Giáo Trình Hóa Lý Nâng Cao

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TRNG I HC CNG NGHIP TP.H CH MINH TRUNG TM CNG NGH HA

GIO TRNH THC HNH

HA L NNG CAO

Thnh ph H Ch Minh, thng 6 nm 2006

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Mc lc

Ni dung Trang

BI 1: XC NH ENTAPY CA QU TRNH HA HI CHT LNG. ...... 5

BI 2: TNG IM SI . ............................................................................ 11

BI 3: XC NH NHIT TO THNH CA NC . ................................... 15

BI 4: CN BNG LNG - HI. ...................................................................... 20

BI 5: SC K KH . ........................................................................................... 24

BI 6: XC NH TC PHN NG V NNG LNG HOT HA

CA PHN NG THY PHN CH3COOC2H5 BNG HCl. ......................... 40

BI 7: VN TC PHN NG TH HALOGEN. ............................................. 45

BI 8: DN IN TRONG CHT RN . ................................................... 50

BI 9: PHNG TRNH NERST. .................................................................... 57

PH LC . .........................................................................................................100


Li ni u

Ha l l mt mn hc c s khng th thiu c ca ngnh cng

ngh ha hc.

Gio trnh thc hnh Ha l nng cao c bin son da trn cu

trc chng trnh l thuyt ca mn Ha l 1 v Ha l 2 gm c cc

chng nh sau:

- Nhit ng hc

- Cn bng ha hc

- ng hc

- in ha

C s l thuyt, quy trnh th nghim, tnh ton kt qu v ton b thit

b trong gio trnh ny c trang b t tp on Phywe GMBH (c).

vic thc tp t c kt qu, sinh vin cn phi nghim tc thc hin cc

quy trnh sau:

1. c v nghin cu k bi, hiu cn k cc nguyn l v nhim v

ca tng bi trc khi vo thc tp.

2. Kim tra li h thng lp rp thit b ca bi. Khi c thc mc phi

hi li gio vin hng dn.

3. m bo kt qu o c chnh xc, cc dng c, thit b

trc khi s dng phi c ra sch v sy kh.

4. Khi tin hnh th nghim phi tun th cc iu kin v nhit ,

p sut, tc dng

5. Cc kt qu o c ca th nghim phi c gio vin k xc

nhn trc khi lm bo co.

6. Khng ty sa i cc dy dn, u d hoc s dng my tnh

vo mc ch khc m khng c s ng ca gio vin hng

dn.


7. H thng bi th nghim c s dng p sut, bnh gas, kh nn

cn phi cn thn khi iu chnh van p sut, trnh va chm

mnh, v cc bnh cha kh c th gy tai nn.

8. Tc phong lm vic nghim tc, khng gy n o trong phng th

nghim nh hng n hc tp cng nh cc kt qu o.

Mc d gio trnh v thit b u c chuyn giao t nc ngoi

nhng y l ln bin son v ging dy u tin ti Trng i hc Cng

Nghip Tp.HCM nn chc chn s cn nhiu thiu st. Rt mong c nhn

c s gp ca thy c v cc bn sinh vin gio trnh v phng

php ging dy mn Thc hnh Ha l t kt qu tt hn.

Tc gi bin son

1. L Th Thanh Hng

2. Nguyn Hong Minh

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BI 1: XC NH ENTAPY CA QU TRNH HA HI CHT LNG

1. Khi nim lin quan

Entapy ca qu trnh bay hi, ngng t v thng hoa, p sut hi,

entropy ca qu trnh ha hi, phng trnh Clapeyron - Clausius, quy lut

ca Trouton, nh lut ca nhit ng hc.

2. Nguyn tc

Qu trnh ha hi ca cht lng xy ra khi hp th nhit. xc nh

entapy ca qu trnh ha hi ('H) phi bit khi lng ca cht lng ha

hi. Lng nhit hp th tng ng vi qu trnh ha hi c xc nh

bng nhit lng k.

3. Nhim v

- Xc nh nhit ha hi C2H5COOC2H5OH v CH3OH.

- Tnh ton 'S ca qu trnh ha hi v ng dng quy lut Trouton

tho lun kt qu.

4. Dng c, ha cht v thit b

Hnh 1: S h thng th nghim

5


- Cobra3 unit - Ngun 12V/ 2A - Cp truyn d liu- Mn hnh hin th nhit - Software - u d nhit Pt - Dng c o nhit lng- Bnh bay hi - in tr- Ngun cung cp vn nng- Cp ni, l = 500mm - Bp khuy t- C t- Thanh , l = 500mm - Kp gc phi- Kp vn nng- Chn , h = 500mm - Cn 620g - Cn 3200g - ng h bm giy - Bnh an ton v p k- Bm chn khng bng nc- Erlen 250 ml, c rng - ng cao su, chn khng d = 6mm - ng cao su, d = 6mm - Bp cao su - Kp ng, d = 12 .20mm - Van kim sot khng kh - Xylanh 20 ml - Kim tim, 0.9 x 70mm - Bnh tia - Dietyl ete 250 ml - Metanol 500 ml - Nc ct

12150.00 12151.99 14602.00 12102.00 14503.61 11759.01 04402.00 04405.00 04450.00 13500.93 07361.05 35720.93 35680.04 02022.20 37697.00 37715.00 37692.00 48852.93 48803.93 03071.01 34170.88 02728.00 36134.00 39286.00 39282.00 39275.03 40995.00 37003.00 02591.03 02597.04 33931.00 30007.25 30142.50 31246.81

1 1 1 1 1 1 1 1 1 1 4 1 1 1 3 3 1 1 1 1 1 1 1 1 1 1 5 1 1 1 1 1 1 1


5. Lp t v vn hnh

Lp t dng c nh hnh 1 nhng trong thi gian ny ng ni b

phn gia nhit vo ngun in. Ni u d o nhit vo modul o nhit

T1. Khi ng chng trnh Measure trong Windoows v chn

Temperature nh cng c o. Chn cc thng s o nh hnh 2. Trong

Diagram 1 chn Temperature T0a vi phm vi nhit thch hp v trong

X bounds chn auto range. By gi chun li u d nhit ca bn

trong Calibrate bng cch nhp gi tr nhit c o bng nhit k ri

nhn Calibrate. Sau khi thc hin cc ci t ny, nhn Continue

ghi cc gi tr o. Sp xp cc hin th nh bn mong mun.

t bnh ha hi kh v sch trong bnh erlen v dng ng tim

a 15 ml dung dch s c lm bay hi vo bnh thng qua mt ng

thng t nm bn trong bnh. Ni ng kh vo vi van iu khin khng kh

bng ng cao su di 5 cm. ng ng kh thot ra bn phi bng nt cao su

trnh tht thot cht trong qu trnh bay hi. xc nh khi lng ca

bnh ha hi cn chun b cn c chnh xc 0,0001g. Bnh erlen ch n

thun l dng c h tr cho bnh ha hi.

Cho 900g nc ct ( nhit phng, cn chnh xc 0,1g) vo bnh o

nhit lng, cho c t hnh oval vo bnh sau bt bp khuy t nh hnh

1 (khng c bt ngun gia nhit).

Cho b phn gia nhit, u d nhit v bnh bay hi vo trong bnh

o nhit lng, c nh v tr ca chng. Tho nt cao su ra v ni bnh ha

hi vi bm chn khng bng nc thng qua bnh an ton. Ch n khi

nhit cn bng khong 10 pht. Bt u o bng cch nhn nt . Ch nhit trong bnh o nhit lng n nh hoc giao

ng khng ng k, m bm chn khng v cn thn m van iu khin

khng kh qu trnh bay hi xy ra. Tuy nhin khng nn m qu ln to

ra qu trnh sc kh mnh lit l nguyn nhn tr hon qu trnh si. Khi

nhit ca nc gim xp x 10C (qu trnh bay hi cn phi c thc

hin hon ton) ng van iu khin khng kh v tt bm chn khng.

