[tài liệu hóa học chuyên ngành online] hoá học phân tích định lượng lê thị...

WWW.DAYKEMQUYNHON.COM

WWW.DAYKEMQUYNHON.UCOZ.COMWWW.FACEBOOK.COM/DAYKEM.QUYNHON

Xs



--

-

-

-

-



--

-



-

-

-

-

-



-

-

-



-

-

-

-

-

-



---



--



Cng thc ca ET-



Bng 2 ang so phan li cua mot so axit, baz thng gap



Bng 3. ch so tan va o tan cua mot so chat ien li kho tan 18 250c

Loai chat Cong thc Tch so tan o tan (Mol/l) o tan (g/100ml) Asenat Ag3AsO4 4,5.10

-19 1,84.10-5 8.5,10-4

Bromua PbBr2

CuBr AgBr Hg2Br2

7,4.10-5 5,3.10-9 7,7.10-13 5,2.10-23

2,6.10-2 7,3.10-5 8,8.10-7 2,8.10-8

9,54.10-1

1,05.10-3 1,65.10-5 1,57.10-6

Hyroxit Ca(OH)2 Mg(OH)2

Cd(OH)2 Mn(OH)2

Ni(OH)2 Fe(OH)2 Co(OH)2 Zn(OH)2 Cu(OH)2 Sn(OH)2 Cr(OH)3 Al(OH)3 Fe(OH)3 Sb(OH)3

3,1.10-5 5.10-12

1,2.10-14 4.10-14 4,8.10-16 6,3.10-16 2.10-16 1.10-17 5,6.10-20 5.10-26 5,4.10-31 1,9.10-33 3,8.10-18 4.10-12

2.10-2 1,1.10-4 1,4.10-5 2,1.10-5 5,4.10-5 4,9.10-6 3,7.10-6 1,4.10-6 2,4.10-7 2,3.10-9 1,2.10-8 2,9.10-9 1,9.10-9 1,9.10-11

1,48.10-3 6,42.10-4 2,04.10-4 1,87.10-4 5,01.10-5 4,50.10-5 3,44.10-5 1,40.10-5 2,34.10-6 3,51.10-8 1,24.10-7 2,26.10-8

2,03.10-8 3,28.10-10

Ioua PbI2 CuI AgI Hg2I2

8,7.10-9

5,06.10-12

1,5.10-16 1,2.10-23

1,3.10-3

2,35.10-6

1,2.10-8

5,2.10-8

5,99.10-2

4,38.10-5 2,82.10-7 3,41.10-6

Cacbonat MgCO3 ZnCO3 BaCO3 CaCO3 SrCO3 MnCO3 FeCO3 Ag2CO3 PbCO3 CdCO3 HgCO3

1,0.10-5

2,7.10-8

8,1.10-9 4,8.10-9

1,6.10-9

8,8.10-11

2,5.10-11

6,15.10-12

1,5.10-13

2,5.10-14

9.10-17

3,2.10-8 1,6.10-5 9,0.10-5 6,93.10-5 4,0.10-5

9,4.10-6 5.10-4

1,15.10-7

3,9.10-7 1,6.10-6

2,8.10-3

2,70.10- 2,01.10- 1,78.10-

6,94.10-1 5,91.10-4

1,08.10-4

5,79.10-5 3,17.10-3 1,04.10-5 2,76.10-6

1,29.10-4

Oxalat MgC2O4 BaC2O4.2H2O SrC2O4.H2O CdC2O4.2H2O CaC2O4. H2O ZnC2O4.2H2O

8,57.10-5

1,2.10-7 5,61.10-8 1,53.10-8

2,57.10-9

1,35.10-9

9,2.10-3 3,5.10-4

2,4.10-4 1,2.10-4

5,1.10-5 3,7.10-5

1,03.10-4

8,55.10-3 4,26.10-3 3,05.10-3

7,45.10-4 7,01.10-4



PbC2O4 Ag2C2O4

3,2.10-11 1,1.10-11

5,7.10-6 1,4.10-4

1,68.10-4 4,25.10-8

Sunphat Ag2SO4 CaSO4.2H2O Hg2SO4 SrSO4 PbSO4 BaSO4

7,7.10-5 6,1.10-5 6,3.10-7

2,8.10-7 2,2.10-9

1,08.10-10

2,7.10-3 7,8.10-3 7,9.10-4 5,3.10-4

1,5.10-4 1,0.10-5

8,12.10-1 1,34.10-1 3,93.10-2 9,47.10-3 4,55.10-5 2,33.10-4

Sunfua MnS FeS NiS NiS CoS CoS ZnS SnS CdS PbS CuS Cu2S Ag2S HgS Bi2S3

1,4.10-15 3,8.10-19

3.10-21

2.10-28

7.10-23

2.10-27

1,2.10-23

1.10-28

3,6.10-29

1,1.10-29

8,5.10-45

2.10-47 1,6.10-19

4.10-53

1,6.10-72

3,7.10-8

6,1.10-19

5,5.10-11 1,4.10-14

8,4.10-12

4,5.10-14 3,5.10-12 1.10-14

6,0.10-15 3,3.10-15

9,2.10-23

1,7.10-16 3,4.10-17 6,3.10-17 2,7.10-15

3,22.10-7

5,36.10-9 4,99.10-10 1,27.10-13 7,64.10-11

1,27.10-13 3,41.10-11

1,51.10-13

8,67.10-14 7,9.10-14 8,8.10-22

2,71.10-15 8,43.10-16 1,47.10-25

1,39.10-13

Phot phat MgNH4PO4 Ag3PO4 Pb2(PO4)3

2,5.10-13 1,8.10-18 4,5.10-32

6,3.10-5

1,6.10-5 1,7.10-7

8,65.10-4

4,19.10-4

1,38.10-5

Clorua PbCl2 AgCl Hg2Cl2

2,4.10-4 1,8.10-10

1,1.10-18

3,9.10-2 1,35.10-5 1,6.10-5

1,08 1,86.10-4 7,55.10-4

Cromat SrCrO4 BaCrO4 Ag2CrO4 PbCrO4

3,5.10-5

2,41.10-10 1,1.10-12

1,8.10-14

5,9.10-3 1,5.10-5 1,3.10-4 1,3.10-7

1,20.10-1

3,80.10-4 4,31.10-3

4,20.10-6



1

BI NG PHN T NH L NG

ng vin: Nguy n Thi H ng



2

1.1.

1.1.1. V

1.1.2.

-Ch n nh n b

c y c

-Chuy a tan hon ton m

mi thch h ch g

m c th a tan m

ha h

-Tch ho

ha l, v 2+ c m 2+ b c

chuy 2+ thnh Fe3+ 3+b - 63-.

-Ti ch

-Tnh k

1.1.3. Phn lo

1.1.3.1.

- h kh o vi nh sau

qu trnh th

tch.

- o vi

d

1.1.3.2.

- n vi

th ng, c m

tnh ch g c



3

tch. V d 3+ c th 3

sng 450nm v c u c y t

- ha l: trong nhi g h ng

vai tr r nh d

th +: dng thu

33-

3+.

Hai y

m

-M -0,1g; m -0,01g; m

4

q% = 610Q

a

Trong nhi

m ph

nhn thm th

kh

1.2.2. Bi

1.2.2.1. N

1.2.2.2. N

1.2.2.3. N

Quan h M v CN : CN = n.CM ; D

CdCN

%..10

l s

Cng th)(mlV

aT (a: s

1.3. Sai s

1.3.1.

ph h

th .

Tham s sai s sai s

d = Xi %100d

%

Sai s gi tr .

Sai s

ph h k

l ng m



5

1.3.2. Sai s

Sai s cc sai s n nhn c

gy ra, n l

tr nh v n sai s nh phn tch.

Nguyn nhn sai s v n t

M i sai s m cho k

th -.

Sai s

M s

-Sai s phn tch

-Sai s t hay nhi

th hi

chu

-Sai s

V v m phn tch lun ph th

nh l r

th c th l

nguyn nhn chnh gy ra sai s

-Sai s m cng tc phn tch i h kinh

nghi

m

d

nhi phn tch cng th trn m

1.3.3. Sai s n

Sai s n do nh n nhn ng bi

thin theo cc chi



6

Sai s n lun xu

c u ki m ng

Sai s n khng b u m ch

nhi m ng

x .

1.3.4. tr

n. Khi ti nh phn

nh m ng m

ti nh x

quan tr gi tr nh c

1.3.4.1. Gi tr nh c X )

L gi tr h

trong s

Gi

X2,....Xn:

n

Xi

X

n

i 1

1.3.4.2. 2)

cc gi tr gi tr nh

c nh ph ng l gi tr nh,

bi

k

i

n

i XXs

1

2

2 )(_

k: s k = n 1.

chu : 2ss



7

nh c n

s

n

ssx

2

Trong thx

ssX ,, 2

trong dy gi tr gi tr X . Sau

X v s2 theo cc cng th

n

y

CX

n

i

i

1 v

11

2

2

n

x

s

n

i

i

n

y

yxi

n

i

in

i

i

n

i

i1

22

1

2

1

2

)(

v CXy ii

V d bnh c

ng theo cc s

16,2;15,4;17,5;15,9;16,3.

Ch

stt Xi% yi .10 yi2.100

1 16,2 -1 1

2 15,4 -9 81

3 17,5 12 144

4 15,9 -4 16

5 16,3 0 0

------------------------------------

2,05

1iiy 42,2

5

1

2

i

iy

Ta c: 26,165

2,03,16X

412,25

)2,0(42,2

25

1

2

i

iX



8

603,04

412,22s

7765,02ss 347,05

7765,0X

s

1.3.4.3. H

Gi nh n th nghi

ton h X , s. H

:

%100.

