) la:

So ng lng NaOH/25ml.Nong o NaOH trong mau th se la:

=

10001

1001

0 xxn 2500n

251000

)x10001

x1001

x(nC 000NaOH ==

0

10011000

n

Ma ta co: 00 .nconstC NaOH =

Vay2500

1.

2500 00

== constnconstn

V. CAU HOI:

1. Tai sao e lay d kien t phai un en 700C ? Khong lap ong sinh han hoan luc khong ?

2. Th nghiem t = 400C co can phai un hoan lu e lay d kien t khong ? Taisao?

3. Giai thch v sao theo tng thi gian phai cho 25ml dung dch phan ng vao dungdch acid HCl? Neu dung dch acid HCl o c lam lanh trc hay un nong len coc khong? V sao?

15

BI 5: XUC TAC ONG THE PHAN NG PHAN HUY H2O2

I. MUC CH:

Xac nh hang so toc o, chu ky ban huy va nang lng hoat hoa cua phan ngphan huy H2O2 vi ion Cu2+ la chat xuc tac.

II. C S LY THUYET VA NGUYEN TAC:

H2O2 t phan huy theo phan ng sau:

H2O2 H2O + 1/2O2Toc o cua phan ng tang nhanh khi co cac xuc tac Pt, muoi va oxyt cua cac kim

loai chuyen tiep

Phan ng tien hanh qua 2 giai oan:

1. HOOH O2 + 2H+ cham2.HOOH + 2H+ 2H2O nhanh 2H2O2 2H2O + O2

Toc o tong quat cua phan ng c xac nh bi giai oan 1 va do o phan ngxay ra theo bac 1.

III. Dng c - ha cht:

1. Dng c:

- Erlen 100ml: 5 ci

- Buret 25ml: 1 ci

- Pipet 10ml: 4 ci

- B iu nhit: 1 ci

2. Ha cht:

- H2O2

- H2SO4 10%

- CuSO4

- KMnO4 0.01N

16

IV. THC HANH.

- Tien hanh lay 20 ml dung dch H2O2 5% cho vao 1 bnh non va lay 10 ml dungdch CuSO4 0.05N cho vao 1 bnh non khac.

- at ca hai bnh non nay vao noi cung nhiet o (300C) trong 20 30 phut. Sauo tron dung dch H2O2 vao dung dch CuSO4 va e ngay hon hp nay vao noi.

- Lay 2 ml hon hp phan ng cho vao 1 bnh non a co san 2 ml H2SO4 10% roichuan o vi KMnO4 0,01N. Khi bat au nho giot KMnO4 au tien th ghi thi gian(bam th ke). o la thi iem t = 0. Ghi so ml KMnO4 a dung.

- Sau 5, 10, 15, 20 va 30 phut lai lay 2 ml mau th em chuan o.

Ket qua tnh

Tnh hang so toc o phan ng

CA la lng H2O2 ban au ng vi so ml KMnO4 a dung thi iem ban auCA Cx ng vi so ml KMnO4 a dung thi iem t, la lng H2O2 con lai sau

thi gian t.Tnh hang so toc o k moi thi iem va lay tr so trung bnh.

Lam lai th nghiem nhiet o t1 + 10 (400C). Tnh kt2 va nang lng hoat hoa cua phanng.

Tnh chu ky ban huy 1/2 t1 va t2

V. Cu hi:1. Th no l xc tc? Tc dng ca xc tc ng th v xc tc d th?

2. Chu k bn hy l g?3. Nng lng hot ha l g? Nhn xt g v gi tr nng lng hot ha tnh c t kt

qu lm th nghim?

17

BI 6: PHAN NG IOD HOA ACETON T XUC TAC.I. MUC CH:

Xac nh hang so toc o phan ng iod hoa aceton t xuc tac.

II. C S L THUYT:

Phan ng bac hai la phan ng co dang: A + B Sp (1)

2A Sp (2)ma bien thien cua moi chat trong qua trnh phan ng la ang ke.

Toc o phan ng c viet lan lt cho 2 phan ng (1) va( 2):

A2

BA

C

.CC

KdtdCV

KdtdCV

==

==

Bien thien nong o theo thi gian co dang nh ng vi trng hp phan ng xayra.

Phan ng xay ra trong moi trng ong the. Co hoac khong co chat xuc tac(nghch ao ng, xa phong hoa ester) ng vi trng hp co s t xuc tac (iod hoaaceton ). Toc o phan ng tai thi ien t nao o c xac nh bang o lech cua ngtiep tuyen vi ng bieu dien so vi truc thi gian, tai thi iem o. Trong trng hpth nhat, toc o giam dan va trong trng hp th hai, toc o tang dan theo thi gian.

