-
BI BO CO TH NGHIM THC HNH HA L
BI 4. HP PH
Danh sch nhm
Tn MSSV
H Hong Long Thnh K39.201.099
Nguyn Thnh Lun K39.106.055
V Hong Xun Nghi K39.106.071
ng Th Thu Tho K39.106.101
Bi Nguyn Minh Hiu K39.106.034
I. MC CH TH NGHIM
1. Kho st s hp th trn ranh gii cc pha rn v lng.
2. Xy dng ng ng nhit hp ph Freundlich, trn c s xc nh cc hng
s
kinh nghim a v n.
II. C S L THUYT
S hp ph l hin tng thay i nng ca cht trn ranh gii pha so vi
trong
lng ca pha. S hp ph ph thuc vo bn cht cht hp ph v cht b hp ph,
ph
thuc vo nhit , vo nng dung dch (nu s hp ph xy ra trong pha lng)
hoc p
sut (nu s hp ph xy ra trong pha kh). Ngi ta phn bit 2 loi lc hp
ph:
Lc c bn cht vt l: lc Van der Waals.
Lc c bn cht ha hc, ch yu biu hin khi s hp ph xy ra trn b mt
cht rn. Khi , gia vt rn v cc phn t b hp ph hnh thnh lin kt
cng ha tr hoc phi tr.
Da vo 2 loi lc hp ph ny, ngi ta chia s hp ph thnh s hp ph vt l v
s
hp ph ha hc. S hp ph vt l t ph thuc vo nhit (nhit hp ph vo
khong
vi chc kJ i vi 1 mol) ; trong khi s hp ph ha hc li ph thuc kh
nhiu vo
nhit (nhit hp ph khong vi trm kJ i vi 1 mol).
Trong s hp ph vt l, qu trnh hp ph c m t 1 cch nh lng bng
phng trnh ng nhit hp ph ca Freundlich:
-
nCam
x 1
trong ,
x l lng cht b hp ph bi 1 cht hp ph c khi lng m v nm cn
bng vi dung dch c nng cht tan C
a v n l nhng hng s c trng cho 1 qu trnh hp ph xc nh.
Nu t m
xln trc tung ; cn trc honh t C, th th thu c l 1 ng cong
(xem Hnh 1).
Thot u, s bin thin ca m
xtheo C hu nh l ng thng, v khu vc nng
nh, m
x t l thun vi C, tc l y n = 1. khu vc nng cao,
m
xt ti gi tr hn,
tc l xy ra s bo ha hon ton, iu ny ng vi trng hp khi ton b b mt
cht
hp ph b bao ph bi cc phn t cht b hp ph. y n
1= 0. Ly logarit phng trnh
ng nhit hp ph ta c:
lgm
x= lga +
n
1lgC
-
th thu c trong h ta (lg m
x theo lgC) s l ng thng (Hnh 2). Da vo
y ta c th xc nh c cc hng s a v n.
Hnh 2. ng nhit hp th dng logarit
III. HNG DN THC HNH
T dung dch CH3COOH 2M pha long thnh cc dung dch c nng v dung
tch
theo bng di y:
Bnh 1 2 3 4 5 6
Th tch dung dch
(ml)
100 100 100 100 100 100
Nng (mol/l) 0.0125 0.025 0.05 0.1 0.2 0.4
c c nng chnh xc ca axit, phi chun dung dch axit va pha
ra bng dung dch NaOH, vi phenolphtalein lm ch th. Mun vy, dng
pipet ly
20ml dung dch axit bnh 1 v 2 ; ly 10ml dung dch bnh 3 v 4 ; v
5ml dung dch
bnh 5 v 6 em chun .
Cn 3g than hot tnh nghin nh v cho vo mi bnh, lc k trong 30 pht.
Lc qua
giy lc. Ly nc lc vi lng nh ln chun trc mi bnh chun axit. Hiu
kt qu gia 2 ln chun (sau khi quy v 100ml dung dch) cho ta lng
axit x b
hp ph bi 3g than trong 100ml dung dch.
-
IV. X L KT QU TH NGHIM
Kt qu th nghim c ghi vo bng sau:
Kt qu cha quy i:
Th tch NaOH 0.1M tiu th chun
axit ban u (ml)
Th tch NaOH 0.1M tiu th chun
axit sau hp ph (ml)
2.5 1.3
4.9 2.5
4.8 2.9
10.1 7.5
10.3 8.2
19.4 16.3
Kt qu quy i:
Th tch
NaOH 0.1M
tiu th
chun
axit ban u (
quy i ra
100ml)
Th tch
NaOH 0.1M
tiu th
chun axit
sau hp ph (
quy i ra
100ml)
x
M (g) C (M) m
x lg
m
x lgC Tnh theo
s ml dd
NaOH
Tnh bng
s gam
axit
12.5 6.5 6 0.036 3 0.0065 0.012 -1.92 -2.19
24.5 12.5 12 0.072 3 0.0125 0.024 -1.62 -1.9
48 29 19 0.114 3 0.029 0.038 -1.42 -1.53
101 75 26 0.156 3 0.075 0.052 -1.28 -1.12
206 164 40 0.24 3 0.164 0.08 -1.09 -0.79
388 326 62 0.372 3 0.326 0.124 -0.91 -0.49
-
th m
x theo C
th lgm
x theo lgC
0
0.02
0.04
0.06
0.08
0.1
0.12
0.14
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35
Hnh 1. ng nhit hp ph x/m
y = 1.7758x + 1.1021
-2.5
-2
-1.5
-1
-0.5
0
-2.5 -2 -1.5 -1 -0.5 0
Hnh 2. ng nhit hp ph dng logarit
C
Log x/m
Log C
-
lgm
x= lga +
n
1lgC
T phng trnh ta c
lga=1.1021 a= 12,65
n
1= 1.7758 n=0,5631