X

sv

T

Bin gi :L gi tr nh c

X v gi tr c X

Trong th nh ng

chu

n

tsXn

s

X

s

X

t

X

V cho. V d

0,99,.

kX

ts ,

v : h

cho trong b

Kho kho

c cho: XX

Cc gi tr



9

k

0,95 0,99

k

0,95 0,99

1 12,706 63,657 14 2,145 2,977

2 4,303 9,925 15 2,131 2,947

3 3,182 5,814 16 2,120 2,921

4 2,776 4,604 17 2,110 2,898

5 2,571 4,032 18 2,103 2,878

6 2,447 3,707 19 2,093 2,861

7 2,365 3,499 20 2,086 2,845

8 2,306 3,355 25 2,060 2,707

9 2,262 3,250 30 2,042 2,750

10 2,228 3,169 40 2,021 2,704

11 2,201 3,106 60 2,000 2,600

12 2,179 3,055 120 1,980 2,671

13 2,160 3,012

V d

ch ng trong v d n v

26,12X 347,0X

s

Tra b ( = 0,95; k = 4)

V kX

ts , =0,347.2,776= 0,96

96,026,1695,0X hay 22,1730,15

Sai s

%100%X

v v d y %059,0%10026,16

96,0%



10

1.3.5. Ch cch ghi k

1.3.5.1. Ch

K m

V v

v

Ch ng v

tin. V n t ng l b

VD: 1, 2 3 4 5 : 5 ch

(5)

o thng s u

ghi ch ch

N n cn phn tch v 0,1mg th k

ch .

V d

ch cc ch n ton tin c ta n ch

s b n thang chia. Trong k y, ta c 5

ch 1 ch

(ch

k

ph s n ph

V d khng ghi 12,8ml hay 12,854ml

qu o gi tr

c ch

V d X =3,86712 v

ph b ghi k m trn h

ph X =3,867 ( = 3,8670,005). bao g



11

ch ng v n) (cc ch tin c

ch b

1 ch

= 3,8670,005 4 ch

3 ch

ng

cng V d gi tr

-

pH.

s

l cn ch

tnh vo s V d hai ch

tnh l s n l s y c 4 ch

0, 3 l s 0 (ch ng) l s

S

0,02030

3 ch h (0)

phn th cc s o ch n b

ch

V d 3 c 4 ch .10-4 c 3 ch

s n ph 3mg

( c 2 ch 2400mg (c 4 ch



12

th cc ch n)

khng s V d

5) cn ch b

1.3.5.2. Quy t m trn s

m gi m trn s

m trn

cng.

-Php c php tr ng m

b

Y = 1,526 + 10,45 + 58,1 = 70,076 K m trn Y = 70,1

Y = 1158,451 415,28 = 743,171 K m trn Y = 734,17

-Php nhn v chia: c ng m

b

310.3589,11497,35

0279,0.7120,1Y k m trn Y = 1,36.10-3

-Php tnh logarit

VD: tnh logarit c -8

Log Y = -8+0,7917 = -7,208 (c 3 ch

trong Y c 3 ch

VD: cho pH = -lg H = 11,15. Tnh H

H = 10-11,15 = 7,0795.10-12 lm trn H = 7,1.10-12 ( c 2 ch

ngh



13

2. KH

V

2.1. Phn tch kh

2.1.1. Nguyn t a v d

Phn tch kh o vi

kh nh sau ph

Do ch

cn nn t

t

2.1.2. Phn lo

Bao g tch, c k

2.1.2.1.

2.1.2.2.

2.1.2.3.

D l h nh khi cho thu m k

v

D l s

D

V d O4 : d

Fe(OH)3 :d 2O3 : d



14

2.1.3.

2.1.3.1. Thu

2.1.3.2.

2.1.3.3. N

2.1.4. L r

L K n, y m

nhau ph

R ng

cc lo

K

trong c ch

m n b n gi r n gi

2.1.5. Chuy nh d

2.1.6. S

2.1.7. Ph

in c chnh xc khi

trung bnh v -0,4%.

2.2.

2.2.1.

o

vi h thu bi

xc (dung d

tch (A).

nh bc h

2.2.2. M khi ni

A + B C

(ch



15

Qu trnh l qu trnh thm t bi

o dung d nh ph

ch m vo v

ch nh ph

ng ch

cho tn hi u, k ..) t nh

ch r

k nh .

Trong th ng nhau v gy ra

sai s

Dung d l dung d bi

2.3. Phn lo

g php chu

-kh



16

2.4. Cc cch chu

2.4.1.1. Chu

2.4.1.2. Chu

2.4.1.3. Chu

2.4.1.4. Chu

2.4.1.5. Chu

2.5. Tnh k

2.5.1.1. tr

2.5.1.2.

2.5.1.3.



17

3. -

3.1. Nguyn t

o

ph : A1 + B2 B1 + A2

3.2. Ch

3.2.1. Khi ni

Cc yu c

3.2.1.1. L thuy v

1)Thuy

2)Thuy u:

3) Thuy -nhm mang mu:

3.2.1.2. Kho u c

Kho u c

pH c mu c th m

nh

Ind

HIndpKpH ct

0

lg (2)

pKct = - lgKct : g ch

nh c u c

pH c

T HInd0 / Ind- c

Trong th a tr

dung d u c m n th

M h u c

d y l

ch



18

V d

HInd0 / Ind- 4,5; pH 3,1

Mu vng khi HInd0 / Ind- 4,5; pH 4,4

Khi pH 3,1 m

Khi pH 4,4 m u vng

u c

d Kho

kho u c

V d HInd0 / Ind- =10, Kct = 10-9 ;

pH = pKct 1 nn kho u t -10.

V u c

khi pH c mu c m

nh

3.2.1.3. Ch

i ta nh u c

m t u c nh Gi tr

ch V

pH n u m t y mu c

ch nh

3.2.1.4. Cc y u c

1)Hi

2)

3) h c dung mi:.

4)Th n

3.2.2. Sai s

Trong phn tch th i sai s s

(pipet, buret, bnh n cn sai s



19

trng v sai s

b ng v

3.3. a v

3.3.1. Khi ni

Qu trnh chu ng bn ngoi m m

u s

ng ch n m

nh bi

th m vo (% hay Vml) ta s n t

V

dung d n c m vo trong qu trnh

C

n c

thu nh

B h ton v th

trnh chu m m

chu y g nh chu d

ch

3.3.2. Nguyn t

N

p

F



20

3.4. Chu

3.4.1. Chu

chu dung d N b dung d NaOH 0,1M

pH

100

4,3

9,7

7

VNaOH



21

3.4.2. Chu

3.5. Chu

3.5.1. Chu

3.5.2. Chu

g chu n dung d NH4OH 0,1 N b dung d HCl 0,1 N

5,28

pH

100

4,3

6,26

VHCl (ml)

2

1

8,8

6,8

10,6

pH

100 VNaOH



22

3.6. Chu

3.6.1. Chu

Kh nh chu dung d H3PO4 0,1M b

NaOH 0,1M.

H3PO4 H+ + H2PO4

- K1=7,51.10-3 ; pK1=2,15

H2PO4- H+ + HPO4

2- K1=6,23.10-8 ; pK2=7,20

HPO42- H+ + PO4

3- K1=2,2.10-13 ; pK3=12,38

Theo cc n n, dung d 3PO4

H3PO4, H2PO4-, HPO4

2- v K1 >> K2 >> K3 v v y khi

dng NaOH chu H3PO4 s a l

H3PO4 + NaOH NaH2PO4 + H2O

H2PO4- + NaOH Na2HPO4 + H2O

HPO42-+ NaOH Na3PO4 + H2O

*Tnh pH c

*Nh

-

3 2 1

13

S

pH

4

5

9

H3PO4

NaH2PO4

Na2HPO4



23

c th

v h i c au t nh4 l

Trong th

Cho tc d 2

2H3PO4 + 3Ca2+ = Ca3(PO4)2 + 6H

+

6H+ + 6OH- = 6H2O

-Ch ng metyl da cam,

ng phenolphtalein.

3.6.2. Chu

Xt c nh 2CO3

0,1M b K1 = 4,3.10-7, K2 = 4,8.10

-11

(pK1=6,36, pK2=10,3)

CO32- + H+ HCO3

- (1)

HCO3-+ H+ H2CO3 (2)



24

4.

4.1. Gi

1)Complexon I l axit nitriltriaxetic (NTA), k hi 3Y, cn g trilon A.

CH2COOH

N CH2COOH

CH2COOH

Complexon I t n t dng.

2)Complexon II l axit etylen diamin tetraaxetic (EDTA), k hi 4Y, t

tan tr

HOOC-CH2 CH2-COOH

N-CH2-CH2-N

HOOC-CH2 CH2-COOH

3) Complexon III (trilon B) : mu

(mu 2Y2-, trong phng th nghi

g EDTA.

NaOOC-CH2 CH2-COOH

N-CH2-CH2-N

HOOC-CH2 CH2-COONa

4.2. S

4.2.1. Ph

M i v s

trong phn tch th axit etylen diamin tetra axetic (EDTA):

HOOC-CH2 CH2-COOH

N-CH2-CH2-N

HOOC-CH2 CH2-COOH

EDTA l axit 4 n 4Y: K1 = 10-2, K2 = 10

-2,76, K3 = 10-6,16, K4 = 10

-10,26.

v ng mu 2H2Y2,

complexon III (thi quen v EDTA)



25

EDTA t trong h

Mn+ + Y4- MY(n-4)+

V cao.

cc php chu nh khi c m

t pH xc

kim lo

S

H4Y H+ + H3Y

- K1

(1)

H3Y- H+ + H2Y

2- K2

(2)

H2Y2- H+ + HY3- K3

(3)

HY3- H+ + HY4- K4

(4)

S h

Mn+ + H2O MOH(n-1)+ + H+ 1

(5)

Mn+ + 2H2O MOH(n-2)+ + 2H+ 2

(6)

...

