Dinh Luong
Transcript of Dinh Luong
-
8/13/2019 Dinh Luong
1/49
BI GING
HA PHN TCH
-
8/13/2019 Dinh Luong
2/49
1. i cng v phn tch th tch1.1.Bn cht ca phng php
xc nh nng ca mt dung dchcht A(gi l cht nh phn),ngi ta thm
dnmt dung dch cht B(gi l cht chunhay thuc th) bit nng vo mt thtch chnh xc dung dch cht A cho n khi
hai cht phn ng va vi nhau. T th tch dung dch cht B dng tnh
c nng ca dung dch cht A.
-
8/13/2019 Dinh Luong
3/49
5
0
4
0
3
0
2
0
1
0
0
D dich B
D dich A
- Cht A(cht nh phn) lcht cn xc nh nng
- Cht B(cht chun haythuc th) bit nng
- Cho hai cht phn ng va vi nhau vi nhng thtch xc nh
- Da vo nh lut ng
lng tnh nng cadung dch cht A.
-
8/13/2019 Dinh Luong
4/49
Theo nh lut ng lngta c :
VA. NA = VB. NB
NA =
Trong :
VA , VB : l th tch ca
dung dch A v B
NA , NB:l nng nglng ca dung dch
cht A v cht B
A
BB
V
NV .
5
0
4
0
3
0
2
0
1
0
0
D dich B
D dich A
-
8/13/2019 Dinh Luong
5/49
1.2. Nhng khi nim c bn
1.2.1. S chun Qu trnh thm dn dung dch B vo
dung dch A gi l s chun .
1.2.2. im tng ngim tng ng l im m dung
dch cht A phn ng va vi dungdch cht B.
-
8/13/2019 Dinh Luong
6/49
V d : Khi chun HCl bng NaOH :
HCl + NaOH = NaCl + H2O
Khi lng NaOH phn ng ht vi lngHCl th trong dung dch ch c nc vmui NaCl.
Vy im tngng ng vi gi trpH = 7
-
8/13/2019 Dinh Luong
7/49
1.2.3. Cht ch th
pht hin im tng ngtrong phng php phn tch th tchngi ta thng dng nhng cht ch
th khc nhau.Cht ch thl nhng cht c mu
scthay i khi phn ng t n im
tng ng.
-
8/13/2019 Dinh Luong
8/49
1.2.4. im kt thc chun
im m cht ch th gy ra nhngbin i m mt quan st c, cho ta bitphn ng n vng gn im tng
ngth ngng chun c gi lim kt thc.
Ni chung, im kt thc thng khngtrngvi im tng ng. im kt thccng gnvi im tng ng th phpnh lng cng chnh xc.
-
8/13/2019 Dinh Luong
9/49
1.3. Phn loi cc phngphp phn tch th tch
Ty theo bn cht ca phn ng giathuc th v cht nh phn ngi ta chia
thnh cc phng php sau :
1.3.1. Phng php trung ha
Phn ng nh lng l phn ng traoi proton hay phn ng axit - bazHA + BOH = AB + H2O
-
8/13/2019 Dinh Luong
10/49
1.3.2. Phng php oxy ha khPhn ng nh lng l phn ng
trao i electron gia mt cht oxy hav mt cht kh
Ox1 + Kh2 = Kh1 + Ox2
-
8/13/2019 Dinh Luong
11/49
1.3.3. Phng php kt ta
Da vo phn ng kt ta gia thucth v cht cn nh lng to ra mthp cht t tan.
Thng dng nht l phng phpto thnh kt ta bc halogenua
X + Ag+ = AgX
-
8/13/2019 Dinh Luong
12/49
1.3.4. Phng php to phcDa vo phn ng to thnh phc cht
gia thuc th v cht cn nh lng.
Hay dng l phng php to thnh phcvi xyanua v complexon.
Na2H2Y + Men+ = Na2MeY + 2H
+
-
8/13/2019 Dinh Luong
13/49
2. Phng php trung ha
2.1. C s ca phng phpPhng php trung ha l phng php
phn tch nh lng da trn nhng phn
ng cho nhn proton gia axit bazHA + BOH = AB + H2O
-
8/13/2019 Dinh Luong
14/49
Nhn xt :- Trong qa trnh chun , pH ca dung dch
bin i.- Ti im tng ng c s bin i t ngtca pH v ta thu c mt dung dch c pH nhtnhhoc vng axit, hoc trung tnh, hoc
kim.- xc nh im tng ngngi ta phi dng nhng chtch th axit- baz hay gi lcht ch th pH.