Phan ng iod hoa aceton la phan ng bac hai co phng trnh phan ng nh sau:

CH3COCH3 + I2 CH3COCH2I + HI

Phan ng xay ra vi toc o ang ke trong moi trng acid hoac kiem. C chephan ng trong hai trng hp la khac nhau.

Trong moi trng kiem

Do ion OH- ket hp vi ion H+ rat manh, trong phan t aceton se co s chuyendch ien t ve oxy.

H3C C CH3

Do o ma H cua 1 trong 2 nhom metyl se tr nen linh ong va co xu hng tach ra.Phan ng xay ra nh sau: CH3COCH3 + OH- CH3-C=CH2 + H2O

18

Khi o se co 1 can bang gia aceton cetoenol va mi tao nen, toc o cua phanng nay cham (vi hang so toc o k1 be) amincetoenol se tng tac vi iod.

CH3 C = CH2 + I2 CH3COCH2I + I-

Giai oan nay xay ra nhanh (vi k2 >k1).

Trong moi trng acid

Khi co ion H+ ung hn la ion hydro-xoni H3O+) aceton tr nen hao H3O+, khi ophan ng xay ra nh sau:

CH3 -C-CH3 + H3O+ CH3 -C -CH3 + H2O

Hydro cua nhom metyl trong nhom anion cetoenol tr nen linh ong va lien ketvi cac phan t nc.

CH3-C-CH3 + H2O CH3 C=CH2 + H3O+

Phan ng nay xay ra cham ( vi hang so toc o k1 be). Nh vay giai oan naycua phan ng la s chuyen hoa toutomeceton va enol.

Trong giai oan 2, enol ket hp vi iod.

CH3 -C =CH2 + I2 + H2O CH3COCH2I + H3O+ + I-

Giai oan nay xay ra nhanh (vi k2>k1) .

Nh vay phan ng xay ra trong moi trng kiem va acid khac nhau cho trongmoi trng kiem co tao ion cetoenol, con trong moi trng acid co chuyen hoa toutomeceton va enol. Trong ca hai trng hp, Toc o phan ng c xac nh bang toc ocua giai oan cham tc giai oan au, ngha la qua k1. Trong moi trng acid. Ionhydro-xoni (H3O+) sinh ra moi luc mot nhieu, do o co ay u H3O+ cho phan ng, vthe phan ng trong moi trng acid thuoc loai phan ng t xuc tac.

Nh vay s ion hoa aceton trong moi trng acid co toc o la toc o cua giaioan th nhat tc la tao enol, phu thuoc vao nong o aceton va ion H3O+, ch khongphu thuoc vao nong o iod, phan ng la phan ng bac hai.

Goi so mol aceton va ion hydroxoni la a va b nong o cua chung la CA va CB, thi iem t, co x mol aceton tham gia phan ng va tao c x mol H3O+ va cung x molI- luc o.

19

VxbC

VxaC

B

A

+=

=

Theo phng trnh (1) ta se co:

))((2 xbxaVk

dtdV

+=

Tach bien so roi lay tch phan x = 0 luc t = 0 en x va t, ta se co:

( ) [ ] [ ]11

0 02

)(lg)(3,2

))((

= =

+

+=

=

+ nongdothoigian

bxaaxb

baVk

dtVk

xbxadxx

x

t

t

Lng aceton ban au xac nh bang cach cong lng ion H+, bang lng dungdch acid co nong o xac nh a lay; lng aceton a tien thu, theo o gram, lng ioda tham gia phan ng trong s iod hoa. Nh vay, trong tnh toan ch con mot bien so,c xac nh bang cach chuan o hon hp phan ng bang dung dch thiosunfat.

III. DNG C V HA CHT:1. Dng c:

- Bnh nh mc 250ml: 1 ci- Ni un: 1 ci- Bnh nn, nt nhm: 1 ci- Buret: 1 ci

2. Ha cht:

- Dung dch I2 0.1N trong KI 4%

- Dung dch HCl 1N

- Aceton

- Dung dch NaHCO3 0,1 N

- Dung dch Na2S2O3 chuan 0,1N

III. THC NGHIEM:

20

Cach tien hanhCho vao bnh nh mc 250ml, 25 ml dung dch iod 0,1N I2 trong dung dch KI

4%, 25 ml dung dch HCl 1N, them nc cat cho en khi con o 20 ml na th va envach, xong at bnh vao noi nc nau cach thuy khoang 300C .