Ngay lp tc tho ng cao su ca bm u ca bnh bay hi v thay vo

l nt cao su.

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Tip tc o v ghi li nhit ca h thng cho n khi cn bng mi

c thit lp hay nhit ch dao ng xung quanh mt gi tr.

Tip theo xc nh tng nhit lng ca nhit lng k. lm iu

ny ta phi cung cp ngun mt chiu 10V. Nhn nt sau cm

u t do ca ng xon gia nhit vo ngun cung cp in. Lc ny h

thng lin tc b t nng v lng nhit cung cp c o. Khi nhit

ca nc tng tr li v xp x nhit ban u trc khi bay hi (ng h

hin th gi tr nng lng khng nn vt qu 9000 Ws), tt nhit bng

cch nhn nt trn b ngun, nng lng in c hin th chnh

xc trn mn hnh b ngun. Tip tc o thm 3 pht na, sau ngng

lu nhit bng cch nhn nt .

Hnh 3, biu din th ca qu trnh o bng chng trnh

measurement khi ngng vic o lng. Nu bn s dng chc nng

t thanh cng c bn c th c c nhng s liu nhit

khc nhau. Lun lun lm sch v kh bnh cha cht bay hi trc khi

thc hin mt qu trnh o lng mi.

Hnh 2: Thng s o lng

8

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Hnh 3: ng cong thi gian v nhit

6. L thuyt

Khi cht lng c gia nhit p sut khng i (ng p) n nhit

no vt cht s chuyn t pha lng sang pha hi. Nhit si vn

khng thay i khi c s b sung thm nhit cho n khi cht lng chuyn

ht thnh hi. Nu 1 mol cht lng bay hi, th entapy H tng ln do qu

trnh hp th nhit Qv. S chnh lch entapy ny c nh ngha l entapy

ca qu trnh bay hi ('H) v c gii thch bng nng lng cn ph

v cc lin kt trong phn t ca cht lng. S thay i lin tc ca p sut

hi s c tc dng chng li p sut bn ngoi. Nu hi c lm lnh, qu

trnh ngng t xy ra cng nhit , gi l qu trnh thun nghch. Do ,

vic tng ln ca entropy 'S v s ph thuc ca nhit ha hi c th p

dng cng thc tnh theo nguyn l 2 ca nhit ng hc:

vTH S (1)

i vi hu ht cc cht lng th ha hi ('S) thng nm trong phm

vi t 80 n 90 J.mol-1.K-1. Nguyn tc ny c t tn l Trouton c gi tr

c bit cho nhng cht lng khng lin kt.

Trong th nghim ny th nhit ha hi ca cht lng thp hn nhit

si ca n. Trong cch lm ny, cn bng gia pha lng v pha hi b

xo trn bng cch loi b lin tc thnh phn ca pha kh. Nhit ha hi

c tnh theo cc cng thc sau :

9

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'H = 'S.Tv (1.1)

nh H ('h = - Qv) (2)

'h = - Ck. 'Tv (3)

Wel= Ck. 'Tel (4)

el

elk T

WC

' (4.1)

mMT.CH vk u ' (5)

mM

TT

WHel

vel uu (5.1)

Trong :

'TV: Chnh lch nhit ca nc trong sut qu trnh bay hi.

'Tel : Chnh lch nhit ca nc trong qu trnh cung cp in th.

Wel : Nhit lng cung cp to ra chnh lch nhit 'Tel.

Ck: Nhit dung ring ca dng c o nhit lng.

n : s mol cht bay hi.

10

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BI 2: TNG IM SI

1. Khi nim lin quan

nh lut Raoults, Henrys, hng s nghim si, phng trinh Gibbs -

Hemholtz,

2. Nguyn l

Nhit si ca dung dch lun lun cao hn nhit si ca dung

mi nguyn cht. Nhit si ca dung dch ph thuc nng ca cht

tan. Vic o tng im si ca nc c th xc nh c khi lng

phn t ca cht tan.

3. Nhim v

- Lp bng o s gia tng nhit si ca nc ph thuc v nng

ca mui, ur v hydroquinone.

- Thit lp mi quan h gia tng im si v s vin cht tan cho

vo.

- Xc nh phn t lng ca cht tan thng qua mi lin h gia s

tng nhit si v nng .


11



- Dng c o tng im si- Mn hnh hin th nhit - u d nhit - B iu khin tc un- Bp un- Bnh cu 250ml - Becher 250ml - u ni, GL 25/8 - ng silicon - Chn - Kp gc phi- Ngm kp- Ci v chy - pinchcock - Mung cc nh- Dng c p vin - Cn - Da cn - Phu- Pipet - Bp cao su - NaCl 500g - Ur tinh khit- Hydroquinone 250g - Glycerine, 250ml - Nc ct, 5l

36820.00 13617.93 11759.04 47557.01 32247.93 35812.15 36004.00 41242.03 39296.00 37694.00 37697.00 37715.00 32604.00 43631.15 33393.00 04403.04 48852.93 45019.05 34459.00 36590.00 39275.03 30155.50 30086.25 30089.25 30084.25 31246.81

1 1 1 1 1 1 1 1 1 1 3 3 3 1 1 1 1 1 1 1 1 1 1 1 1 1

5. Lp t v vn hnh

Lp t dung c nh hnh 1.

Sy kh v cn bnh bn trong, ghi khi lng (m1). t bnh trong vo

trong bnh ngoi sao cho khe h ca ng nh bn trong nm bn di ca

khp ni bng cao su silicon. Trong sut qu trnh o, hi nc i vo bnh

trong thng qua l bn di, nhng khng c ph ln bnh trong.


Cho vo bnh cu 150 - 200 ml nc, ri ni chng vi cc b phn

lp rp. Ni hai ng silicon vo hai li ra ca bnh ngoi v t 2 u ng

vo gia beacher 250 ml. Gn kp (pinchcock) vo ng thp hn dn ra t

bnh ngoi nhng lc ny cha kha li.

Cho vo bnh trong 40ml nc. ng bnh pha bn trn bng cch

t c nh u d nhit . Cht tan phi c kim tra v nn thnh vin

truc khi cho vo bnh trong (trnh chng dnh vo thnh bnh). Cn 5

mu mi cht (NaCl, Ur, Hydroquinone), mi mu xp x 700mg. u tin

nghin cc cht thnh bt bng chy v ci. Dng b nn, nn chng thnh

vin. Cn vin va nn vi chnh xc 1mg. Gia nhit cho dung mi trong

bnh cu si ln. Hi dung mi i vo bnh ngoi v gia nhit cho bnh trong.

iu chnh tc gia nhit bng b phn iu chnh ngun. Nhit ca

bnh trong c hin th trn mn hnh (oC). Sau vi pht khi m nhit

trong bnh trong gn t n nhit si v khng cn tng c na, h

thp bp un cho n khi ngng si v bt u s ngng t hi t bnh

ngoi vo tr li bnh cu. Sau nng bp un ln li. Khi m qu trnh si

tr li ban u th ng pinchcock. Ci t nhit bng cch nhn nt

o s thay i nhit . vic o c tt hn th s

chnh lch gia hai ga tr trn mn hnh khng qu 0,01K. Ch cho gi tr

hin th n nh. Cn thn m np bnh trong, thm vin u tin ca cht

tan ri ng li ngay lp tc. Ban u nhit gim nh sau tng tr li

trong lc cht tan s tan ra. Khi gi tr hin th tr li n nh, ghi li kt

qu v lp li qu trnh trn cho nhng vin k tip, qu trnh kt thc sau 5

ln o. Th nghim kt thc, u tin m pinchcock, tt bp un. iu quan

trng trnh cho dung dch bnh trong b tro xung bnh cu trong khi nhit

h xung. Ly bnh trong ra, lm kh b mt ngoi, ly u d nhit

ra khi bnh trong v cn li n (m2). Khi lng ca nc lc ny s bng

vi gi tr ca ln o c cui cng tr i khi lng ca bnh trng (m1)

v khi lng ca 5 vin cht tan. th th hin tng im si theo t

s khi lng ca cht tan v khi lng ca nc nh hnh 2.