-
8/13/2019 Dinh Luong
15/49
2.2. Cht ch th L nhng cht c mu sc thay i theo s bin
i pH ca mi trng.
L nhng cht hu c c tnh axit yu, baz yu .
Trong dung dch c cn bng sau :
HInd + H2O = Ind + H3O +
Ty thuc vo gi tr pH ca dung dch m chtch th dng axit hoc dng baz v mu ca
hai dng ny l khc nhau Khong pH chuyn mu :
pH = pKa(HInd)1 n pKa(HInd)+ 1
(Nng 2 dng axit v baz hn km nhau 10 ln)
-
8/13/2019 Dinh Luong
16/49
Mt s cht ch th thng dng
-
8/13/2019 Dinh Luong
17/49
Yu cu i vi cht ch th
Tan trong nc hoc trong cn nng l 104M n 105M mu phi xut
hin kh r Mu phi chuyn nhanh, r trong mt khong pH
kh hp Khong pH chuyn mu phi gn hoc cha gi
tr pH im tng ng ca phn ng chun( t nht phi nm trong bc nhy ca pH )
Bn vng iu kin thng.
-
8/13/2019 Dinh Luong
18/49
2.3. ng cong chun -Bc nhy pH - Cch chn cht ch th
2.3.1. Kho st ng cong chun axitmnh bng baz mnh
V d :Chun 100 ml dung dch HCl 0,1 N(CA) bng dung dch NaOH 0,1 N (CB).
Phng trnh phn ng :
HCl + NaOH = NaCl + H2O
-
8/13/2019 Dinh Luong
19/49
K tht tin hnhqu trnh nh lng
Buret : Dd NaOH 0,1N
Bnh nn : Dd HCl 0,1N
Tin hnh chun bng
cch nh t t dd NaOHxung bnh nn
Tnh gi tr pH ti tng thiim
Xy dng ng congchun
Chn cht ch th thch hp
5
0
4
0
3
0
2
0
1
0
0
Ddich NaOH 0,1 N
Ddich HCl 0,1N
-
8/13/2019 Dinh Luong
20/49
-
8/13/2019 Dinh Luong
21/49
ng cong nh lng(ng cong chun )
1
7
14
4,3
9,7
pH
V NaOH ( ml )100
-
8/13/2019 Dinh Luong
22/49
NHN XT :
th biu din s thay i gi tr pH cadung dch vo lng NaOH cho vo dungdch HCl, gi l ng cong nh lnghayng cong chun
Trong qu trnh nh lng ban u pH bini t t, gn im tng ng ( khi thiuv tha 0,1 % NaOH ) c s bin i tngt ca pH ( t 4,3 n 9,7 ) gi l bcnhy pHca ng cong chun .
-
8/13/2019 Dinh Luong
23/49
Cch chn cht ch th:
Ba cht ch th phenolphtalein, metyl ,bromotymol xanh, u c khong pHchuyn mu nm trong bc nhycang cong nh lng nn u c thchn c ba cht ch th ny, tuy nhinkhong pH chuyn mu ca bromotymolxanh cha pH ti im tng ngnn
chn cht ch th ny l tt nht v sai sca php chun l nh nht.
-
8/13/2019 Dinh Luong
24/49
2.3.2. Kho st ng congchun axit yu bng baz mnh
V d :
Chun 100 ml dung dch CH3COOH0,1 N ( C
A
) c pKa =4,75 bng dung dchNaOH 0,1 N ( CB)
Phng trnh phn ng :
CH3COOH + NaOH = CH
3COONa + H
2O
Cch tin hnh tng t th nghim trn
-
8/13/2019 Dinh Luong
25/49
-
8/13/2019 Dinh Luong
26/49
CU HI LNG GI
1. Kho st ng biu din nh lng v chncht ch th cho cc trng hp :a . Chun baz mnh NaOH 0,1N bng axit
mnh HCl 0,1Nb . Chun baz yu NH4OH 0,1N (c pKB=4,76) bng axit mnh HCl 0,1N
2. Mt hn hp gm hai axit HCl v CH3COOHcha bit nng . Bng dung dch NaOH 0,1Nv cc cht ch th bit, hy xc nh nng ca tng axit trong hn hp trn.
-
8/13/2019 Dinh Luong
27/49
NH LNGBNG PHNG PHP
OXY HA KH
-
8/13/2019 Dinh Luong
28/49
1. C s ca phng php
1.1. nh ngha
Phng php chun oxy ha - kh
l phng php da trn phn nggia cht oxy ha v cht kh ca haih oxy ha - kh khng lin hp.