Can tren can phan tch mot bnh non co nut nham c 50 ml trong o co san o 10 15ml nc cat, dung pipet lay o 1,5gram aceton (cho biet ty khoi aceton d = 0,792)cho vao bnh non. Can lai bnh non va lay lai hieu so 2 lan e biet khoi lng aceton alay.

at tiep bnh non ng dung dch aceton vao may ieu nhiet, i 10 15 phute cho chat long trong ca 2 bnh, bnh non va bnh nh mc bang nhau, ngha la 300C.o dung dch trong bnh non vao bnh nh mc trang vai lan bang nc cat, nc trangcung o vao bnh nh mc, them nc cat cho en vach cua bnh nh mc. Luc ayc xem la thi iem bat au phan ng (mat t phut luc o, trang khong quan trong vphan ng luc au xay ra rat cham).

Cac mau th c lay ra khoi bnh nh mc moi lan 25 ml c o vao 25 mldung dch NaHCO3 0,1 N roi chuan lng iod con d bang dung dch Na2S2O3 chuan0,1N co dung dch tinh bot lam ch th. Thi gian lay mau la luc au tc luc t = 0, sauo t = 10 , 15 , 30 , 45 , 60 , 90 tat ca 6 mau.

Tnh x bang cong thc: X = ( V0 Vt).C.10-3

Trong o V0 va Vt la the tch dung dch thiosulfat, a dung e chuan luc t = 0 valuc t, tnh bang ml, C nong o dung dch thiosulfat, lg/l.

Cach ghi so lieu va tnh toan

Khoi lng aceton m =

So mol aceton (trong 25 ml) a =

So mol ion H+ (trong 25 ml) b =

IV. CAU HOI:

1. Phn ng mt chiu bc hai l g? Nu lin h gia hng s tc bc hai vi thigian v nng .

2. Tnh thi gian can e iod hoa 50%, 80%, 90% aceton.3. Muon tnh nang lng hoat ong hoa cua phan ng iod hoa aceton, ngi ta co phai

lam them th nghiem g khong? Cach tien hanh th nghiem o nh the nao?

21

BI 7: HAP PHU TRONG DUNG DCH TREN BE MATCHAT HAP PHU RAN.

I. MUC CH:

Khao sat s hap phu acid acetic trong dung dch tren than hoat tnh va thiet lapcac ng ang nhiet hap phu tng ng.

II. C S LY THUYET VA NGUYEN TAC:

Danh t hap phu dung e mo ta hien tng trong o mot chat nao o ( di dangphan t, nguyen t hay ion) co khuynh hng tap trung, chat cha tren be mat phanchia pha nao o.

Trong trng hp chat hap phu ran, thng th chat co be mat rieng (tong dientch tren 1 gam chat ran) rat ln, co gia tr vao khoang 10 1000 m2/g. Cac chat happhu ran thng dung la: than hoat tnh, silicagel (SiO2), alumin (Al2O3), zeolit

Trong s hap phu cac chat tren be mat chat hap phu ran, nguyen nhan chu yeucua s hap phu la do nang lng d be mat tren ranh gii phan chia pha ran kh hayran long. Cac lc tng tac trong hap phu nay co the la lc Van der Waals (hap phuvat ly) hay cac lc gay nen do tng tac hoa hoc (hap phu hoa hoc) hay do ca hai loaitng tac tren cung tac dung.

Lng chat b hap phu tren be mat chat hap phu tuy thoc vao nhieu yeu to nh:

- Ban chat cua chat hap phu va chat b hap phu.

- Nong o cua chat tan.

- Nhiet o.

- Thc nghiem th nghiem nhiet o khong oi, ta co the o c so mol chat b hap

phu tren 1g chat hap phu ran ( ) cac nong o chat tan khac nhau( C ). ng bieudien - C goi la ng ang nhiet hap phu.

- Mot so phng trnh thc nghiem va ly thuyet a c s dung e bieu th cac

ng ang nhiet hap phu: Freundlich, Langmuir, BET

22

1. Phng trnh Freundlich

- ay la phng trnh thc nghiem, ap dung cho s hap phu chat kh hay chat hoa tantrong dung dch = K. C1/n.

- Trong o K va 1/n la nhng hang so khong co y ngha vat ly

- C la nong o dung dch hap phu at can bang

- Viet di dang logarit

log = 1/n logC + logK.