6. L thuyt

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Dung dch l cht lng bao gm dung mi v cht tan. Ch c dung mi

c th bay hi, p sut hi ca cht tan thc t l bng khng. Vo nm

1886, Raoul a ra nh lut ly chnh tn ng ta: p sut hi ca dung

dch chnh l p sut hi ca dung mi nguyn cht vi phn mol ca dung

mi.

021

2s P nn

nP u

Trong :

PS :p sut hi ca dung dch.

P0: p sut hi ca dung mi nguyn cht.

n1,n2: s mol ca dung mi v cht tan.

Hnh 2: tng im si ph thuc vo nng

0SS T TT

Trong :

TS: nhit si dung dch.

T0: nhit si dung mi.

dm ct

ct S

.m M.1000 .mK

T

mct: khi lng dung mi nguyn cht.

mdm: khi lng cht tan.

Mct: khi lng mol cht tan.

Ks: hng s nghim si

14


BI 3: XC NH NHIT TO THNH CA NC

1. Khi nim lin quan

Nguyn l 1 nhit ng hc, nhit ha hc, nhit lng, entapy to

thnh, entapy ca phn ng.

2. Nguyn l

Entapy to thnh iu kin tiu chun c lp thnh bng tnh

ton entapy ca phn ng. Chng c nh ngha nh l nhit phn ng

to thnh mt mol cht t cc n cht p sut khng i.

phn ng to thnh din ra mt cch t nhin v nh lng c

th entapy tiu chun c th o c trc tip bng nhit lng k. V d

s to thnh nc t oxy v hydro.

3. Nhim v

Xc nh entapy to thnh ca nc bng cch t 100ml H2 trong

dng c o nhit lng bng thy tinh c ng kn.


- Ngun cung cp in th 0 10 KV

- Dy ni 1m

- ng bao thy tinh

- Clorimeter

- Xy lanh 100 ml (3 ci)

- ng Silicon

- hnh ch H

- Thanh thp 250mm

- Thanh thp 500mm

- Thanh thp 750mm

- Dng c o nhit v p sut

- Nhit k -10.+500C (2 ci)

13670.93

07367.00

02615.00

02615.01

02617.00

39296.00

02009.55

02031.00

02032.00

02033.00

87997.01

38034.00

1

2

1

1

3

1

1

2

1

1

1

2


- Knh lp

- C t

64598.00

64598.00

1

1

- Thanh nam chm

- Phu

- Ca nha 1 lit

- Cn

- Bnh kh hydro

- Bnh kh Oxy

- Van gim p cho kh oxy

- Hai ng thp hnh tr

- ng cao su

- Nc ct

46299.02

34457.00

36640.00

48852.93

41775.00

41778.00

33482.00

41774.00

39282.00

31246.81

1

1

1

1

1

1

1

2

5. Lp t v vn hnh

Lp t dng c nh hnh v:

t dng c o nhit lng vo ng bc thy tinh nh c m t

trong ti liu hng dn. t np dng c o nhit lng vo khp ni. Np

ca dng c o nhit lng c hai ng mao dn c b cong cc gc

bn phi ging nh cc ng dn kh, mt trong hai ng mao dn c

lp kht bng hai in cc platin. ng mao dn c in cc platin lun lun

phi nm bn di khi dng c o nhit lng lp t xong.

Cho nc vo ng ong xp x 500g, ri xc nh khi lng ca n

bng cn (m1). Cn thn nc vo ng bao ca dng c o nhit lng

thng qua 1 trong 2 ng ng pha trn ca dng c o nhit lng (bng

phu), ri cn li khi lng ca ng ong (m2). Tnh khi lng mH2O = m1- m2.

Cho c t vo ng bc bn ngoi ca dng c o nhit lng, cm

nhit k vo 2 ng ng ca ng ny. Ni dng c o nhit lng vi 3 xi

lanh kh bng van ba chiu v cn thn ni 2 u ng thy tinh bng ng

cao su silicon ngn. iu chnh cc nt dng ca gi xylanh sao cho th

tch ca n l 100ml.

Ni in cc ca dng c o nhit lng n b phn cung cp in

th bng cp ni. Bt ngun ca thit b cung cp in th, chc chn rng

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cc tia in lin tc phng ra ti cc in cc. Bc kim tra ny rt quan

trng v trong sut qu trnh chy ca hydro cc tia la lin tc lm tng

nguy c n do hnh thnh hn hp n ca kh oxyhydrogen.


Xoay kha ba chiu v tr m, lm y xi lanh kh n 100ml kh oxy

t bnh cha kh (ch xylanh cha oxy nm pha trn bn phi ca dng

c o nhit lng). Xoay kha ba chiu sao cho xi lanh ni trc tip vi

xylanh bn tay tri nm bn kia ca dng c o nhit lng ri bm kh

ti lui vi ln. Trong sut giai on ny oxy c trn ln vi khng kh

trong dng c o nhit lng cng lc s kn ca dng c o nhit

lng s c kim tra (bng cch kim tra th tch kh ca xylanh bn tay

tri v tay phi phi bng nhau). Rt tr li 100ml hn hp kh oxy v khng

kh vo xylanh pha trn bn tay phi t dng c o nhit lng v m bnh

o nhit lng. Lm y xylanh pha di bn tay phi bng 100ml kh

hydro ri ng van li.

Ghi nhit ban u ca nc (T1). Bt ngun cung cp in th, m

kho ba chiu ca xylanh cha kh hydro v n cng lc hai pittng ca 2

xylanh trn v di a kh oxy v hydro vo dng c o nhit lng (trong

khong thi gian 4 - 5 giy) cho n khi c hai xylanh u ht kh hon

ton.

17

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Kh hydro vo trong dng c o nhit lng c t chy bng cc

tia la v chy to thnh nc. Hn hp kh oxy v khng kh cn d s

thu c trong xylanh bn pha tay tri. Sau khi chy, ng ngay lp tc

van ca xylanh cha hydro v tt ngun in. Khuy nc trong ng bc

bng cch di chuyn thanh nam chm qua li cho n khi nhit cn bng

(nhit trn hai nhit k nh nhau). Ghi li nhit ny (T2), T2 nn cao

hn nhit T1 khong 0,5 . Ch ghi nhit phng (T0), p sut kh

quyn (P) trn mn hnh LCD.

6. L thuyt

Nhit to thnh ca nc ('H) c nh ngha nh s thay i

entapy 'h ca mt mol cht v chuyn ha '[ theo phn ng.