Phng trnh phn ng :n2Ox1 + n1Kh2 = n2 Kh1 + n1Ox2
-
8/13/2019 Dinh Luong
29/49
1.2. c im ca phn ngoxy ha - kh :
Xy ra hon ton v theo mt t lng nht nh
Xy ra nhanh, nu chm cn phi tm iu kin
thch hp tng tc ca phn ng ln nhun nng, dng cht xc tc v.v
Phi chn lc, nu trong dung dch chun c
mt cc ion l phi tm cch che hoc tch n ra. Phi c cch v cht ch th thch hp xc nh
c im cui ca qu trnh chun .
-
8/13/2019 Dinh Luong
30/49
1.3. Cht ch th
* Cht ch th loi 1:
L cc cht hu c c tnh cht oxy
ha - kh c mu dng oxy ha v dngkh khc nhau v mu thay i phthuc vo th oxy ha ca dung dch
-
8/13/2019 Dinh Luong
31/49
Qu trnh oxy ha-kh ca cht ch th loi 1c biu din bng phn ng tng qut :
Ind ox + ne = Ind kh
Th oxy ha kh ca h oxy ha kh tnh theophng trnh Nerst :
-
8/13/2019 Dinh Luong
32/49
Mt s cht cht ch th thng dngChtchth Mu
Dngoxy ha DngkhE0(v)Khi [H+] = 1
trung tnh Khng mu + 0,24
Xanh metylen Xanh da tri Khng mu + 0,53
Diphenylamin Tm xanh Khng mu + 0,76
Eric glusin A Khng mu + 1,00
Ax phenylantranilic Tm Khng mu + 1,08
Feroin Xanh da tri + 1,14
-
8/13/2019 Dinh Luong
33/49
* Cht ch th loi 2
L cc cht c kh nng cho php nhn
ra im cui ca s chun , nhngs i mu khng ph thuc vo thca dung dch.
Th d :Dng dung dch KMnO4 chun
cc cht kh nh Fe2+,C2O42 , H2O2v.v, sau im tng ng nu dmt git dung dch KMnO4th dungdch s nhum mu hng.
-
8/13/2019 Dinh Luong
34/49
1.4. ng chun -Cch chn cht ch th
ng chun trong phng php oxyha kh l ng biu din s ph thucth oxy ha (E) ca dung dch vo th tch
(V) ca dung dch chun thm vo. ngchun cho bit bc nhy th ca qutrnh chun , qua s chn c chtch th thch hp cho qu trnh chun .
Mun v ng chun ta phi tnhc th ca dung dch sau mi ln thmthuc th (theo phng trnh Nests).
-
8/13/2019 Dinh Luong
35/49
2. ng dng2.1. Phng php nh lng
bng Iot :Xc nh hmlng Vitamin C
Phng trnh phn ng:
C6H8O6 + I2 C6H6O6 + 2HI
Cch tin hnh
- Buret : Dung dch I2- Bnh nn : Dung dch vitamin C
+ ch th h tinh bt
5
0
4
0
3
0
2
0
1
0
0
Ddich I2
Ddich vitamin C
+ Ho tinh bot
-
8/13/2019 Dinh Luong
36/49
Tin hnh chun cho n khi dung
dch trong bnh nn chuyn t khngmu sang mu xanh nht bn vngc th tch dung dch I2 phn ng.
Tin hnh lm 3 ln, ly kt qu trung bnhv tnh hm lng ca vitamin C ( g/l ).
Bit E vitamin C = 88
Vy :
-
8/13/2019 Dinh Luong
37/49
2.2. Xc nh kh ca nc
Nc trong t nhin ( sng, sui,ao, h... ) ngoi cc tp cht v c cnc nhiu tp cht hu c c ngun gcng vt, thc vt ... Nhng tp chthu c ny c tnh kh v chnh chnggy nn bn ca nc. Thngthng ngi ta hay dng phng
php oxi ha kh hay phng phpthuc tm xc nh kh canc.
-
8/13/2019 Dinh Luong
38/49
Nguyn tc :Dng phng php thatr xc nh lng cht kh.