- Nh vay neu bieu th log theo logC, ta se c 1 ng thang co he so goc 1/n vatung o goc la logK.

- Phng trnh Freundlich thng thch hp khoang nong o (hay ap suat) trungbnh, v nong o thap thng ty le thuan vi C va nong o cao thng at ti1 tr so gii han va do o oc lap vi C.

2. Phng trng Langmuir:

- ay la phng trnh ly thuyet, ap dung cho hap phu n lp:

kCkC+

=

=

1

Trong o:

- : o che phu be mat- : so mol toi a chat b hap phu tren 1g chat ran sao cho cac phan t tao

thanh n lp.- k: hang so.

Co the viet lai phng trnh tren di dang:

+

=

kCC 1

Vay neu bieu th C/ ta c 1 ng thang co he so goc 1/ va tung o goc 1/k

T phng trnh Langmuir, co the xac nh c be mat rieng S0 cua chat hap phu theocong thc:

S0 = . N. A0Trong o N: so Avogadro = 6,023.1023.

23

A0: dien tch chiem cho trung bnh cua 1 phan t chat b hap phu( khi hap phu goi lan lp). Chang han vi CH3COOH, A0CH3COOH = 21 ( )2.III. Dng c - ha cht:

1. Dng c:

- Bnh nn: 6 ci

- Phu lc: 6 ci

- Buret 25ml: 1 ci

- Erlen 100ml: 5 ci

- Pipet 10ml: 3 ci

2. Ha cht:

- CH3COOH 0,2M

- Nc ct

- NaOH: 0.1N

- Phenolphtalein 1%

IV. THC HANH:

Cach tien hanh:

- Dung acid acetic CH3COOH 0,2M va nc cat, pha loang cac dung dch sautrong 6 bnh non co nut nham.

Bnh 1 2 3 4 5 6CH3COOH (ml) 50 40 30 20 10 5Nc cat (ml) 0 10 20 30 40 45

- Lac eu cac bnh va pha.

- Dung can phan tch can 6 mau than hoat tnh, moi mau 1g.

- Cho vao moi bnh cha dung dch CH3COOH mot mau than, ay nut lac manhtrong vai phut. e yen 10 phut roi lac manh vai phut. e yen 30 phut xong em loc.

24

- Ghi nhiet o th nghiem. Nc qua loc nh phan bang dung dch NaOH 0,1Nvi ch th phenolphtalein.

- Vi bnh 1, 2, 3 nh phan 3 lan, moi lan 5 ml nc qua loc.

- Vi bnh 4, 5 nh phan 3 lan, moi lan 10 ml nc qua loc.

- Vi bnh 6 nh phan 2 lan, moi lan 20 ml nc qua loc.

Lu y: than hoat tnh a dung em ra lai bang nc nong sau o loc, say roi cho vaochai e thu hoi lai.

IV. KET QUA:

1. Ket qua tho: lap thanh bang ghi cac gia tr thu c khi nh phan bang

dung dch NaOH

2. Ket qua tnh ghi theo bang

Bnh C0(mol/l) C(mol/l) logC (mol) Log() C/

a. Ve o th log theo logC. Suy ra hang so K, 1/n.

b. Ve o th C/ theo C. Suy ra K, .

c. Tnh be mat rieng S0 cua than hoat tnh m2/g.

(Dung phng phap bnh phng cc tieu e viet phng trnh cac ng bieu dien).

V. CAU HOI

1. Hay nhan xet bieu th s hap phu CH3COOH tren than hoat tnh bang ng angnhiet Freundlich hay Langmuir la thch hp nhat.

2. ng ang nhiet Freundlich co dang the nao khi 1/n =0, 1/n =1, 0

25

BI 8: X L LM SCH B MT KIM LOI BNG PHNG PHP HAHC V PHNG PHP IN HA

I. Mc ch:

Lm quen vi qu trnh x l b mt kim loi b nhiu g, du m bng cc phnng ha hc v phn ng in ha trn pilot in ha.

II.C S L THUYT:Trc khi m, vt m ngoi vic c tin hnh gia cng c kh c b mt bng

phng, th vic ty xa cc lp g, cc vt du m c c b mt sch cng l cngon quan trng khng th thiu.II.1. Ty du m:

C 2 loi du m bm trn b mt chi tit m:

- Loi th nht c ngun gc thc vt (du) v ng vt (m).- Loi th hai c ngun gc du m: du ha, du nhn, parafin,

Loi th nht nhm th nht d b x phng ha bi xt (NaOH), to thnh ccmui ca axt bo bc cao (x phng) tan c trong nc.