Mn+ + jH2O MOH(n-j)+ + jH+ j

(7)

(j = 1 N v ion kim lo

S

Mn+ + X MX 1

(8)



26

Mn+ + 2X MX2 2

(9)

Mn+ + nX MXn n

(10)

(n = 1 N v ion kim lo

Ph

Mn+ + Y4- MY(n-4)+ MY

(11)

S nh:

MY + H+ MHY KMHY

(12)

MY + OH- MOHY KMOHY

(13)

4.2.1.1. *S nh cc complexonat

N

OOCCH2

CH2 CH2 N

CH-CHOO

CH2-COONaCa

NaOOC-CH2

Ph ion kim lo n+

Me2+ + H2Y2- MeY2- + 2H+

Me3+ + H2Y2- MeY- + 2H+

Me4+ + H2Y2- MeY + 2H+

4.2.2.

d hu

g n vi



27

,,

,

.'

YM

MY (14)

[MY]= t EDTA

[MY]= [MY] + [MHY] + [MOHY] (15)

T (15) v (13) ta c:

[MY]= [MY](1 + KMHY[H+] + KMOHY[OH

-] (16)

[M]= t

v n

[M]= [M] + N

n

N

j

j MXMOH1

'

1

)( (17)

T -10) ta c:

[M]= [M] (1 + N

n

n

n

N

j

j

j XH1

'

1

(18)

[Y] = t

kim lo

[Y] = [Y] + [HY] + [H2Y] + [H3Y] + [H4Y] (19)

T -4) ta c:

[Y] = [Y](4321

43213212

213

14

KKKK

KKKKhKKKhKKhKh) (20)

(h = [H+])

T

MY

YM' (21)

MY = (1 + KMHYh + KMOHY[OH-])-1 (22)

M = (1 + '

1

*N

j

jjh +

N

n

n

n X1

)-1 (23)



28

Y = 4321321

221

31

44321

KKKKhKKKhKKhKh

KKKK (24)

n)

vo pH c n

ch

cho c m

4.3. Tnh n nh chu Sai s

4.3.1. Tnh n nh chu

Ta hy thi nh t nh chu

mu o, Vo) b

p d n n

'' MYMVV

VCC

O

OOM

(25)

'' MYYVV

CVC

O

Y (26)

(25) tr VV

CVVCYM

O

OO'' (27)

Chia c oVo, bi

01)''( FVC

VVYM

OO

O (28)

T ,

,,

'

1

M

MYY (29)

,'( MVV

VCMY

O

OO (30)

nh t (29), (30):

(,

1

'

1

M VV

VC

O

OO -'

1- [M])

VV

VC

O

OO + 1 F = 0 (31)

Khi > 108 ta c th

VV

VCMY

O

OO'( (32)



29

Tnh ton m nh chu

-

VV

CVVCM

O

OO' (33)

-T

0)''(OO

O

VC

VVYM

(34)

T VV

VCM

O

OO.1

' ,2 (35)

T CV = CoVo ta c:CC

CC

VV

VC

O

O

O

OO (36) thay vo (35):

CC

CCM

O

OT ,

, 1 (37)

- [M]

30

544

343

332

3231

2 10.4775,110.7681,6

1

1

1

NHNHNHNHZn

Y = 4321321

221

31

44321

KKKKhKKKhKKhKh

KKKK

V h = 10-9

31

dung d 2+ b -10

NH3+NH4 3] = 0,100M

Nh

+ chu

nh 11,10

pZn l 10,13 1%.

4.3.2. Sai s

G sai s S = F-1, t

S = OO

O

VC

VVMY )''( (42)

OVO nn

CC

CC

VV

VC

O

O

O

OO (43)

T nh t :

S = O

O

O

O

CC

CCM

CC

CC

M)

11.

1( ,

,,,

Hay S = O

O

CC

CCM

M)

1(

1.

1 ,,,,

(44)

8 (ph th,

1 lc ny pt sai s

S = O

O

CC

CCM

M

,

,,

1.

1 (45)

V d : Tnh sai s 2+ 0,001M b

3 + NH4 3] = 0,100 M, n

php chu

n ta c:

52 10.4775,1Zn Y 0521,0 ZnY =10

10,39 > 108

Nn [Zn2+] = 17,65

11

1010.4775,1

10



32

Thay cc gi tr o (4

S= %13,0001,0.001,0

001,0001,0.10

10

1

10

1 17,617,639,10

V d : Chu ng n

thm 24,5 ml EDTA. a)

V d : Xy d ng

n dung d

4.4. Cc ch

4.4.1. Yu c

4.4.2. M

4.4.2.1.

L ch

N

OH

HO3S

O2N

N

OH

K hi 2In- (pK2 = 6,3; pK1 trong phn t

c nhm sunfo ha nh n t

hydro trong k hi proton c

trong dung d

H2In-

pK1 = 6,3 HIn

2- pK2 = 11,5

In3-

da cam

N 2+ -11 b ng ch

ETOO t MIn- + HY3- HIn2- + MY2-



33

Mu chuy MIn- sang xanh c 2-.

N 2+ t

HIn- + M2- MIn- + H+

Mu chuy HIn2- -.

4.4.2.2. Murexit

Thu u azo v c

Anion murexit c m

K hi 4In-. B n t proton c

amino.

H4In- H3In

2- + H+ K2 = 10-9,2

tm

H3In2- H2In

3- + H+ K3 = 10-10,9

Tm xanh tm

Mu Ca H2 2In, NiH2In, CoH2In : vng.

Khi chu - ch

th u tm H3In2- l s u r nh

4.4.3. S

H nh

c m s u c hi chu

mu t u c ch u c

t o pH.

dng h

M + In MIn MIn = ,,,

. InM

MIn (46)

[MIn]: t kim lo

[MIn]= [MIn] + [MIn2] +...



34

[M]: t

th v

[M] = [M] + N

n

N

j

j MXMOH1

'

1

)( X: ch

[In]: t

lo

[In] = [In] + [HIn] + [H2In] + ...

T MIn = MIn.MIn

InM (47)

M = (1 + '

1

*N

j

jjh +

N

n

n

n X1

)-1 (48)

In = 32121

21

3321

KKKhKKhKh

KKK (49)

n)

T,

,

In

MInl t

v y quy

mu c

u:

[M]= .1

, ,

,

In

MIn (50)

Gi,

,

In

MIn= p c s u r th

[M]= MIn

p,

(51)

Hay MIn - lgp (52)

N khi p 10 (mu c

MIn chi 10-1 (mu c kho

mu c : MIn 1



35

V d s u x

t 50% : p[M] = lg MIn

h MIn ta c th u v

V d Chu 2+ 1,00.10-3M b -3 M

thi 3+NH4 3] = 0,1M, dng ETOO lm ch

Hy

Ph ch

Ca2+ + In3- CaIn- CaIn = 105,4

Ph

Ca2+ + Y4- CaY2- CaY = 1010,7

CaIn- + Y4- CaY2- + In3-

Cc ph

Ca2+ + H2O CaOH+ + H+ *CaOH+ = 10-12,6

H2In- H+ + HIn2- K2 = 10

-6,3

HIn2- H+ + In3- K3 = 10-11,6

Do *CaOH+ = 10-12,6

36

CaY = CaY .35,10

CaIY

10. YCaYYCa

a)Khi d r

do:

T CaIn = 3,79

V CaY = 1010,35 > 108, nn p d

S = %4,3210.10

1010.10

10

1.

10

133

3379,3

79,335,10

b)Khi d

do:

T [Ca] = 9

1.

1.

1,,

,

,CaInCaIn In

CaIn nn [Ca]= 1,8.10-5

S = %6,310.10

1010.10.8,1

10.8,1

1.

10

133

335

535,10

4.5.

4.5.1. Chu

4.5.2. Chu

4.5.3. Chu

4.5.4. Chu

4.6.

4.6.1. Chu

o ph g t 2+ v

haloganua, CN-, SCN-,... v diphenylcacbazit, diphenylcacbazon trong

V d + + Cl- HgCl- K1 = 5,5.106

HgCl+ + Cl- HgCl2 K2 = 3,0.106

HgCl2 + Cl- HgCl3

- K3 = 7

HgCl3-+ Cl- HgCl4 K4 = 10



37

Hai ph v

vo 2 ph

4.6.2.

o ph +(dung d 3) v

ion xyanua CN- t 2]-:

Ag+ + 2CN- Ag(CN)2-

N + th l

Ag(CN)2- + Ag+ Ag[Ag(CN)2] (TAg[Ag(CN)2] = 10

-

12)

k

Ag[Ag(CN)2] .

ion kim lo 2+,

Co2+, Cu2+, Zn2+ v chng t - nh Ag(CN)2-

v ph

V d - vo dung d 2+ trong amoniac

th ton b 2+ s ng ph Ni(CN)42- b Ag(CN)2

-

- b

4.7. Cc ch

4.7.1. Ch

4.7.2. Ch

4.7.3. Ch



38

5.