5
0
4
0
3
0
2
0
1
0
0
Ddich I2
Ddich vitamin C
+ Ho tinh bot
KMnO4
-Nc NC
-H2SO4
-
8/13/2019 Dinh Luong
39/49
-
8/13/2019 Dinh Luong
40/49
PHNG PHP
CHUN TO PHC
-
8/13/2019 Dinh Luong
41/49
Phng php complexon
Da trn s to phc cng cua ca cc ionkim loi vi nhm complexon dn xut caaxt aminopolycacboxylic (ph bin dinatrica axt etylendiamin tetraaxetic - EDTA).
Ch th mu l nhng axt hu c yu hocbaz yu cha nhng nhm mang mu vch mu. Mu ca ch th v mu ca phcphi khc nhau, d phn bit.
pH phi thch hp cho ch th v phn ngto phc xy ra hon ton. Ch th thng dng: eriocromen T,
murexit, xylen da cam
-
8/13/2019 Dinh Luong
42/49
Complexon III (chelaton, trilon B) l
mui dinatri ca EDTA (etylen diamintetra axit axetic)
Vitttl Na2
H2
Y
Trong dung dch complexon III phn lytheo phng trnh sau :
Na2H2Y = 2 Na+ + H2Y
2
-
8/13/2019 Dinh Luong
43/49
Khng ph thuc vo ha tr ca ion kimloi, complexon u phn ng vi ion kimloi theo t l 1:1 theo cc phng trnhphn ng sau :
Men+ + H2Y2= MeY(n 4)+ 2 H+
Me2+ + H2Y2 = MeY2 + 2 H+
Me3+ + H2Y2 = MeY + 2 H+
Me 4+ + H2Y2 = MeY + 2 H+
-
8/13/2019 Dinh Luong
44/49
V d :Ca2+ + H2Y
2 = CaY2 + 2 H+Al3+ + H2Y2
= AlY
+ 2 H+
Th4+ + H2Y2 = ThY + 2 H+
Phn ng gia ion kim loi v complexon
thng gii phng ra ion H+
lm cho pHca dung dch thay i trong qu trnhchun do nh hng nhiu n khnng to phc ca ion kim loi v vy khi
chun phi gi cho pH ca dung dch trong mt khong pH nht nh thch hpcho s to phc, mun vy phi dngdung dch m.
-
8/13/2019 Dinh Luong
45/49
Cht ch th
Dng nhiu nht l cht ch th mu kimloi.
Cht ch th mu kim loi l nhng cht mu
hu c, c kh nng to phc mu vi ccion kim loi v trong nhng iu kin nhtnh mu ca cc phc khc mu cacht ch th t do.
Nhng cht ch th mu kim loi cdng trong chun complexon phi thamn cc iu kin sau:
-
8/13/2019 Dinh Luong
46/49
- Phc ca cht ch th vi ion kim loi phikhng bn bng phc ca complexon vi
ion kim loi.- Mu ca phc gia cht ch th vi ion
kim loi phi khc mu ca cht ch th t
do.- S i mu phi xy ra nhanh v r rt gnim tng ng ca qu trnh chun
- Cht ch th phi c phn ng c trngvi tng ion kim loi.
-
8/13/2019 Dinh Luong
47/49
Cc cht ch th kim loi
Eriocrom T en ( ETOO ) ; Murexit ;
Xylen da cam ; axit sunfosalixilic thy r c ch chuyn mu ca
cht ch th kim loi trong chun complexon ta ly mt v d c th :
chun Mg2 +bng complexon III pH = 11 vi cht ch th l ETOO(k hiu l HInd )
-
8/13/2019 Dinh Luong
48/49
* Trc khi chun :Trong dung dch c ion Mg2+v ETOO
Mg2+
+ HInd = MgInd+
+ H+
xanh nho* Khi chun
Mg2+ + H2Y2 = MgY2 + 2 H+
Khi H2Y2
phn ng ht vi ion Mg2+
tdo, mt git H2Y2 d s phn ng viphc MgInd+ (v phc MgInd+km bnhn phc complexonat magie MgY2 )theo phn ng :
MgInd+ + H2Y2 = MgY2 + HInd + H+ nho xanh
5
0
4
0
3
0
2
0
1
0
0
Ddich I2
Ddich vitamin C
+ Ho tinh bot
- Mg 2+- ETOO
NaH2Y2-
-
8/13/2019 Dinh Luong
49/49
ng dng phng php chun complexon xc nh cng ca nc
cng ton phn ca nc l tngmui canxi v magie tan trong nc.Ta c th xc nh cng ton phnca nc bng complexon III vi chtch th Eriocrom T en.
(Xem THHH i cng)
_______ The End ________