Cc loi du m nhm th hai khng b x phng ha, nhng chng d b nh habi cc cht kim v cng c th tch khi b mt chi tit.Ty thuc bn cht du m bm trn b mt chi tit ta c th p dng phng php tydu m khc nhau:

- Ty du m trong dung mi hu c.

- Ty du m trong dung dch kim v nh tng.

- Tu du m in ha.

- Ty du m siu m.

II.1.1. Ty du trong dung mi hu c:

Dung moi thng dung la trycloetylen C2HCl3, hoa tan tot nhieu loai chat beo,khong bat la, khong an mon kim loai (tr Al, Mg) nhng oc. Hi cua no nang gap 4lan khong kh, nen phai dung cac thiet b tay thch hp sao cho cho ng thao tac trencao va khong kh mat luon cho vao t tren xuong nen hi cua chung luon di thap.Tay bang cach nhung vat vao dung moi, tuy nhien tay trang thai hi ngng tu van tothn. Can dau m c loai bo sau khi chng. Tat ca c thc hien trong may kn, lienhoan.

26

Cac dung moi khac co the dung c la tetracloetylen C2Cl4, cacbon tetracloruaCCl4, tetracloetan C2H2Cl4, hexacloetan C2Cl6. Nhng iem can lu y khi dung cacdung moi nay: vat tay phai kho, v hi am hoac dung dich axit sot lai de tao vi dungmoi nhiet o cao thanh HCl gay an mon nhat la cac vat bang nhom va hp kim nhom.Sau khi tay, dung moi boc hi, e lai dau m hoa tan tren be mat tao thanh mang ratmong, can phai tay tiep chung trong dung dch kiem nong hoac tay ien hoa.

II.2. Ty du m trong dung dch kim nng:

Dau m bam tren be mat vat tay co 2 loai : loai co nguon goc t ong- thc vatva loai co nguon goc t khoang vat. Di tac dung cua kim loai kiem loai dau m tong- thc vat bien thanh xa phong de tan va glyxerin. V du:

( C17H35COO)3C3H5 + NaOH = 3C17H35COONa + C3H5(OH)3

stearin xa phong glyxerin

Xa phong (natri stearat) c sinh ra de tan trong nc, nhat la nc nong, vaen lt no, xa phong tr lai tay ra cho be mat kim loai.

Nong o NaOH ac qua de tao thanh mang oxit tren be mat thep, ong, hp kimdong, gay thu ong, con oi vi kim loai mau khac va vi kim loai nhe lai b an mon.

Na2SiO3 cho moi trng kiem yeu, co tac dung nhu hoa va c che an mon. Khithuy phan no tao thanh axit silixic keo, lam phan tan chat ran, cai thien kha nang tayra, ngan can khong cho chat ban ket tua tr lai tren be mat va c tay. Sau khi tayxong tren be mat kim loai co mang mong cua Na2SiO3 va Na3PO4, rat de ra sachtrong nc trung tnh hoac kiem yeu.

II.1.3. Ty du m in ha:

u iem: la tay rat nhanh, rat sach. Thng tay Catot, nhng oi khi cung tayAnot hoac tay lien hoan Catot Anot. Dung dch tay co thanh phan giong tay dau mhoa hoc nhng loang hn. C che cua tay dau m ien hoa la tach dau m tren be matthanh nhu tng trong dung dch nh viec thoat cac bot hydro tren Catot hoac oxi trenAnot. Khi nhung kim loai dnh dau m vao dung dch kiem, do tac dung cua sc cangbe mat, mang dau, m b nt v va co lai thanh giot nho. Di tac dung cua phan cc,o bam cua dau tren kim loai yeu i, cac giot dau cang co lai manh hn, ong thi tnhtham nc cua kim loai tang len. Cac bot kh nho tach khoi be mat kim loai se bam len

27

cac giot dau gan o, dan dan bot kh ln len om lay giot dau va cung tach khoi be matkim loai do sc ay thuy tnh.

Khi phan cc Catot, kh hydro thoat ra mot phan khuyech tan vao kim loai lamvat tay b don hydro. Mat khac do dung dch tch luy dan cac tap chat kim loai nh Zn,Pb, Sn, tuy ieu kien khong that thuan li chung cung co the phong ien phan nao vabam khong chac len vat tay Catot. V vay trc khi vt vat tay Catot ra nen oi chieudong ien e tay Anot trong khoang khac (c 30 giay). Khi o cac nguyen t hydro happhu tac dung vi cac nguyen t oxi, lam giam o gion hydro, ong thi mang kim loainoi tren cung b mat i. Tuy nhien neu tay Anot qua lau be mat b en do b oxi hoa,khong li. Luc o phai tay Catot tr lai e kh lp oxit. Phng phap nay goi la taylien hoan Catot Anot .