5.1. Ch a kh

5.1.1. Tr h khng dng ch i vo

5.1.2. Dng ch i vo

5.1.2.1. Ch

5.1.2.2. Ch

Lo mu c d

nhau v khng bi

V d 3+ b 3

axit v

3Sb2+ + BrO3- + 6H+ 3Sb3+ + Br- + 3H2O

dung d N 3 th s

ph BrO3- + 5Br- + 6H+ 3Br2 + 3H2O

Br2 sinh ra s nh 1 h

mu, ta k

5.1.2.3. Ch

Ch nh mu c

(IndOX) v d Kh

t

IndOX + ne IndKh

Th n h y tnh b nh Nerst:

Kh

OX0

Ind

Indlg

n

059,0EE

bKh

OX

Ind

Ind.



39

M u c o l tu o t

n d m c th

nh u c

ngh l:

Khi Kh

OX

Ind

Ind 10 : dung d u d OX,

1 n

059,0E 0

Khi Kh

OX

Ind

Ind

10

1: dung d u d Kh,

2 n

059,0E 0

u c u c

IndOX sang d Kh ( m

n

059,0E 0 Ed.d

n

059,0E 0

v kho y g kho u c

V u c th kho

E m trong kho mu c

kh

: do 0,059/n l qu nh u g ng v

tr 0 c 0

c dng th u.

M ng:

Ch Mu d

oxy ho

Mu

d

E0

khi[H+]=1

Diphenylamin Xanh tm khng mu +0,76V

Axit diphenylazosulphonic khng mu +0,84V

Axit phenylantranilic khng mu +1,08V



40

Pheroin Xanh nh +1,06V

Axio,o-

diphenylamindicacbonic Xanh tm khng mu +1,26V

5.2. oxy ha kh

5.2.1. n oxy ha kh

b nhau

5.2.2.

khc nhau

*C Fe2+ 0,1M b 4- 0,1M (pH = 0) :

Fe2+ Fe3+ + e E2 = 0,68V

MnO4- + 8H+ + 5e Mn2+ + 4H2O E1 = 1,51V

T : )(371,151

51,1.568,0.1VEt

:

857,0001,0

001,01lg

1

059,068,0E

474,1001,0lg5

059,051,1cE

E(V) 0,620 0,680 0,736 0,797 0,857 1,371 1,474 1,486 1,498 F 0,09 0,50 0,90 0,99 0,999 1,00 1,001 1,010 1,10

Nh :

F

E

1,3

0,8



41

5.2.3.

ha kh khc nhau

Cr2O72-+ 6Fe2+ + 14H+ = 2Cr3+ + 6Fe3+ + 7H2O

Hay tdtd

tdFe

EE

Cr

EEE

312

312

2

3lg

7

059,0

7

6

2

1lg

7

059,0

7

6

thu

5.3. M oxy ha kh hay dng

5.3.1.

5.3.1.1. Nguyn t

n ph c

ion MnO4-

MnO4- + 5e- + 8H+ Mn2+ + 4H2O v

0MnO4-/Mn2+ =

1,51V

5.3.1.2. M y l:

a)Ch :

b)KMnO4 khng ph ch

c)Ch n chu H2SO4

Tuy nhin, qu trnh chu :

+Khng ti 3 v HNO3 s m

sai k

+Khng ti :

10Cl- + 2MnO4- + 16H+ 2Mn2+ + 5Cl2 + 8H2O (**)

ph y bnh th x h 2+ v MnO4-

gy c lm cho ph

Ph ph

d 2SO4, H3PO4, MnSO4



42

H2SO4

Fe2+ b 2 trong khng kh, t

H3PO4 : Fe3+ nh thnh c mu vng gy c

u ph 4), H3PO4 t

Fe3+ ph u FeHPO4+.

Mn2+ ( MnSO4): h

5.3.1.3.

5.3.1.4.

5.3.2.

5.3.2.1. Nguyn t

y l ph ng php chu oxi ho kh d n ph ho c

ion cromat Cr2O72-

Cr2O72- + 14H+ + 6e 2Cr3+ + 7H2O E

0Cr2O72-/2Cr3+=1,33V

5.3.2.2. M y l:

a)Ch

b)K2Cr2O7 l ch r

c) 2SO4, H3PO4 v

HCl (v E0Cr2O72-/2Cr3+=1,33V; E0

Cl2/2Cl-=1,33V). Tuy nhin, khng ti nh trong

lc ny n - r

th 2/2Cl- v Cr2O7

2- s - thnh Cl2.

5.3.2.3.

5.3.3.

5.3.3.1. Nguyn t

n ph 2 v ph-:

I2 (r 2I- E0I2/2I-=0,54V

T tr 0I2/2I- ta th 2 l ch 4, K2Cr2O7 nh-

l ch nhi

kh ng c 2) v

kh - ch ch



43

ng ph 2O32-) v

-thiosunfat, ph

I2 + 2e 2I-

2S2O32- - 2e S4O6

2-

2S2O32- + I2 S4O6

2- + 2I- E0S2O32-/S4O62-=0,1V

5.3.3.2. M

a)Ch :

b)Natrithiosunfat Na2S2O3 c th

Na2S2O3.5H2 ch dung d 2S2O3 khng b

d 2, O2 v vi sinh v

m vo 10mgHgI2 /1 lt dung d 2S2O3):

Na2S2O3 + CO2 + H2O NaHCO3 + NaHSO3 + S

Na2S2O3 + O2 Na2SO4 + S

c)Qa trnh chu -thiosunfat c nh

n h th ph

s I2 + 2OH- IO- + I- + H2O

IO- t nh c tnh oxy ho m 2O32- thnh

SO42-:

S2O32- + 4IO- + 2OH- 2SO4

2- + 4I- + H2O

+ lm pH c

ph ng NaHCO3+ trong dung d

HCO3- + H+ = CO2 + H2O

I2 l ch kh 2 c

nhi nh php chu y.

I2- + I2 I3

- (*)



44

khi s y ph Ph 3- l ph

thu ion I3- r n khi dng Na2S2O3 2, cn b

(*) b chuy 2

b 2S2O3.

Ph gi 2 v I- v

ch m I2 hay I- vo dung d

dung d o ch nh sng lm t - thnh I2 b

O2 trong khng kh) r nh chu

4I- + 4H+ + O2 2I2 + 2H2O

5.3.3.3. -thiosunfat

V d SO32- + I2 +H2O SO4

2- + 2I- + 2H+

Sn2+ + I2 Sn2+ + 2I-

oxy ho :b

ny ti nh theo nguyn t m vo dung d

t - v ch n ton. I- b

oxy ho thnh I2 (tan nhi g KI nn ph 2 thot ra

( 3-) b 2S2O3.

V d 2, MnO4-, Cr2O7

2-, Fe3+,...

Br2 + 4I- 2Br- + I2

2MnO4- + 10I- +16H+ 2Mn2+ + 5I2 + 8H2O

Cr2O72- + 10I- +16H+ 2Cr3+ + 3I2 + 7H2O

2Fe3+ + 4I- 2Fe2+ + I2

+c

v o ph 5I- + IO3- + 6H+ 3I2 + 3H2O



45

T nh ta th + tham gia ph

I2 gi hon ton, ta chu 2 thot ra

b dung d 2S2O3. T+ trong dung d



46

6. HP CHU

6.1.

Trong th ng l:

o ph + (AgNO3) v

halogenua (Cl-, Br-, I-) v SCN-.

Ag+ + X- AgX

- b

Hg2X2 . Hg22+ + 2X- Hg2X2

Zn2+ b

ch

2K4 Fe(CN)6 + 3Zn2+ K2Zn3 Fe(CN)6 2 + 6K

+

4)Chu 2+ b Ba2+ + SO42- BaSO4

v rodizoonat natri lm ch 2+ th dung d

nhu

5)Chu 2+ b +,

hi CrO42- + Ag+ Ag2CrO4

6.2.

6.2.1.

Kh nh 0,V0)

b 3(C,V) bi AgCl = 10-10, pAg + pCl = 10

Ph Ag+ + X- AgX

Khi thm Vml dung d : [Ag+].[X-] = TAgX (1)

n n

[X-] + mAgX = VV

VC

o

oo (2)

v [Ag+] + mAgX = VV

CV (3)



47

(mAgX: s

(3) tr +] - [X-]= VV

VCCV

o

oo v chia 2 v y cho

VV

VC

o

oo oo

oAgX

oo

oo

VC

VV

Ag

TAg

VC

VCCV)(

oo

oAgX

VC

VV

Ag

TAgF )(1 (4)

[Ag+] v [X-] nn ph

V d Kh

dung d 3 0,1M, cho TAgCl = 10-10, TAgI = 10

-16

Ta tnh pAg ho

Khi F = 0,999 p d ta tnh pAg, pCl, pI

Khi F = 1,001 p d

Tnh ton v

li

6.2.2. Sai s

Tnh sai s o (4).

pAg

V AgNO3

6,7

4,3

BN



48

N (4) s :

oo

o

c

AgX

cVC

VV

Ag

TFS 1 (8)

N d (4) s :

oo

oc

VC

VVAgFS 1 (9)

N d gi ).

6.3.

6.3.1.

Ag+ + Cl- AgCl K2CrO4

T 3,

xu 2CrO4 ta s

Ag+ + CrO42- Ag2CrO4 TAg2CrO4 = 1,1.10

-12

V : ph 2CrO4

hi khi: pAg = pCl = 5 (TAgCl = 10-10)

2CrO4 th Ag+ 2 . CrO4

2- 2.10-12

CrO42- 2

25

12

2

12

10.2)10(

10.210.2

AgM

V mu 2CrO4 th

mn: 2.10-4M C K2CrO4 2M.

Tuy nhin, v

nh 2CrO4 nn th ng dung d

K2CrO45.10-3

- + v OH- t 2O:

-C 2+, Pb2+, Bi3+ (v chng t

CrO42-); S2-, SO4

2-, PO43-, C2O4

2- (v chng t +).

-Dung d 3 bao gi



49

- 2CrO4

nn ph

6.3.2.