H2O + 1/2O2 = H2O

T p,h H

S thay i entapy ('h) ca h thng phn ng xy ra y tng

ng vi nhit c hp th bi dng c o nhit lng (Qcal) ta c phng

trnh:

- T C.c mT cm Qh cal OH OHi ical 22 Trong :

O H2m : khi lng ca nc trong dng c o nhit lng

O H2C : nhit dung ring ca nc (= 4,1868 J.g-1.K-1)

Ccal: nhit dung ca dng c o nhit lng (= 410 J.K-1)

'T = T2 - T1 (K)

Mt khc ta c:

[Hn 2: s mol H 2H n 2

p dng phng trnh trng thi kh l tng:

RTPV Hn 2

Trong :

P: l p sut kh quyn (N.m2)

18


V: l th tch kh H2 (m3)

T: nhit phng

R: l hng s kh (= 8,314 J.mol-1.K-1)

S mol H2 trong 100ml kh (n = 4,065 mol) nhit T = 296,5K v p

sut l P = 100,1 KPa, 'T = 0,45K. Kt qu l nhit to thnh ca phn

ng l -277,1 KJ.mol-1 (gi tr = - 286 KJ.mol-1).

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BI 4: CN BNG LNG - HI

1. Khi nim lin quan

Entropy v entanpy ca qu trnh ha hi, p sut hi, phng trnh

Clapeyron-Clausius, qui tc Trouton - Pictec, nguyn l nhit ng hc.

2. Nguyn l

cc nhit khc nhau, p sut ring phn ca pha kh c to ra

do cht lng bay hi cng khc nhau. Nu p sut trn b mt cht lng

gim, cn bng lng hi c thit lp li bi s bay hi mt phn ca pha

lng.

3. Nhim v

Xc nh nhit ha hi ca aceton bng cch o p sut hi ti cc

nhit khc nhau.



- Dng c o nhit lng

- Mn hnh hin th nhit

04402.00

13617.93

1

1

20


- u d nhit Pt

- ng bo v u d

- Barometer

- u d p sut

- Vng m silicon d = 7mm

- Vng m silicon d = 2mm

- Chn ng h = 750mm

- Kp gc phi

- Bnh cu 3 c

- ng thy tinh thng l = 80mm

- Van mt chiu

- Bnh an ton v manometer

- Bm chn khng bng nc

- ng cao su, chn khng d = 6mm

- ng ong 50 ml

- Phu

- Ca nha 1 lit

11759.01

11762.05

07136.00

07136.01

39296.00

39298.00

37694.00

37697.00

35677.15

36701.65

36705.00

34170.88

02728.00

39286.00

36632.00

34457.00

36640.00

2

1

1

1

1

1

2

3

1

1

1

1

1

3

1

1

1

- Pipet

- Bp cao su

- Acetone 250 ml

- Gyxrin 250 ml

- Mui 500g

- Nc

36590.00

39275.03

30004.25

30084.25

30155.50

1

1

1

1

1

5. Lp t v vn hnh

Lp t dng c nh hnh v. Lp vo bnh cu 3 c mt van mt

chiu, mt ng thy tinh ngn, thng v ng bc ngoi bo v u d nhit

nh sau: thay 2 ming m GL 25/12 bng 2 ming m GL 25/8. C

nh ng thy tinh ngn gia c ca bnh cu. Ni ng thy tinh ny vi

adapter bng mt ng silicon nh (d = 7 mm), sau ln lt ni vi u

d p sut ca thit b o vi mt ng mng ( d = 2 mm). Ni van mt chiu

vi ng cao su n bnh an ton c ni vi bm. Cho 3 git aceton

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vo bnh bo v bc ngoi tn dng s truyn nhit sau nhng u

d nhit ngp trong ng bc ngoi.

Cho vo dng c o nhit lng hn hp sinh hn (nc + mui),

o nhit ca hn hp sinh hn bng u d nhit . Cho vo bnh cu

ba c 50ml aceton, nhng khng nhng chm vo hn hp sinh hn. Lp

bm chn khng bng nc v vn hnh to chn khng trong bnh

cu cho n khi aceton bt u si. ng van trn bnh cu, h bnh cu

ngm vo hn hp sinh hn. Ngay khi nhit h di -50C, m li van

mt chiu lng kh tha di chuyn khi bnh cu. Khi p sut xp x 50

hPa (5000 Pa), kha van mt chiu v cn thn m van ba chiu trn bnh

an ton khng kh t t i vo. Tt bm chn khng, c p sut trong

bnh cu c hin th trn p k. Trong vng 10 pht n c th tng ti a

l 2 hPa. (Nn kim tra li cc ch ni). Gia tng nhit trong bnh cu

tng bc t 2 - 30C bng cch thm nc vo hn hp sinh hn (dng

a khuy u hn hp) hoc ly bt nc mui ra khi bnh o nhit

lng. Sau mi ln tng nhit , ch cho n khi cn bng lng hi

c thit lp tr li, ghi nhn nhit v p sut hi tng ng ca

aceton trong bnh cu. Tip tc th nghim cho n khi nhit t 200C v

cho cn thn khng kh vo bng cch m t t kha van mt chiu trn

bnh cu.

6. L thuyt

p sut hi ph thuc vo nhit v c m t bng phng trnh

Clapeyron - Clausius:

)VT(VH

dTdP

lg

V

Trong :

P: p sut hi

HV: entapy ca qu trnh bay hi

Vg, Vl: th tch ca pha kh v pha lng

T: nhit (0K)

Kt hp vi phng trnh trng thi kh l tng ta c:

22

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2 V

RTH

dTdP

P1

2 V

TdT

RH

PdP

C RTH

lnP V

C: hng s tch phn

Hoc:

12

V

1

2

T1

T1

RH

PP ln

Hnh 2: th hm s

T1 flnP

23


BI 5: SC K KH

1. Khi nim lin quan

Sc k, sc ph, phng trnh Nernsts v s phn b (s lng a l

thuyt), u d dn nhit.

2. Nguyn tc

Qui trnh sc k cho php tch mt hn hp cc cht vi s c mt

ca pha tnh v pha ng.Trong sc k kh pha ng l kh. Pha ng s

chuyn hn hp cc cht qua ct tch vi tc dng khng i. Cn bng

c thit lp gia pha tnh v cc cht khc nhau do vn tc di chuyn

khc nhau ca cc cu t (cn bng ca s phn b, qu trnh hp th, gii

hp th).

cui ct c mt u d, u d ny c th xc nh c nhng

cht khc nhau da trn s khc nhau v tnh dn nhit. Tn hiu ca u

d pht ra l hm s theo thi gian (sc ph)

S dn nhit khc nhau ca kh mang v cc cht gy ra s bin i

ca u d, u d ny c t ti mch cu Wheatstone. Tn hiu in i

ra c ghi li ra giy v l mt hm theo thi gian (sc ph).

3. Nhim v

- Xc nh thi gian lu ca nhng cht khc nhau v biu din s

tch sc k ca hn hp kh butane.

- Tch v nhn bit thnh phn ca hn hp 2 thnh phn gm

ethanol v ethylacetat.