II.3. Ty g:

Tay g hoa hoc: Be mat kim loai en thng phu mot lp oxit day FeO, Fe2O3,Fe3O4 (goi la g) va cac hydrogenxit cua Fe2+ va Fe3+. Tay g hoa hoc cho sat thepthng dung dung dch axt loang H2SO4 hoac HCl hay hon hp cua chung. Khi taythng dien ra ong thi hai qua trnh : hoa tan oxit va hoa tan sat nen. HCl hoa tanoxit la chnh: H2SO4 hoa tan sat nen la chnh va cho kh hydrogen thoat ra lam bongmang oxit

Tay bang HCl nhanh hn, cho be mat trang hn nong o tot nhat la150 200g/lva tay nhiet o di 400C. Nong o va nhiet o cao hn se boc mui kho chu, sat nenb an mon nhanh.

Tay bang H2SO4 se nhanh neu tang nhiet o dung dch. Sau khi tay phai lamsach mun en tren mat vat tay. Tot nhat la dung nong o 80 - 120 g/l 50 -70 0C.

e han che hoa tan kim loai nen trong khi tay, ngay nay thng dung cac chatc che di dang phu gia cua dung dch. Cac chat nay c cac nha che tao cung capdi nhng ten goi a ma hoa nhng co hng dan s dung.

Tay g ien hoa: La tay g hoa hoc ong thi co s tham gia cua dong en, vattay co the la Catot hoac Anot.

III. THIT B V HA CHT:

28

III.1. Thit b:

Pilot in ha

III.2. Ha cht:

- Dung dch H2SO4 10%

- Dung dch Na2CO3 : 30g/l

- Dung dch NaOH: 30g/l

IV.THC HNH:1. Ty g ha hc:

- Chun b ming st (tn) b mt b g, kch thc (5 x 10)cm.- Lm sch s b lp g bng giy nhm.- Dng kp cho ming st vo b ty g ha hc.

Lu : tt c b mt vt ty cn phi ngp trong dung dch ty g, c th dng kp a ia li vt ty nh tc ng ca vic khuy.

- Quan st hin tng v theo di thi gian cho ti khi sch hon ton cc vt g.2. Ty g in ha:

- Chun b vt ty ging vi th nghim ty g ho hc.- Kim tra s tip xc ca cc in cc theo cc bc sau nh sau:

Ly u in cc anot (mu ) kp vo cc thanh dn c gn cc thanh in ccch.

Ly u in cc catot (mu en) kp ly mt ming kim loi bt k.

Nhng catot vo b ty g in ha. Bt cng tc ngun, quan st b mt catot v b mt cc in cc ch. Nu trn b

mt catot v cc in cc ch u thot ra cc bt kh khi cc in cc tipxc.

- Dng catot kp ly vt ty ri nhng vo b ty g in ha.- Bt cng tc ngun (chnh nc s 1 trn b iu chnh dng), quan st gi tr dng

in trn ampe k.- Quan st hin tng, sau 10 pht ly vt ty ra nh gi qu trnh ty g in ha.- Lm tng t vi 4 nc tip theo trn b iu chnh dng.

29

X l kt qu: Ghi nhn cc kt qu vo bng s liu.

So snh qu trnh ty g ha hc v qu trnh ty g in ha. Vt ty g xong dnglm mu cho th nghim ty du tip theo.

3. Tu du ha hc:

- Dng cy c thm du, sau qut ln ming st kim loi c ty g mt lpmng.

- Nhng mu thm du vo b ty du in ha.- Quan st, ch 10 pht ly mu ra. Nhn xt nh gi qu trnh ty.

4. Ty du in ha:

- Mu th nghim c chun b tng t nh th nghim ty du ha hc.- Kim tra s tip xc ca cc in cc, ghp ni catot anot tng t nh th nghim

ty g in ha.Lu : cc in cc ca b ty du in ha lm bng thp khng g.

- Bt cng tc ngun, iu chnh dng in nc s 1.

- Quan st, sau 10 pht ly vt ty ra nh gi qu trnh ty.- Tin hnh tng t vi 4 vt tt 4 nc tip theo ca b iu chnh dng.