3 b

NH4SCN chu Fe3+ n FeNH4(SO4)2.12H2O 1M (dng 1 -2

ml dung d n s n 100 ml h

Cl-) theo nguyn t

3 :X- + Ag+ AgX + Ag+(cn

l +cn l 4SCN theo

php Volhard tr T + ph - v -.

: trong s -, I- thu chnh - v k AgCl = 10

-10 , k SCN

c TAgSCN = 10-12 + cn l

ng NH4SCN lm dung d

nhu - k +

c gCl tan phn li ra.

AgCl Ag+ + Cl-

Ag+ + SCN- Ag SCN

Mu - ng

2 bi ng

NH4+cn l m m

6H5NO2 m ch nh phn li c

AgCl ti -.

xit do

AgSCN khng tan trong axit nn ta c th2+, Pb2+ khng gy c



50

php ny. Cc ion c -, cc ch

ho s ho SCN-, ch 3+ 43-, F-.

6.3.3.

6.3.3.1. Hi nh

Trong qu trnh cc

halogenua b

t n s ng d

V d 3 ta th -, k -

t nh h AgI + mI- nAgI.mI- +, ta l

pAgI + qAg+ pAgI.qAg+

Tr

c th ng ho o b

6.3.3.2. Ch

Ch nh u h y

anion c n b

bi u. L

Cc ch ng l fluoretxein v cc d eozin.

V d m HE. Trong

dung d H+ + E-

E- u h u tm hoa c.

N

dung d 3 th : - khng h - v cng d -), E- v

u h + s -, k u tm

hoa c.



51

6.3.3.3. xc c ng ch o

cc y

a)Tnh h ch

ch

y cn tu c vo l

nh cn ph o tnh ch

c v u c th

V d - v chi v

AgCl, Cl- Na+ + flBr- AgCl, flBr- Na+ + Cl-

b) u b n

v pH thch h

s u r.

V d axit r A= 10-7

52



Bi Xun V ng Ha Phn Tch ng

I: GI I THI U

n vi c tch, nh n bi nh nh

i c a nh ng c u ph n c a m t m u v t ch nh tnh cho bi t s

c m t c a chng trong m u, cn phn tch ng thi t l ng t i

c a m t ho c nhi u c u ph n ny, hay cn g i l ch i d ng

s h i h c khi m c

di n ra. M ng c n thi t cho m nh tnh v

phn t ng.

1.1. Vai tr c a phn tch ha h c trong khoa h c

Ha h t vai tr c t y u trong khoa h c. T cu i th k 19,

ha h ngh thu t nh n bi t nh ng ch t khc nhau v

nh nh ng thnh ph n c a chng v gi m t v tr n i b t trong s nh ng

ng d ng c a khoa h c, b i v n gip tr l i nh ng cu h i n y sinh nh ng

qu trnh ha h c ti n hnh v i nh ng m c hay k thu t.

Ngay t th i , ha h chuy n t m t ngh thu t thnh m t

ngnh khoa h c v i nhi u ng d ng trong cng nghi c ph m, v t t c

cc ngnh khoa h c.

t vi v d minh h a:

- Hm ng c a hydrocacbon, NOx, v CO hi n di n trong kh th c

nh m c nhi ng khng kh.

-P nh b i li t c a nh ng b nh nhn.

-P nh ng c c ph m gip thi t l ng protein

v gi tr ng c a chng.

-Phn tch thp su t qu trnh s n su u ch nh nh ng n c a

nh ng nguyn t c d o, kh

ng mi mn




- Vi ng cy tr t tr ng gip nng dn thi t l p nh ng

k ho ng s ng c a cy tr ng su t

v ma.

Cc ng c t vai tr c t y u trong nhi u l c

trong ha h c, sinh ha, sinh h a ch t h c, v nh ng ngnh khoa h c khc.

V d , cc nh ha h c lm sng t c a nhi u ph n ng ha h c thng

qua nh ng nghin c u v n t c ph n ng. T tiu t n c a ch t ph n ng v

s t o thnh s n ph m trong m t ph n ng ha h c c th c tnh ton t

nh ng t i nh ng kho ng th i gian b ng nhau.

P ng c a cc ion kali, canxi, natri c d ch c ng v t

cho php cc nh sinh l h c nghin c u vai tr c a nh ng ion ny trong s

truy n d n tn hi n kinh v s co gi

Ha h c phn tch l m t cng c quan tr ng trong nh ng c g ng c a cc nh

nghin c u ny.

1.2. Phn lo

Cc nh ha h ng phn lo theo b n ch t c a

i cng tnh ton k t qu ng:

- Php cc kh ng v th tch

- P a m ng t l v ng c a ch t c n phn tch trong

m ng hon thnh lun php phn tch.

C th :

P ng: d a trn vi c nh kh ng c a ch t

c n phn tch hay cc h p ch n n.

P ch th tch: d th tch c a m t dung d ch

chu n c n tc d ng hon ton ch t c n phn tch. m

th sau:

- axit

- k t t a




- complexon

- g php chu oxi ha kh

) bo g m:

P n ha:

th , dng, n tr n h c khc.

P : d a trn nh g tc gi a b c x n t

v nh ng nguyn t ho c phn t c a ch c d a trn s t o

thnh nh ng b c x y t ch

t tch cc ch t c n phn tch hon

ton ra kh i nhau r i d tm v ng chng b ng m

php quang ph , n ha

Cu i cng, nhm nh ng tnh

ch s kh n tch (ph kh i), nhi t ph n ng, t ph n

d n nhi khc x .

1.3. c ti n hnh trong m ng

M ng tiu bi u bao g m nh c l c

minh h a trong hnh 1. Trong vi tr ng h p, c th b qua m t ho c.

Ch

Thu th p m i di n

Chu n b m u th nghi m

Ha tan m u

Lo i b nh ng s c n tr




a

Ch t c n phn tch

Tnh ton k t qu

D tin c y c a k t qu

Hnh 1.1 c trong m ng

1.3.1. Ch

c quan tr ng nh ch n l a c th i h i kinh

nghi m c c gic c i phn tch.

Xem xt quan tr ng tr c h t l m i h i. Tuy nhin tin c y

cao h i h i m t s n v th c ch n

ng l s th a hi p gi chnh xc v hi u qu kinh t .

Xem xt th n nh ng y u t kinh t l s m

N u phn tch m ng m ng xuyn, chng ta c th c g ng tiu

t n th i gian cho nh ng ho ng chu n b t l p v chu n ha

thi t b v d ng c c n b cc dung d ch chu n. N u ch c m t vi

m u c n phn tch th c n tm ph c ho c gi m thi c

nh c chu n b

Cu i cng, s ch n l chi ph i b i s ph c t p c a

m u cng s c u ph n trong m u.

1.3.2. L y m u

c nh ng thng tin c ngh t php phn tch ph c th c

hi n trn m t m u m thnh ph n c i di n trung th ng v t

ch t m c l y t .

ng nh t th c i h i m t c g ng

l l y m i di n. Vi c l y m u c a nhi ng h




ng h n hay ph c t p th m u l

ph i di n cho ton b c khi di n ra m t php phn tch.

1.3.3. Chu n b m t m u th nghi m

M u r c nghi n nh gi c h t, tr m b o s ng

nh trong nh ng kho ng th c khi qu

trnh phn tch c b u. S h p th v gi i h p c c c th x y ra

trong su t nh c ny, ph thu m c ng. B i v b t k

s m t hay nh c s i thnh ph n ha h c c a m u r n ny, vi c

lm kh m u nn ti c khi b u vi c phn tch. M t cch khc

ng m c a m u c th nh trong m t th t c ring khc. Nh ng

chu n b m u cho phn tch v lm kh m u ho nh

m c a m u c c tham kh o trong cc ti li u.

1.3.4. Chu n b dung d ch m u

Ph n l c th c hi n v i m u d ng dung d ch. Dung mi

nn ha tan ton b ng m u m t cch nhanh chng v hon ton, ch khng

ph i ch ha tan ch t c n phn tch. Nh u ki n ha tan m u nn v

cho vi c m t ch t c n phn tch khng x y ra. Tuy nhin, nhi u m u khng

th ha tan trong nh ng. V d ng khong v t

silic, nh ng polime cao phn t ho c nh ng m ng v t. S chuy n ha

nh ng ch t c n phn tch trong nh ng m u ny thnh d ng c th ha tan

ng kh v t n nhi u th i gian cho vi u v i cc axit m

m nh, nh ng ch t oxi ha, ho c ch t kh , ho c k t h p chng l i; t chy

chng trong khng kh hay oxi, ho c thiu nhi t nhi cao.

1.3.5. Lo i b nh ng y u t c n tr

C r t t nh ng tnh ch t ho c ph n t ch t c n phn

tch. Nh ng ph n c s d ng ho c nh ng tnh ch trong phn

tch a m t nhm nguyn t ho c h p ch t. Cc ch t khc

v i ch t c n k t qu cu c g i l nh ng ch t

c n tr . M t th t nh ph tch ch t c n phn tch kh i




nh ng y u t gy nhi c th c hi n. Khng c

nh ng qui lu t chung cho vi c lo i b nh ng y u t gy nhi

tch l m t trong nh lo i b chng.

1.3.6. S nh chu

Trong phn tch th tch, th tch c a dung d ch chu n tiu t ph n ng v a

v i ch t c

Trong phn tch tr ng, kh ng c a k t t a ch a c u ph n c n phn

tch trong m

T t c k t qu tch ha l ph thu c vo

i cng X c a m ng v t l c a ch t c ng

ny ph i theo cch l p l c bi t v i n CA c a ch t c n

phn tch. M t cch l t l tuy n tnh v i n ng

sau:

CA = k.X (1.1)

ng s t l .

y qu trnh xc nh k l m c quan tr ng trong h u h t cc php

c g i l s nh chu n (calibration).