- Cobra3 unit - Ngun cung cp 12V/2A - Cp truyn d liu- Software - Dy ni, l = 250mm mu

12153.00 12151.99 14602.00 14520.61 07360.01

1 1 1 1 1


- Dy ni, l = 250mm mu xanh - B phn iu khin sc k - u d sc k - ng bao bng thy tinh - Ct tch sc k - Nt cao su - o lu lng bng bt x phng - Chn hnh ch H - Thanh , l = 750mm - Kp gc phi- Kp vn nng- Xylanh 10 Pl- Xylanh 1 ml - Kim tim, 0.45 x 12mm - ng thy tinh, thng l = 80 mm - Nhit k -101000C - ng h bm giy - Bnh kh Heli - Chn bnh kh He - Van gim p- B phn gia nhit, 1000C- B phn ci t ca b iu nhit- B iu nhit dung tch 6l - ng cao su, chn khng - ng cao su - Kp ng d = 812mm - Kp ng d = 1220mm - Cn - Bnh cu 500ml - Bm chn khng bng nc- Bnh bo v vi p k- Mung- Phu thy tinh - Bp cao su - Becher 150ml - Van chnh tinh - Kh nn n-butan - Kh nn iso-butan - Bng thy tinh - Chromosorb - Dinonylphthalate

07360.04 36670.99 36670.10 02615.00 36670.00 02615.03 36675.00 02009.55 37692.00 37697.00 37715.00 02607.00 02593.03 02598.04 36701.65 38056.00 03071.01 41776.00 41774.00 33481.00 08492.93 08492.01 08487.02 39286.00 39282.00 40995.01 40996.01 48852.93 35862.00 02728.00 34170.88 33398.00 34457.00 39275.03 36003.00 33499.00 41773.11 41773.12 31773.03 31514.04 31276.10

1 1 1 1 1 1 1 1 2 6 6 1 1 1 1 1 1 1 1 1 1 1 1 2 6 7 2 1

http://hoahocsp.tk

- Acetone 250ml- Ru etylic tuyt i 500ml - Etylacetat 250ml- Nc ct 5l- Dung dch x phng

30004.25 30008.50 30075.25 31246.81


5. Lp t v vn hnh

Chun b th nghim nh hnh 1.

Chun b pha tnh cho ct tch kh bng cch rt aceton vo 10g

Chromosorb trong bnh y trn cho ti khi c mt lp mng cht lng

pha trn Chromosorb. Thm vo bnh cu trn mt dung dch gm 1,11g

dinonylphthalate v 10ml dung dch acetone, lc mnh hn hp trong vi

pht. t bnh trong mt a ng nc m v s dng bm chn khng

bng nc lm gim p sut trong bnh, lc ny acetone bt u si

nh. Ch , gn tephlon xung quanh c bnh cu.

thu hi acetone, ta t thm mt bnh an ton vo gia bnh cu v

bm chn khng bng nc. Trong sut qu trnh bay hi ca aceton, ta

thng xuyn lc bnh cu cho n khi Chromosorb kh li v chuyn mu

sng ln ging vi mu Chromosorb ban u. Khi acetone bay hi ht,

thu gom acetone t bnh an ton vo bnh thu hi cha cc dung mi hu

c. Sau sy Chromosorb 1000C trong vng t 5 - 6 gi. Mt iu ht

26

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sc quan trng l pha tnh trong ct sc k phi kh ro hon ton v khng

c bt k d l mt lng nh dung mi.

pha tnh chun b vo ct bng cch s dng phu v bm chn

khng bng nc. lm c iu ngi ta dng mt que nh y

bng thy tinh vo mt u ca ct tch. Sau , ni u ng thy tinh vo

bm chn khng bng ng cao su v ht kh t ct. Lc ny mt tay gi ct

v nghing sao cho phu c gi u ni thy tinh GL18 (u cn li).

pha tnh chun b v chia thnh nhiu phn cho vo phu, ngay lp

tc n s c ht ngay vo trong ct bng lung khng kh. Cn thn gi

ng thy tinh bng tay kia.Ta phi chc chn rng ct phi c u.

Khi ct y ta ng u cn li bng bng thy tinh nhng thc hin cho

u kia. Tuy nhin khng c n qu cht, nu khng tr lc ca dng kh

vn chuyn trong ct tch qu cao khi ct i vo hot ng. Mt khc chng

phi chc chn ngn khng kh mang to p lc y pha tnh ra

khi ct.

Hnh 2: Cu to ca h thng sc k

Lp t ct tch vo trong ng bao thy tinh iu nhit v t chng

v tr thng ng bng hai kp thng nm bn tri thanh . Sau ni

vi b iu nhit tun hon nm trong b ln bng nha v c th tch l 6l

(b iu nhit ), vi ng bao thy tinh bn ngoi bng ng cao su sao cho

nc vo ng bao thy tinh bn ngoi t pha di. Dng nc chy xung

quanh ct tch v ra ngoi bng mt ng gn nh ct tch.

27


t mt nhit k vo ng thy tinh hnh ng ca ng bao thy tinh bn

ngoi kim tra nhit . Trc khi ci t, cn phi kim tra h thng

tun hon nc (t b phn iu nhit n ct sc k v ngc li) kim

tra h thng ng thi lm y nc trong ng bao thy tinh bn ngoi

(trnh to thnh nhiu bt kh). Trong khi lm vic ny, ta kim tra cc l r

r trong h thng nc tun hon v loi chng ra nu cn thit. Nu ci t

phn ny hot ng ng ta ci t phn cn li ca thit b th nghim theo

chui sau y:

Ni ng chu p lc t bnh kh He n ng ni thy tinh (1). Do ng

ny phi chu p lc cao trong sut qu trnh th nghim nn hai u phi

c sit cht bng bng cc kp ng.

t u d (5) vo bn trong u ni thy tinh (2) v gi cht bng kp

ng. Kt ni u d thng qua ng thy tinh hnh ng (6) c ni vi dng c

o bt x phng, trong c sn 1 n 2 ml dung dch x phng. Ta c

th thng xuyn thm mt lng nh dung dch x phng vo lu lng

kh thng qua bp cao su. Bt x phng c to thnh theo cch ny c

th d dng quan st cho vic o vn tc dng kh.

Ni u d vi b phn iu khin sc k kh, m n ng vai tr cung

cp ngun in v hiu chnh u d thng qua dy cp ng trc.

Cn thn: Ch m b phn iu khin khi c kh di chuyn qua trnh lm h u d do qu nhit.

Ni Cobra3 Chem - Unit vo cm ca b iu khin. lm iu

ny, s dng hai cp ni ni b phn ghi ca thit b iu khin vo thit

b Chem - Unit chanel Analog In. Ni Chem - Unit vo u vo ca my tnh

bng si dy truyn d liu.

Lp mt np cao su kn trn ming ng tim ca ct tch thy tinh nh

l septum. Bt h thng iu nhit vi bm tun hon. nhit phng th

va tch kh, nhng ni chung ta cn nhit cao hn khi tch hn

hp cht lng.

Khi nhit t n ngng cn thit lc ny ta mi cho kh (He)

t t vo ct tch. iu chnh tc dng kh bng van gim p trn bnh

cha He khong 30 ml/pht (o bng dng c o bt x phng). o vn tc

ca bt x phng nh sau:

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Hnh 3: Dng c ly kh

n vo bu cao su c cha 2 ml dung dch x phng to mt t bt

x phng phn trn ca ng thy tinh. Kh i vo mang theo bong bng

ln trn ng. o thi gian mt bt bong bng i t im mc 0 n mc 5

hoc mc 10ml bng ng h bm giy. Tnh vn tc dng kh (ml/pht) t

gi tr ny. V d khi mt bt x phng ti mc 10 ml trong 15 giy, ta o

vn tc kh trong ct tch l 40 ml/pht.

y nc vo erlen c nhm. Ni ng thy tinh trn erlen vi bnh

kh (n-butane, iso butane, camping gas) bng ng cao su di. M van

kh i vo erlen, n to p lc y nc i vo phu nha gn pha trn

erlen. Sau khi y, ng ng vi nt y cao su. ngn khng cho kh b

p ra ngoi erlen do p sut ca nc tc ng ln n y phu bng nt

cao su. Nt ny s c ly ra sau .

6. Qui trnh

6.1. Tch v xc nh ng phn ca butan

Qu trnh tch hn hp butan c thc hin nhit phng. Bt b

iu nhit tun hon, nhng khng lm nng nc (ci t nhit

300C).