V. KT QU:- Ghi nhn cc kt qu vo bng s liu.- So snh kt qu qu trnh ty du ha hc v qu trnh ty du in ha.

VI. CU HI:1. Mc ch qu trnh x l b mt.

2. Mc ch, c ch qu trnh ty g in ha?

3. Mc ch, c ch qu trnh ty du in ha?

4. Phn ng loi g st trong th nghim ty g?

5. Vit phng trnh phn ng thot kh trn b mt catot v anot ?

STT Ia(A/dm2) Ic(A/dm2) Thi gian (pht) nh gi b mt

30

31

BI 9: M NIKEL (Ni)I. Mc ch:

Tm hiu c ch qu trnh m Ni, ng dng nh lut Faraday kho st s phthuc hiu sut m Ni vo mt dng catot, tnh dy lp m thu c.II. C s l thuyt:

II.1. Tong quat qua trnh ma ien :

Tren anot xay ra qua trnh hoa tan kim loai anot :

M - ne Mn+

Tren catot, cation phong ien thanh nguyen t kim loai :

Mn+ + ne M

Thc ra qua trnh nay xay ra theo nhieu bc lien tiep nhau, bao gom nhieu giaioan noi tiep nhau.

Qua trnh catot co the gom cac bc sau :

1. Cation hydrat hoa Mn+.mH2O di chuyen t dung dch vao be mat catot.

+

Nguon MotChieu.

Anot Catot.

Lp ma

Catot.

+_

Ion (-)

Ion (+)

32

2. Cation mat vo hydrat (mH2O ), vao tiep xuc trc tiep vi be mat catot.

3. ien t (e ) t catot ien vao vanh ien t hoa tr cua cation, bien nothanh nguyen t kim loai trung hoa (phong ien ) dang hap phu.

4. Cac nguyen t kim loai nay hoac se tao thanh tinh the mi, hoac se thamgia nuoi ln mam tinh the a sinh ra trc o. Mam phat trien thanh tinhthe, tinh the ket tua thanh lp ma.

Toc o chung cua qua trnh catot nhanh hay cham la do toc o cham nhat cuamot trong cac bc tren quyet nh. Moi tr lc cua cac bc tren eu c the hien o phan cc catot (qua the catot c ), tc la ien the catot dch ve pha am hn motlng c so vi can bang :

c = cb

Trong o :

cb : ien the can bang cua catot , V.

: ien the phan cc cua catot (a co dong I ), V.

Gia phan cc catot (qua the catot ) va cau truc ket tua (lp ma ) co quan hechat che vi nhau : phan cc catot cang ln, tinh the cang nho mn.

II.2. Qua trnh catot va anot Nickel:

Nickel de b thu ong nen lp ma Ni co nhieu ac tnh tot, nhng hien tng dethu ong ay lai khong co li. Ta biet mat o dong ien khong cao lam, anot Nickelse tan ra thanh ion Ni2+. Neu mat o dong ien anot ln qua, ion Ni2+ sinh ra nhanh,khong kip khuyech tan ra khoi dung dch sat anot, khi a at en bao hoa no ong ketlai thanh man xop, lam cho ien tch hoat ong cua anot b hep lai mat o dien tchthc te tang len dan en ien the tang len: khi a at en ien the phong, ien cua IonOH- th tren anot bat au co kh Oxi thoat ra. Oxi mi sinh se oxi hoa Ni tao thanhmang oxit kn, chac tren be mat anot, va anot tr nen kho tan hoac khong tan c na.Anot thu ong se lam ngheo dan ion Ni2+ trong dung dch va H+ se co c hoi phongien tren catot lam giam hieu suat dong ien ma. V vay, e khac phuc hien tng thu

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ong anot, dung dch phai co ion Cl- (t NaCl hay NiCl2). Phong ien tren anot, ion Cl-

bien thanh kh Cl2, hoa tan nuc thanh axit hypoclorit co tac dung hoa tan mang thuong. Nong o ion Cl- phai gi ung quy nh, tha nhieu anot se tan qua manh, conthieu nhieu anot se b thu ong, anot lam viec bnh thng co mau sang, be mat nham:khi thu ong co mau vang nau, be mat giam, tren goc canh co oxi thoat ra.