1.3.7. Tnh ton k t qu

Vi c tnh ton n ch t c n phn tch t nh ng s li u th c nghi ng

l cng vi c d c bi t v i s tr gip c a my tnh hi n nay.

Nh c d a trn nh ng s li u th th c nghi u

c thu th ng h s t l c a ph n ng ha h c m php

phn tch d a vo, v nh ng h s c a thi t b .

1.3.8. t qu t vi c d t in c y

Cc k t qu n u khng c s d tin c y

c a chng. i phn tch ph i cung c p vi tiu ch c a b nh lin quan

n k t qu c tnh ton.




2: PHN TCH TR NG

2.1. M u

c d a trn vi ng g m

hai lo i chnh.

- t t a

Ch c chuy n v m t d ng k t t a kh ha tan. K t t a ny sau

c l c, r a s ch ch t nhi m b n v chuy n v d ng c thnh ph n xc

nh b i x l nhi t thch h p.

V d : M t trong nh nh canxi c t nhin l cho

alic H2C2O4 vo m t th tch chnh xc c a m c. Thm vo

NH3 t t c canxi trong m c k t t i d ng canxi oxalate:

Ca2+ + C2O42- CaC2O4 (r)

K t t c l c, r a s y ng trong c c cn chnh xc, lm

kh, v nung nhi thch h chuy ng k t t a v d ng CaO:

CaC2O4 (r) CaO (r) + CO (k) + CO2(k)

C c v s n ph c lm ngu i, cn, suy ra kh ng c a CaO v hm

ng c a canxi trong m u.

-

Ch t c n phn tch ho c s n ph m phn h y c i nhi

thch h p. S n ph c thu v cn; ho c kh ng c a s n

ph nh m t cch gin ti p t s hao h t kh ng c a m u.

V d : Natri hydrocacbonat trong vin thu c ch ng nh b ng

cch cho tc d ng v i axit sunfuric long d chuy n ton b v CO2

NaHCO3 + H2SO4 CO2 (k) + H2O (l) + NaHSO4

CO2 c d n vo m t ng ch a ch t h p thu l NaOH r n. S khc

nhau v kh ng c a c v sau khi h c s d tnh kh i

ng c a natri hydrocacbonat trong m u thu c.




2.2. Tnh ch t c a k t t a v cc thu c th t o k t t a

K t t a c c n c nh ng tnh ch t sau:

D l c v d r a s ch cc ch t nhi m b n.

ha tan th trnh m b m t trong qu trnh l c v

r a.

Khng tc d ng v i cc ch t trong khng kh.

C thnh ph c lm kh ho c nung.

phn tch m t ch t trong m u b ng c n ph i dng

thu c th t o k t t a. Thu c th thm vo t t nh t ch ph n ng m t cch ch n

l c v i ch t c n phn tch t o k t t a. ng cc thu c th c hi u r t

hi m khi tc d ng v i ch m t ch t c n phn tch m tc d ng m t s gi i h n

cc ch t.

Ch m t vi thu c th c t t c cc tnh ch t trn.

ta s c k t t a d l c, nguyn

ch t c thnh ph nh.

2.2.1. c h t v tnh d l c c a k t t a

2.2.1.1. Cc y u t c h t c a k t t a

c h t c a k t t c t o thnh r t khc nhau.

K t t a t o thnh c th l cc k t t nh hnh c kch th c h t r t

nh khng nhn th y b ng m ng (t 10-7 n 10-4 ng knh). Cc h t

ng sa l ng t dung d ch v c l c.

K t t a t o thnh c c th l cc h t v c hng ch c l n l

s phn tn c a cc h c g i l cc th tinh th huy n ph. Cc h t

ng k t h p v i nhau v d l c.

K c h t c a k t t a b ng b i nh ng thng s th c nghi m n

ha tan c a k t t a, nhi , n ch t t o k t t a v t pha tr

t o nn k t t a. c a qu trnh hnh thnh k t t a hy cn ch

c hi u m .




Cc thng s ny ng th c h gi qua

qu bo ha t i c a h :

qu bo ha t i = S

SQ

Q l n c a m t ch t c th k t t a t dung d ch

ha tan c a k t t a.

Nh ng b ng ch ng th c nghi m ch ra r c h t c a k t t i

ng c v bo ha t i trung bnh trong su t th i gian thu c th c

thm vo. Khi (Q-S)/S l n th k t t a keo hnh thnh cn khi (Q S) nh th k t

t a xu t hi n d ng tinh th .

2.2.1.2. t o thnh k t t a

ng c bo ha t c h t c th c gi i thch

n u ta gi thi t r ng k t t c t o b i hai qu trnh khc nhau:

a) G n t o m m k t tinh

Trong m m k t tinh, m t vi ion, nguyn t ho c phn t (c l b n ho

t p h p v t o m t d ng r n b ng nh ng

c t o trn b m t c a cc ch t nhi m b ng, ch ng h t

b i.

b) G n l n ln c a k t t a

S k t t n s c nh tranh gi a s t o thm m m k t

tinh ho c s l n ln c a cc m m k t tinh c s n.

c h nh b

N u s l n ln chi th m t s ng nh c a cc h c l n

c t o thnh.

c) th s ng m m k t tinh N t l v qu bo ha

i c a dung d ch

Q SN k

S (2.1)




V i k l h s t l

t o k t t a tinh th h nn ti n hnh k t t a trong nh u

ki n th c nghi bo ha t i cng b cng t t.

2.2.1.3. K i m sot th c nghi m c c h t

Cc thng s m lm gi qu bo ha t i d n k t t a

tinh th h t l n t o thnh bao g m:

ha tan c a k t t a.

Dng cc dung d ch long t o k t t gi m Q)

Thm ch m thu c th nng vo v i nhau v khu y tr n m gi m Q

m t th m b t k)

Sau khi k t t a t o thnh nn c th cc k t t a k t tinh l i.

Cc h t l c b i ki ha tan

c a k t t a ph thu pH c a dung d ch.

V d :

Cc k t t a tinh th d l c c c t ng axit v a

ph mu i ha tan nh k t t c hon ton b i thm ch m

dung d th t t c canxi oxalate k t t a

h t.

Khng may, nhi u k t t a khng th c t i d ng tinh th i

nh u ki n th c nghi m th c t ng khi k t t ha tan qu

th p so v i gi tr Q th k t t a keo s xu t hi n.

V d : cc k t t a c a hydroxyt s t, nhm, crm v t a sunfua c a h u h t cc

kim lo i n ng ch d ha tan r t th p c a chng.

2.2.2. K t t a keo

Cc k t t ng b n trong m t th c

s d ng trong cc php phn tch tr ng v cc h t c a n qu nh l c.

Cc h t keo c th lin k t l i v i nhau thnh cc t p l tch kh i dung

d ch v c th l c b y tr n v thm cc ch n li.

2.2.2.1. S c a cc h t keo




Qu trnh lm cc h ng t p h p l i thnh nh ng h t l l c

c g i l s .

Cc h ng b n v chng tch y l n nhau.

n tch ny l do cc cation ho c cc anion lin k t trn b m t c a cc h t

keo.

ng c a cc ion l b h p ph trn b m t ch t r n ion do nh ng l c

lin k ng ch u trch nhi m cho h t l n ln.

V d :

Cc ion b c b m t c a h t AgCl c kh lin k t v i cc ion m do chng

v tr b m t. Cc ion m - trong dung d ch b ht v cc v tr ny b ng

l c ht v i cc ion clorua bn trong m i. Ion clorua trn b m t

c v i cc cation ha tan trong dung d ch.

Lo i v s ion b trn b m t h t c a cc h t keo ph thu c m t cch

ph c t p vo m t s thng s ng h p ph m

lo i tham gia vo thnh ph n k t t a.

V d :

Khi thm t t NaCl vo dung d ch AgNO3 th cc h n tch

+ cn ch h p ph ln b m t h t keo.

Khi k t t a h t Ag+ n u ti p t - th i n tch c a h t keo tr thnh

m do h p ph cc ion Cl-.

S h p ph m c a ion m i l v khi b m t b

ph b i cc ion m i th n tch c a h t keo tr thnh h ng s , c l p

v i n .

Cc ion h p ph trn b m t h t keo t o nn l p h p ph , v d l cc ion

Ag+. Bao quanh h n l m t l p dung d ch, g i l l i ch a

m Cl-. Cc ion b c h p ph v l i t o nn

l n tch kp lm b n cc h t keo ng n l i g n nhau

.

S c a cc h ng x y ra b i:




c bi t l khu y tr n m nh dung d ch.

Thm ch n li thch h n

c n c a m i h t. K t qu l th tch c a dung d ch ch cn

b n tch c a l p h p ph b gi m xu ng. Hi u ng t ng c ng c a

vi c thm m t ch n li l lm co l cc h ti n

l i g n nhau d .

2.2.2.2. S pepti ha

S pepti ha l qu trnh m t k t t chuy c l i v tr ng

u.

Khi m t k t t c r a, m t vi ch n ly ch u trch nhi m cho s

t c a chng b r a gi tch c a l i. Nh ng l y

ch u trch nhi m cho s c thi t l p l i v cc h t b tch l n

nhau. K t qu k t t a b m t do s pepti ha.

V c gi i quy t nh r a k t t a b ng dung d n li m

ch t ny s b c nung nng.

V d : k t t c r a s ch b i dung d ch HNO3 v k t t a khng

b ng do nhi m b n ch t ny v n bay h t t a.