Khi ng chng trnh Measure v chn Cobra 3 Chem - Unit. Ci

t s la chn nh sau: Get value every 300 ms trong X - data chn

Time bt u v kt thc chng trnh bng bn phm, v trong du

Channel chn Voltage (nh hnh 4). Chn hp Preferences chn

Voltage v chn ch in th hot ng ch o r3V v cng29

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chn Average over 1 valuve (nh hnh 5). Sau khi ng ca s ny chn

ch Displays. Ci t t -0,2 n 1V (nh hnh 6). Trong menu Digital

ci hin th Digital 1 l Voltage cc phn khc th off. Mn hnh hin th

ny ch ng vai tr iu khin.

Trong phn chn cho tt c cc hin th, trong khi

trong chn trong Diagram 1, chn

trong Diagram 1a v chn trong Diagram 1b v 1c. Ci t ch v chn (nh hnh 7). ng ca s ny. Kt thc ci t

bng .

Sau mn hnh hin th o c m. M rng s sao cho chim

khong 2/3 din tch mn hnh. hin th s din tch bn di ca mn

hnh. Cc gi tr o c kim sot ti y.

Bt cng tc iu khin vi pht trc khi bt u o (nh, ch bt khi

kh mang chy qua, trnh trng hp qu nhit u d). Gi nt Grob

v tr mt lt, sau iu chnh n gi tr ng nn 0V. Sau 3 pht,

kim tra li mn hnh hin th. Nu cc gi tr o thay i nhiu, th nhn nt

Grob 1 ln na. Nu vn cha t ta vn nt Fein t gi tr xp x 0

(V).

M van Heli v s dng dng c o bt x phng (vi bu cao su cha

1-2 ml dung dch x phng) iu chnh tc dng Heli 30 ml/ph

(10ml/20s). n vo bu cao su to v nh v bt x phng.

Hnh 4

30

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thc hin qu trnh tch sc k kh, trn n-butance v iso-butan

trong ng tim 1ml bng kim tim, ht 0,5 ml mi cht t erlen cha kh

chun b vo ng tim.

Bt u thu thp d liu t my tnh, sau cn thn a su u ng

tim vo septum v nhanh chng nhn ng pittong (nu c th hy thc

hin ng tc ny vi ln, m bo ton b mu c a vo). Rt

ng tim ra khi septum. Ch im bt u tch - thi gian tim - my tnh s bt u ghi li.

nhn bit cc peak ring l, chun b trn mt hn hp khc gm 2

kh, nh trong ln u nhng dng 0,2 ml iso-butane v 0,8 ml n-butane,

ln sau l 0,8 ml iso-butane v 0,2 ml n-butan. So snh kt qu ca sc

k kh vi mng sc ph ban u (pha trn 1:1).

Hn hp kh butan trong bnh kh c th tch ra theo cch tng t.

Thm vo hn hp kh trn l 2 ng phn n - butane v iso-butan, c

tim vo ct tch. Thay i np cao su (septum) sau mt vi ln tim, v

n s r r sau vi ln tim. Ngng lu thng kh li trc khi thay i

septum.

Hnh 5

31

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Hnh 6

Hnh 7

6.2. Tch hn hp etanol v etyl acetat

Dng 2 ng tim (1 ml) ly mi cht etanol v etylacetat 1ml cho vo l

nh c np. Hn hp ny c cha trong l nh c th bo qun c

mt thi gian ngn dng sau ny. Thc hin qu trnh tch kh 800C.

Ci t b iu chnh nhit n nhit ny v i cho n khi cp nhit

cm trong v ngoi bng thy tinh (glass jacket) n nh 800C. Qui

trnh tch sc k kh tip theo hon ton tng t nh m t trong phn 1.

Ht 5Pl hn hp, khng c bong bng, vo trong ng tim 10Pl. Bt u o,

cn thn a kim tim vo su xuyn qua septum, dng tay cn li p

32

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nhanh pittng. Ly ng tim ra khi ct nhanh chng (nhng cn thn, kim

rt d gy).

i vi qu trnh xc nh ester, tim mt hn hp u gm 4Pl hn

hp v 2Pl tyl acetat.

7. L thuyt:

Qu trnh tch sc k ca hn hp cc cht xy ra gia pha tnh l pha

m ct sc k c nhi y v pha ng l pha di chuyn vi tc

dng kh qua ct tch khng i. Trong sc k kh, pha ng l kh: n c

gi l kh mang. i vi qu trnh tch cc cht, cc hm c trng c th

c s dng (v d: hp th, phn b, trao i ion, gel thm thu). Sc k

kh thng c s dng nh l php ghi sc phn phi. Trong trng hp

ny pha tnh bao gm cht rn nn m trn b mt c mt lp cht lng

mng m pha tnh c xc nh chnh xc. Trong cc iu kin v ng

nhit, ng p quy lut phn b Nernst di y l c s cho vic thit lp

cn bng v phn b:

IIA

IA

aaK

K: h s phn b Nernst IAa : hot ca nguyn liu A pha 1

IIAa : hot ca nguyn liu A pha 2

Khi mt cht chuyn n ct tch, phn ln cn bng c thit lp

cho ph hp vi nguyn tc chn lc hay phn b Craig. Cht hot ng

mnh trong pha tnh th s di chuyn qua ct tch chm, ngc li cht ha

tan km trong pha tnh th di chuyn nhanh qua ct.

Tng t i vi s chng ct, kh nng tch ca mt ct c biu

din qua s mm l thuyt. S mm l thuyt cng ln th kh nng tch

cng tt hn. S a l thuyt N c th tnh l thng s ca chiu di ct

v chiu cao ca a mm l thuyt H:

HLN

Trong :

N: S mm l thuyt

33

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L: chiu di ct

H: chiu cao tng ng mi mm l thuyt.

Chiu cao mm l thuyt c tnh ton trc tip t sc k . Hnh 9

miu t c im v s lng ci m c th c t sc k . Cng

ca tn hiu l mt hm theo thi gian. Thi gian ng l thi gian m kh

khng c ct gi li cn i qua ct. T sc k chiu cao tng ng

ca mm l thuyt c th xc nh c. chnh l kh nng tch ca ct.

R 16tL bH 2

2

Hnh 8 Hnh 9

Thi gian lu th dng xc nh cc cht (nh tnh). Thi gian lu l

tnh cht c trng cho mt cht c th nhng iu kin nht nh.

Khu vc di mi peak ca mi cht cung cp thng tin nh tnh. Vi

nhng mi (peak) nhn, chiu cao mi c th dng tnh trc tip cho

vic nh lng.

I: Cng ca tn hiu

t0: thi gian bt u

tm: thi gian ng (thi gian cht)

tRA: thi gian lu ca cht A

tRB: thi gian lu ca cht B

ba: b rng mt y ca cht A

bb: b rng mt y ca cht B

8. L thuyt v kt qu

34

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Nhng kt qu s khc nhau vi nhng ct tch khc nhau. Vi nhng

iu kin c a ra nh trn th kt qu t c nh sau:

8.1 Qu trnh tch cc ng phn ca butane

Hai ng phn ca butane c th tch bi sc k kh, v c v trn

sc k (hnh 10 - 16). Khi t l gia cc ng phn l 1:1 th sc k ny

(hnh10) c so snh vi nhng sc k khc m trong hn hp kh

gm mt kh c thnh phn nhiu hn (hnh11 - 12), c th thy rng thay

i lin quan n chiu cao peak. S tng ln ca mi c cho l lin

quan n t l 1:1 vi cc ng phn c phn chia vt mc, v gim

ca mi cng l do lin quan n s phn chia (gim xung).