Anot Nickel co nhieu loai va hnh dang khac nhau. Anot uc de tan nhng sinhnhieu mun, neu c u 900-1200oC se de tan hn. Anot ien phai rat tinh khietnhng tinh the to nen khi cha tan het cac tinh the a ri nhau ra thanh mun. Yeu cauanot phai co o tinh khiet cao (Ni>99%), nhng cang tinh khiet cang kho tan. e caithien tnh chat tan cho anot Ni cac hang che tao a a vao kim loai Ni cac chat chongthu ong, o la cac nguyen to vi lng O, C, S, Mn Cac chat nay c phan bo eutrong kim loai anot, co tac dung thuc ay qua trnh hoa tan ien hoa ong eu hn, tsinh mun hn, dung c vi mat o dong ien anot cao hn.

II.3. C s l thuyt nh gi lp m:

- Phng phap tnh trong lng kim loai cua lp ma:

m = . I . t. H/100 , (g)Trong o:

m: trong lng kim loai cua lp ma: ng lng ien hoa (g/Ah)H : hieu suat dong ien (%)t : thi gian ma (h)I : cng o dong ien (A)

- Phng phap xac nh hieu suat dong ien

+ Can phan tch xac nh khoi lng mau trc khi ma nickel (M)

+ Can phan tch xac nh khoi lng mau sau khi ma nickel Ms cac che okhao sat .

mthc te = Ms M (g)

+ Xac nh khoi lng nickel ket tua tren ien cc theo inh luat Faraay:

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m l thuyet = . I. t (g)

Trong o:

: ng lng ien hoa (g/Ah)t : thi gian ma (h)I : cng o dong ien (A)

Hieu suat dong ien khi ma nickel : = (mthc te/ m l thuyet ).100 (%)

- Phng phap anh gia lp ma theo cam quan:

Lp ma tot: co o phang, bong, ong eu ve tnh chat be mat..

Lp ma xau: b chay xam, khong ong eu, co cham kim, co gai..

- Phng phap tnh chieu day trung bnh cua lp ma:

Dtb = I . t . .H/ S. g.1000 (m)Trong o :

Dtb : chieu day trung bnh cua lp maI : cng o dong ien (A): ng lng ien hoa (g/Ah)t : thi gian ma (h)S :dien tch catot (dm2)H : hieu suat dong ien (%)g : trong lng rieng cua kim loai (g/cm3)

III. Dng c, ha cht :

III.1. Dng c :

- B m Ni bng trn pilot in ha.

- Cn phn tch 4 s.

IV.2. Ha cht:

- Dung dch NiSO4 : 250 g/l- Dung dch NiCl2 : 60 g/l- Dung dch H3PO3 : 45 g/l.

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- Dung dch phu gia levelling:1,5ml/lit- Dung dch phu gia bong: 1,5ml/lit- Vat lam Catot co dien tch 1.0 dm2

IV. Thc hnh:Th nghim c tin hnh trn pilot in ha theo cc bc sau:- Kim tra s tip xc ca cc in cc.

- Chun b vt m, vt m l ming st mng c tng din tch b mt 1.0 dm2.

- X l b mt kim loi: loi s b lp g bng giy nhm, ty sch cc lp g, du mbm trn b mt kim loi trong cc b ty g ha hc, ty g in ha, ty du ha hcv ty du n ha.

- Cho vt m c lm sch vo b trung ha khong 1 pht.

- Ly vt m ra, ra li bng nc ri thm kh b mt, em cn ghi li gi tr m.

- Mc vt m thnh catot.

- Kim tra cc in cc Ni, mc cc in cc ny thnh anot.

- Bt cng tc ngun, iu chnh gi tr dng in nc th nht. Quan st gi tr dngin hin th trn ampe k.

- Quan st hin tng, lu vt m ti b m trong 10 pht, sau tt ngun in ly vtm ra thm kh b mt em cn xc nh lng kim loi m bm trn b mt catot(ms).

Tin hnh th nghim tng t cc gi tr dng in khc nhau tng ng vi 4 nc tiptheo ca b iu chnh ngun in.

V. Kt Qu:

1. Kt qu th:

Ghi nhn cc gi tr khi lng kim loi m, gi tr dng in catot mi ln thnghim

2. Kt qu tnh:

- Tnh mt dng catot, khi lng kim loi m l thuyt theo nh lut Faraday,chiu dy lp m thu c, hiu sut qu trnh m.

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- V th hiu sut mt dng catot Ic

VI. Cu hi:

1. Nu tc dng ca cc thnh phn c trong b m Ni?

2. Trnh by cc phn ng xy ra trn cc in cc trong qu trnh m?

3. Nhn xt s nh hng ca mt dng catot ti hiu sut thu hi lp m t cckt qu th nghim?

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PH LCMu bo co th nghim

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