2.2.3. K t t a tinh th

K t t a tinh th ni chung d l c v t b nhi m b t t a keo.

K c c a n c ki

c h t c th c l gi m Q b ng cch s d ng dung

d ch long, thm thu c th ch ng cch k t t a trong dung d ch

u ch ng t o k t t a.

S ha tan k t t a tinh th r i k t tinh l i c t t a tinh th h t l

l

2.3. Hi ng c ng k t

C ng k t l hi ng cc h p ch t ha tan khc b tch t dung d ch v gy

nhi m b n trong su t qu trnh t o k t t a.




Ch l dung d ch khng b bo ha b i cc ch t tham gia c ng k t. S nhi m

b n c a m t k t t a b i m t ch t th hai m tch s ha tan c a n b t th

khng g i l s c ng k t.

C b n lo i c ng k t: h p ph b m t, s t o thnh tinh th h n h p (c ng k t

ng hnh), n i h p v s b c.

Trong khi s h p th b m t v s t o thnh tinh th h n h p l cc qu trnh

cn b ng th n i h p v s b ng h c c a qu trnh l n ln c a

k t t a.

2.3.1. H p ph b m t

2.3.1.1. H p ph l ngu n gy ra nhi m b n chung

V i cc h t keo th s nhi m b do h p ph ln cc din tch b m t

l n c a cc h .

S h p ph c y ra trn b m t tinh th ng c

s ch c a tinh th do di n tch b m i nh c a chng.

S ng t c a cc h t keo khng lm gi s ng h p ph b i v cc

h t b t hy cn c di n tch b m t l n.

Cc ch t nhi m b n do c ng k t trn cc h g m cc ion m i

h p ph t u trn b m , v cc i i b gi trong l p

m ng dung d ch n m st h t. Hi u ng t ng c a hi ng h p ph b m t l

mang theo cc ch t ha tan khc khi b m t b nhi m b n.

V d :

K t t a AgCl trn b nhi m b n do h p ph cc ion Ag+ h p ph cng v i NO3- v

i khc trong l i. K t qu l b c nitrat c ng k t cng v i AgCl.

2.3.1.2. m thi u cc ch t b n h p ph trn h t keo

tinh khi t c a nhi u t c c i thi n. Su t qu

trnh ny, n c b y ra t ch t r cho k t t a l c di n tch b

m t nh lm gi m s h p ph .

R a k t t b ng dung d ch ch a ch n li d t

h u ch b i v nh ng ch c thay th




b i cc ch n li d ba a gi c nhi u cc ion

h p ph b m t b i v l c ht gi a cc ion ny v i b m t c a ch t r n qu

m nh. Tuy nhin c s i x y ra gi a ion trong l i v i cc ion

trong dung dich r a gi i.

Vi c r a k t t a b ng dung d ch axit s chuy n l i ph n l n thnh cc

ion H+. V v y ch cn ion Cl- v H+ b trn l p kp. HCl d

k t t c lm kh.

B t k l, m t k t t lun b nhi m b n m t

m m ch sau khi r a c n th n.

S k t t a l i

M t cch hi u qu gi m thi u ng c a s h p ph l lm k t t a l i

ho c k t t a hai l n. t r l c ha tan l i v cho k t t a l i.

Vi c k t t a l ng mang theo m t ph n ch t nhi m b n hi n di n

u. Khi dung d ch ch a k t t c ha tan s ng

ch t nhi m b i dung d u v th m ch t h p ph

trong su t qu trnh k t t a l n hai.

S k t t a l i t n nhi u th t c n thi t cho nh ng lo i k t t

c nhm v nh ng lo i k t t ng c ng k t

m nh v i nh ng hydrxit kim lo i n m, cadimi v mangan.

2.3.2. S k t t ng hnh

S t o thnh k t t ng hnh khi m t trong cc ion trong m i tinh th b

thay th b i m t ion khc.

i u ki n x y ra:

Hai ion ny ph n tch

K c c a n ch khc nhau khng qu 5%.

2 mu i ph i c cng m t ki u tinh th .

V d : B c t o thnh b i vi c thm bari clorua vo dung d ch ch a

ion sunfat. N u trong dung d ch c m t ch th BaSO4 b nhi m b n m nh b i

PbSO4, th m ch m c d t o thnh ch




sunfat. 2+ thay th m t vi ion Ba2+ trong tinh th bari sunfat.

T MnS trong CdS.

Gi i php:

- N u k t t ng hnh x y ra th vi c tch ion gy ra c c th c hi n

n k t t a cu i cng.

- Nn trnh s d ng nh ng thu c th thm vo c kh ng k t

ng hnh.

2.3.3. S n i h p v s b h c

Khi m t tinh th l n ln nhanh trong su t qu trnh t o thnh k t t a, nh ng ion

l trong l i c th b b

Cn s b c x y ra khi cc tinh th n m g n nhau trong su t qu trnh l n

ln s b y cc ti nh dung d ch trong tinh th .

C hai c th c gi m thi u khi t t o thnh k t t a ch

m nh.

2.4. ng d ng c ng

2.4.1.T ng quan

c p d ng cho nhi

c u ch t trung ha c, SO2, CO2, v iot. R t nhi u cc

ch t h nh b ng

ng. V d a, salixilat trong thu c, nicotin trong thu c tr

su, cholesterol trong ng c, v benzaldehyde trong d ch chi t qu h nh nhn.

B ng sau gi i thi u tm t t m t s ng h ng

ng.

Ch t phn tch Thu c th K t t a t o thnh D ng cn Ba2+ (NH4)2CrO4 BaCrO4 BaCrO4 Pb2+ K2CrO4 PbCrO4 PbCrO4 Ag+ HCl AgCl AgCl Hg2

2+ HCl Hg2Cl2 Hg2Cl2 Al3+ NH3 Al(OH)3 Al2O3 Be2+ NH3 Be(OH)2 BeO




Fe3+ NH3 Fe(OH)3 Fe2O3 Ca2+ (NH4)2C2O4 CaC2O4 CaCO3 ho c CaO Mg2+ (NH4)2HPO4 NH4MgPO4 Mg2P2O7 Zn2+ (NH4)2HPO4 ZnNH4PO4 Zn2P2O7 Ba2+ H2SO4 BaSO4 BaSO4 Sr2+ KH2PO4 SrPO4 SrP2O7

2.4.2. M t s thu c th h

S thu c th h c pht tri ng cc

ch phn thnh hai lo i:

- M t lo i t o nh ng s n ph m khng ion ha tan km g i l cc h p ch t n i

ph c.

- Lo i kia t o nh ng s n ph m t t gi a cc ch i thu c

th l lin k t ion.

Cc thu c th h o nn nh ng h p ch t n i ph c t nh t ph i c hai lo i

nhm ch c. M i lo i ch c c kh t v i m t cation b ng cch cho c p

ng nhm ch nh v trong phn t sao

cho m t vng 5 ho c su nh c t ph n ng. Nh ng thu c th lo i ny

c g i l thu c th chelat v s n ph m c c g i l cc chelat.

Cc chelat kim lo i khng phn c c v k t qu l c kh n a tan

th ng nh ng h p ch t ny

c mu s m v khng ht m nhi th p.

Gi i thi u m t s thu c th h c dng trong phn tch tr ng

8-hydroxyquinoline

X p x kho ng 20 cation t o ph c chelat v i 8-hydroxyquinoline. C u trc c a

magie 8-hidroxyquinoline l tiu bi u cho nh ng chelat ny.

N

OH

+ Mg2+

N

ON

O

Mg + 2H+

2




ha tan c a ph c gi a 8-hidroxyquinolin v i kim lo i trong kho ng

ph i r ng t cation n n cation khc v ph thu pH

b i v 8-hidroxyquinolin lun lun b tch H trong ph n ng t o chelat. V v y, ta

c th c m ch n l trong vi c s d ng 8-hydroxiquinolin

b i ki m soat pH.

Dimetyl glyoxim

L m t thu c th h u o k t t a v ng ki m y u. Ph n

ng x

CH3

CC

H3C

NN

OHHO

CH3

CC

H3C

NN OO

+ Ni2+

H3C

C C

CH3

N NO O

Ni HH + 2H+

2

Thu c th ny to l ch m ng nh c a niken c x l d

dng.

Bi t p

2.1. M t m u qu ng magnetite, Fe3O4, c phn tch b ng cch ha tan 1.5419-g

m u trong dung d ch HCl c. Sau khi thm HNO3 oxi ha Fe2+ to Fe3+ , dung

d ng v c r i thm NH3 k t t a h t Fe(OH)3.

Sauk khi l c v r a, r c 0.8525 g Fe2O3 nguyn ch t. Tnh

% kh ng c a Fe3O4 trong m u.

2.2. L y 0.6113-g m u h p kim ch a Al, Mg, v m t s kim lo em ha tan.

c cho k t t a v i 8- hydroxyquinoline. Sau khi l c, r a v s y

kh th thu c 7.8154 g (C9H6NO)3 v Mg(C9H6NO)2. Cn n ng




t a ny th thu c 1.0022 gam h n h p Al2O3 and MgO. Tnh % kh ng

Al v Mg trong m u h p kim.

2.3. Cn 0.1392 g m t m u Na3PO3 khng tinh khi a tan trong 25 mL

c. Cho t t t ng gi t vo dung d ch u ch t 50 mL dung d ch

HgCl2 3% w/v, 20 mL dung d ch natri acetate 10% w/v v 5 mL acetic acid

. PO33 b oxi ha thnh PO4

3 c k t t a Hg2Cl2. Sau khi l c

r a kt t a Hg2Cl2 c 0.4320 g. Tnh ph ng c a

Na3PO3 trong m u.