Hnh10 Hnh 12

Hnh 11 Hnh 13

35


C th xc nh c rng trong s tch ny iso-butane (mi 2) ra khi

ct tch trc n-butane (mi 3) (hnh 11 v 12). Mi 1 ca sc k kh c

to ra l do mt lng vt ca kh c tim vo vi mu.

Kt qu ca s tch hn hp kh t burner cartidge l sc k vi 5

mi (hnh 13). Mi u tin c th c quy l khng kh. S so snh sc k

t hnh 10 n 12 cho php kt lun mi 3 l iso-butane v mi 4 l n-

butane. Mi 2 l propane cng c mt trong hn hp kh t.

Tnh ng n ca s phn chia ny c th c gii thch bi s di

chuyn ca s tch sc k, mi loi hn hp kh t c ha trn vi mt

lng nh kh nguyn cht (hnh 14 - 16). Propane khng c dng

y nhng v nguyn tc c th tham gia vo qu trnh tch ri. Mt mi

sc k na c tm thy trong sc ph t hnh 13 ti 16 (mi 5). l kt

qu ca mt lng nh 1,3-butadien, iu ny ph hp vi nhn trn bnh

kh, n c cha trong hn hp kh.

Kt qu xc nh c trong thc nghim c th gii thch nh sau.

Cc ng phn ca butane khc nhau v nhi si. Isobutane l phn t

hnh cu c lc tng tc phn t yu v c im si ti -11,70C trong khi

n-butane l phn t thng v v vy n c n ra vi lc bm dnh ln

hn, kt qu l im si ca n cao hn -0,50C. V vy iso-butane s ra

khi ct trc n-butane.

S tch ca hn hp kh miu t di y di nhng iu kin nh

sau:

Nhit ct tch : 220C

Tc dng kh mang : 30 ml/pht,He

Tng lng kh bm vo : 1 ml kh/ hn hp kh

Thnh phn ca hn hp kh:

Hnh 10: 0,5 ml iso-butane + 0,5 ml n-butane



Hnh 13: 1,0 ml camping gas

Hnh 14: 0,6 ml camping gas + 0,4 ml n-butane

Hnh 15: 0,6 ml camping gas + 0,4 ml iso-butane

Hnh 16: 0,7 ml camping gas + 0,3 ml khng kh

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Hnh14

Hnh 15 Hnh 16

8.2 Qu trnh tch hn hp ethanol v ethylacetatS tch hn hp ethanol v ethylacetat (t l v th tch 1:1) cung cp

mt sc k vi hai mi (hnh17). Mi 1 trong sc k ny l ethanol v

mi 2 l ester. iu ny c th gii thch n gin bng ln tch th hai

dng 4Pl ca hn hp v ht 2Pl ca ester cho vo xy lanh microlite. Sc k

ca qu trnh tch ny miu t mt s khc bit kh ln, ph thuc vo

ln ca mi 2 vi mi 1 (hnh18), iu a n mt nhn xt rng

mi 2 chnh xc l ester. Php tch sc k ca hn hp ethanol v

ethylacetat c din ra di iu kin nh sau:

- Nhit ct tch : 800C

- Tc dng kh mang: 30ml/pht, He

37


Thnh phn ca hn hp phn tch:

- Hnh 17: 5Pl hn hp (ethanol/ester = 1/1)

- Hnh 18: 4Pl hn hp + 2Pl ester

Nu nh qu trnh tch sc k kh tch chnh xc theo nhit si th

cht c im si thp s c tch ra khi ct trc mt cht c im si

cao. C th thy iu trong v d ny, tuy nhin r rng l ethylacetat ra

khi ct mun hn ethanol d n c im si nh hn ethanol l 1,44K

(im si ca ethylacetat l 77,060C; ethanol l 78,50C).

V vy sc k kh cho php tch hn hp ra nhng thnh phn ring l,

nhng thnh phn ny khng th tch ri bi qu trnh chng ct, nh l

hn hp ng ph hay l hn hp nhng cht c im si tng t nhau.

c tnh ca s tch c th c ci thin tt hn bng vic thay i cc

ch .

9. Nhng iu cn ch

Vic s dng sc k tch cc cht c chng minh l mt

phng php tt trong phn tch. Phng php ny c th tch c mt

lng rt nh ca hn hp thnh cc thnh phn, v chng c th c

nhn bit bi nhng u d thch hp. Trong th nghim c miu t

y sc ph c th c tp hp d dng t nhng thnh phn ring bit,

v v vy n c nhng li ch ring, l cu trc v cng thc l nhng

yu t cn thit ca sc k th sinh vin c th hiu c. Ch pht hin

c thc hin bng cch s dng u d da vo mt in tr NST. N

nhn bit c mt lng nh kh da vo s khc nhau v dn nhit.

Tn hiu pht ra i qua b iu khin vi b khuych i n u vo ca

giao din Cobra 3, v sau v th v nh gi. Ct tch kh dng trong

sc k kh th c y vi dinonylphthalate, nh c hng dn

trn. Mc d ch c ct tch c s dng tch hn hp cc cht,

nhng vn s dng glass jacket, n gi cho nhit n nh thng qua

b iu nhit tun hon.

iu ny rt quan trng v v tr ca cc mi ca cc cht (thi gian

lu) ph thuc rt nhiu vo nhit , trong cc yu t th nhit thay

i tht thng lm cho ng nn khng c n nh. Heli c th c

http://hoahocsp.tk

dng lm kh mang (pha ng) trong php sc k ny. Tc dng kh c

th c iu chnh v quan st bng dng c o tc bt x phng.

Thnh phn ca kh t c th thay i tht thng. Trong c th

khng c propane, hoc c th ch c n-butane. Thnh phn ca kh trong

bnh cn phi kim tra trc khi dng kh thc nghim.

y chng ta khng tho lun v l thuyt ca phng php sc k.

Th nghim ny ch n thun l minh ha r nt cho nhng nguyn tc.

Nhng miu t chnh xc hn v bao qut hn s c tm thy trong cc

ti liu k thut.

Hnh 17 Hnh 18

39

http://hoahocsp.tk

BI 6: XC NH TC PHN NG V NNG LNG HOT HA CA PHN NG THY PHN

CH3COOC2H5 BNG HCl

1. Khi nim lin quan

Tc phn ng, hng s tc phn ng, phn ng bc 1, phn

ng bc 2, phng trnh Arrhenius, nng lng hot ho.

2. Nguyn l

Trong dung dch axit, CH3COOC2H5 thy phn thnh C2H5OH v

CH3COOH theo bc gi nh l 1. Lng axit to thnh c chun

bng phng php chun kim, t phng php ny c th rt ra kt

lun nng ca este ph thuc vo thi gian.

3. Nhim v

- Xc nh hng s tc phn ng cho phn ng thy phn

CH3COOC2H5 bng acid HCl 2 nhit khc nhau (hay nhiu hn).

- Tnh ton nng lng hot ha ca phn ng theo nhit t cc

hng s tc o c.