2.4. Cn 101.3-mg m u m t h p ch t h t chy trong oxi tinh

khi c thu trong cc ng h p th . ng h p th CO2

kh ng 167.6 mg, v ng h p th H2O t 13.7-mg. M t khc khi cn 121.8

mg m l b ng dung d ch HNO3 t o Cl2, ng v i Ag+, t o

262.7 mg AgCl. nh cng th n nh t c a h p ch t h

C5H2Cl2)

2.5. Cn 26.23-mg m u MgC2O4 H2O c ch i nung nn n kh ng

i 1200 C, c kh ng ch t sau khi nung l 20.98 mg. M t

khc m t m u nguyn ch t MgC2O4 H2O, khi x th y kh ng

i 69.08% so v i kh nh %w/w MgC2O4 H2O trong

m u trn.

2.6. Nhm c th nh b ng nh k t t a Al(OH)3

v chuy n v Al2O3. M t m u c ch a kho ng 0.1 g Al c ha tan trong 200

mL H2O v 5 g NH4Cl v m t vi gi t ch th methyl (methyl pH nh

v c mu vng pH trn 6). Dung d n

si r i thm t ng gi t dung d ch NH3 1:1 cho t i khi dung d ch chuy n sang

c k t t a Al(OH)3. K t t c gi m si c a dung d ch

trong vi pht, l c, v r a b ng dung d ch nng 2% NH4NO3. K t t

10001100 C, t o Al2O3.

a) Hy ch ra 2 cch trong th t c trn gip cho s t c h t

c l




b) c nung ph c ti n hnh c n th Al(OH)3 chuy n ha h t v

Al2O3. N u s chuy n ha khng hon ton th s no k t

k t bo co %w/w c a Al trong m u?

c) NH4Cl v ch th methyl g trong th t c ny?

d) M t th t c khc k t t a nhm v d ng 8-hydroxyquinolate, Al(C9H6ON)3. T i

sao th t c ny thu n l ch tr ng

2.7. nh b ng nh k t t i d ng

CaC2O4 .H2O, n sang d ng CaCO3. Mu c ha

c v 15 mL dung d ch HCl 6 M . Sau khi ha tan, dung d ch

n si v thm dung d ch ammonium oxalate.

Dung d c duy tr 80 C, v thm t ng gi t dung d ch NH3 6 M,

cng v i khu y cho t i khi dung d ch c tnh ki m y k t t a

c v dung d yn t nh t 1 gi . Sauk hi ki m tra k t t a

hon ton, m c, r a b ng dung d ch 0.1% w/v ammonium

oxalate, r i lm kh 100120 C trong 1 gi . K t t c chuy n

thnh CaCO3 trong l nung b ng cch lm kh 500 25 C cho t i kh i

i.

a) T i sao k t t a CaC2O4.H2O c chuy n v d ng CaCO3?

c cu i cng, n u m c nung nhi t qu cao m ng

CaCO3 c th chuy n ha v CaO. ng g n kh t qu bo

co %w/w Ca?

c) T i sao (NH4)2C2O4, thm vo dung d ng axit m khng

ngu ng ki m.

2.8. S t c th nh b ng cch k t t i d ng Fe(OH)3 n

Fe2O3. Cn m u phn tch r i chuy n vo c c c c

v 10 mL dung d ha tan hon ton m u. Oxi ha h t Fe2+ trong

dung d c b ng 1 2 ml dung d ch HNO3 tch

h c pha long ng gi t

dung d ch NH3 1:1 cho t i khi mi c a NH3 nh n r. Dung d ch c ti p t




si trong vi pht n a, k t t l ng xu nh. K t t c l c

r a b ng dung d ch nng 1% w/v NH4NO3 cho t i khi khng cn ion Cl- trong

c r a. Cu i cng, k t t nhi 500550 C n

kh i. Cn Fe2O3 c.

(a) N u vi c nung khng th c hi n u ki O2 th k t t a cu i cng s

chuy n m t ph n thnh Fe3O4. u ny s n k t qu

bo co %w/w Fe?

(b) K t t c r a b ng dung d ch NH4NO3. T i sao NH4NO3 c thm vo

c r a?

(c) T i sao c n thm NH3 n khi c mi r c a kh NH3?

(d) M t lm th ki m tra ion Cl- khng cn trong n c r a?

2.9. ng c a s t v mangan trong m t m u h p kim c th nh b ng

p k t t a v i 8-hydroxyquinoline, C9H7NO. Sau khi cn h n h p k t

t a, k t t a tan v l ng 8-hydroxyquinoline nh

b ng m

Trong m t php phn tch, cn 127.3-mg m u h p kim c ch a s t v mamgan

cng v i cc kim lo a tan trong axit v x nh

ng c a cc kim lo ngan c k t t a Fe(C9H6NO)3 v

Mn(C9H6NO)2, c kh ng t ng c ng l 867.8 mg. ng 8-hydroxyquinoline

trong h n h p k t t a ny l 5.276 mmol. Tnh %w/w Fe v %w/w Mn trong

m u h p kim.




3: AXIT-

A)

3.1. M t vi khi ni m v s chu v n

3.1.1. M t vi khi ni m v s chu

-Dung d ch chu n: l dung d ch ch a thu c th c n bi

th c hi n php chu .

-Php chu c ti n hnh b i thm t t dung d ch chu n t m t buret

vo dung d ch ch a ch t c n phn tch t i khi ph n c cho l x y ra hon

ton.

- c a m t php chu x y ra th ng ch t

chu n t dung d ch chu thm vo ph n ng v chnh xc ng ch t

c s t ng c a ph n ng chu .

m l thuy t m khng th nh b ng th c nghi m.

- m k t thc chu (g i t m cu i) l th m d ng chu

d a vo nh i v u ki n c

M i c g u nh cho s khc nhau v th

tch ho c kh ng gi m cu i l nh . S khc nhau

n sai s chu .

-Ch t ch th l ch c thm vo dung d ch ch a ch t c quan

st s i v t l t ng t c a n g n ho

m s bi i mu s c, s xu t hi n ho c m t mu

- Ch t chu n g c: l nh ng ch t tinh khi t phn tch (99.9%) khng b phn

h y ho c ph n ng v i cc ch t khc c trong khng kh trong qu trnh b o

qu n. N c i b ng v t

c h p th pha cc dung d ch chu n t cc ch t chu n g c, ta cn chng

b ng cn phn tch r i ha tan trong m ng dung d ch c th tch bi c.




-N u dung d ch chu c pha t nh ng ch tinh khi t cao do

qu trnh b o qu n th ta cn l a ch t ny pha trong dung mi

thch h p r i chu n l i dung d pha nh chnh xc n c a n.

-Chu tr c ti p: Dung d ch chu c thm t t vo dung d ch ch a

ch n khi ph n c hon thnh.

-Chu c: Cho m t bi t chnh xc c a dung d ch chu n

th nh t vo ch t phn tch, sau khi ph n ng x y ra hon ton, thm dung d ch

chu n th chu a ch t chu n th nh t.

Chu d m cu i c a php chu c r rng

i chu tr c ti p; ho c do ph n ng tr c ti p x y ra ch m c n ph i

thi t l u ki n (v d ph n ng x y ra hon ton.

3.1.2. N

-N mol(CM) l s mol ch t tan ch a trong 1 lit dung d ch ch a ch t tan

nguyn c a CM l M hay mol/l.

N ng(CN) l s ng gam ch t tan ch a trong 1 lit

dung d ch ch a ch nguyn c a CN ng gam/l.

nh lu ng: Hai ch t A v B ph n ng v v i nhau theo

nh ng s ng gam b ng nhau hay

VA.CN(A) = VBCN(B) (3.1)

V i VA v VB l nh ng th tch dung d tham gia ph n ng

CN(A) v CN(B) l n ng c a dung d ch A v B.

-N ph

Ph kh ng (w/w) = (kh ng ch t tan / kh ng dung d ch)

x 100%

Ph tch (v/v) = (th tch ch t tan / th tch dung d ch) x 100%

Ph ng trn th tch (w/v) =

= (kh ng ch t tan, gam / th tch c a dung d ch, ml) x 100%

-N ph n tri u (parts per million: ppm) (Cppm)

Cppm = (kh ng ch t tan / kh ng dung d ch) x 106 ppm




-N ph n t (parts per billion: ppb) (Cppb)

Cppb = (kh ng ch t tan / kh ng dung d ch) x 109 ppb

3.2. Khi ni php chu axit

axit a trn ph n i proton gi a cc

nh n c a chng.

nh c n: H3O+ + OH- = 2H2O

ng dng dung d ch chu n l cc dung d ch

axit m 2SO4 chu m, NH3, cc mu i

c l i, ng i ta dng cc dung

d ch chu n l cc dung d chu cc axit n 2SO4,

HNO3, cc axit h 3PO4

V cc ch t chu a ph n l n khng th a mn cc

yu c u phn tch, nn c n ph i chu l i b ng cc dung d ch chu n g

Na2B4O7.10H2O, H2C2O4.2H2O.

Trong qu trnh chu pH c a dung d i v khi vng g i m

t ng t gi tr pH c a dung d ch. L i d c

i ta s d ng nh ng ch i theo gi tr pH c a dung

d pht hi

Nh ng ch c g i l cc ch t ch th axit-

3.3. Cc ch t ch th axit-

3.3. nh ngh

Ch t ch th axit- ng l nh ng axit ho

d ng axit v d p c a chng c mu khc nhau. V d , m t ch t

ch th d c m t b i cn b ng sau:

HInd + H2O Ind - + H3O

[tài liệu hóa học chuyên ngành online] hoá học phân tích định lượng lê thị...

Documents