40


- ng xon gia nhit

- B iu khin ng xon gia nhit

- B iu nhit, 6l

- ng cao su d = 6mm


- u d nhit NiCr-Ni

- ng h bm giy

- Bp iu nhit c khuy t

- C t l = 15mm

- C t l = 30mm

- Thanh l = 500mm

- Thanh l = 750mm

- Buret, 50ml

- Kp gc phi

- Kp vn nng

- ng ong 100 ml

- Bnh nh mc, 1000ml

- Pipet 5ml

- Pipet 100ml

- Bp cao su

- a thy tinh, 1000ml

- Erlen, 250ml, c rng

- Erlen, 250ml, c cht

- Nt cao su 17/22mm

- Becher 250 ml

- Phu thy tinh

- Bnh tia 500ml

- CH3COOH, 250ml

- HCl 1M, 1000ml

- Dung dch NaOH 1M, 1000ml

- Dung dch phenolphtalein 1%

- Nc tinh khit 5l

08492.93

08492.01

08487.02

39282.00

07050.00

13615.03

03071.01

35720.93

46299.01

462.99.02

02022.05

37694.00

37720.00

37697.00

37715.00

36629.00

36552.00

36577.00

36582.00

39275.03

46245.00

36134.00

36424.00

39258.00

36013.00

34457.00

33931.00

30075.25

48454.70

48329.70

31714.10

31246.81

1

1

1

2

1

1

1

1

1

1

1

2

1

4

4

1

1

2

1

1

1

2

2

2

1

1

1

1

1

1

1

1

http://hoahocsp.tk

5. Lp t v vn hnh

Lp t dng c nh hnh v.

Chun b dung dch NaOH 0,2M bng cch ly 200 ml dung dch NaOH

1M cho vo bnh nh mc 1000ml, cho nc ti vch chun. Cho dung

dch NaOH 0,2M vo buret.

Dng pipet ly 100ml dung dch HCl 0,1M cho vo bnh erlen, y np

cho vo b n nh nhit khong 15 pht 350C (T1 ).

Cho 5ml dung dch CH3COOC2H5 vo bnh erlen cha HCl, lc vi ln

ri t vo b n nhit. C sau cc khong thi gian 10, 20, 30, 40, 50

pht, ly 5ml hn hp cho vo cc erlen c rng cha sn 100 ml nc ct

lnh (5 bnh), phn ng s dng ngay lp tc. Chun bng dung dch

NaOH 0,2M vi ch th phenolphtalin. Sau khi kt thc chui th nghim th

lp li qu trnh trn nhit 450C (T2).

Th tch ca NaOH ti thi im t0 ( : th tch cn trung ha

lng HCl lc ban u) c th c tnh theo l thuyt hoc da vo kt

qu th nghim. Xc nh chun ht 5ml HCl 0,1M.

NaOH,0V

NaOH,0V

Xc nh th tch NaOH thi v cng (phn ng chuyn h hon

ton) bng cch. em bnh nn cha hn hp cn li cho ln bp, un cch

thy (c khuy t) nhit khong 700C trong vng 30 pht. Lm ngui

hn hp ri chun bng dung dch NaOH 0,2M nh trn.

6. L thuyt

CH3COOC2H5 + H2O CH3COOH + C2H5 OH

Tc phn ng:

KWEE

R .C .Ck.C dtdC

v

Vi:

k: hng s tc phn ng.

CE, C W, CK: nng ca este, nc v xc tc ti thi im t.

V nng H2O v H3O+ l khng i, v vy ta c:

E 'E C k

dtdC

Ly tch phn 2 v, ta c:42

http://hoahocsp.tk

t kCC

ln 'E

E,0

Nng ca este CE,0 v CE ti thi im t0 v t c th thay bng th

tch dung dch NaOH cn cho qu trnh trung ha ca cc mu ti thi im

bt u NaOH;0V , trong qu trnh phn ng NaOHV v sau qu trnh chuynha hon ton f NaOH;V .

t klnQ VVVV

ln ,NaOH NaOH,

NaOH,0 NaOH,

f

f

Trong :

VNaOH, f : th tch NaOH dng chun thi im t =f VNaOH,0 : th tch NaOH dng chun thi im bt u

VNaOH : th tch NaOH dng chun thi im t.

Th tch VNaOH, 0 v VNaOH, f c th c xc nh bng th nghim

hoc c tnh bng cch s dng cc phng trnh sau:

105100

C.V CV

NaOH

1 HClNaOH,0 u

Trong :

V1: th tch mu (= 5ml)

CHCl: nng dung dch HCl (= 1M)

CNaOH: nng dung dch NaOH (= 0,2M)

NaOH,0 NaOHS E

1 EENaOH, V .C.V M

.V .VV f

Trong :

UE: khi lng ring ca este

ME: phn t lng este

VE: th tch dung dch este

VS: th tch ca dung dch (= 105ml) ti thi im t0.

43

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Hnh 2: th lnQ theo thi gian t, h s gc ng thng l k

Nng lng hot ha c xc nh theo phng trnh Arrhenius:

RTE

0'

A

.e kk

Trong :

R: Hng s kh (= 8,31441 J.mol-1.K-1)

kmax : Hng s trc ly tha

i vi 2 cp gi tr bit c hng s vn tc k1 v k2 tng ng vi

nhit T1 v T2.

0A' lnk

RTE

lnk

Ta c:

01

A' 1 lnk RT

E lnk

02

A'2 lnk RT

Elnk

Suy ra:

' 1

,2

12

2 1A k

klnT T

.T TR E u

44

http://hoahocsp.tk

BI 7: VN TC PHN NG TH HALOGEN

1. Khi nim lin quan

Tc phn ng, quy lut phn ng bc 1 v 2, dn in.

2. Nguyn tc

Cc nhm halogen alkyl phn ng trao i halogen nhanh trong dung

mi thch hp. Phn ng thay th ny xy ra theo c ch SN2. Vn tc ca

chng c th c xc nh mt cch thun li thng qua cc ln o dn

in.

3. Nhim v

- o dn in ca cc dung dch vi cc nng khc nhau ca

NaI trong acetone.

- Xc nh nng ca cc cht ng phn ng ca phn ng propyl

bromua vi NaI trong aceton 300C.

- Xc nh hng s tc phn ng.



45


- Thit b o dn - u d nhit v dn- Bp khuy t- Dng c ci t nhit - C t, l = 25mm - C t, l = 50mm - ng h bm giy - Da cn - Thanh , l = 750mm - Kp gc phi- Kp vn nng- Da thy tinh, 1000ml - Bnh cu 3 c- ng sinh hn - ng thy tinh thng, l = 80mm - Septum - Cn - ng ong 100ml - Xylanh 1ml - Kim tim, 0.6 x 60 mm - Pipet - Bp cao su - Phu- Beaker 50 ml - Mung - ng cao su, d = 6mm - Kp ng, d = 812mm - n - propyl bromide 250ml - NaI 50g - Aceton 250ml

13701.93 13701.01 35720.93 35721.00 46300.01 46299.03 03071.01 03065.20 02023.20 37697.00 37715.00 46245.00 35677.15 35815.15 36701.65 02615.03 48852.93 36629.00 02593.03 02599.04 36590.00 39275.03 34472.00 36001.00 33398.00 39282.00 40996.01 31756.25 31634.05 30004.25

1 1 1 1 1 1 1 1 1 3 2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 4 1 1 1

5. Lp t v vn hnh

Th nghim c lp t nh hnh 1. Rt 100ml aceton vo bnh cu

y trn c nhng chm vo b cha nc. t c t thch hp bnh

cu y trn v b cha nc, bt u khuy. t in cc o dn in

http://hoahocsp.tk

vo 1 ci c ca bnh cu, ni in cc vi thit b o dn, la chn

chc nng o dn in ring. Ci t b cm bin in t ca my

khuy t 350C v bt ngun gia nhit. Khi t n nhit ci t,

o dn in ca dung mi nguyn cht m gi tr c th l vi mS/cm.

Thm chnh xc 6,805g (4,54.10-2 mol) NaI, chia lm 7 phn, mi phn

0,97g cho vo ci c cn trng ca bnh cu. Sau mi phn cho vo ch

mui phn hy hon ton v nhit c thit lp (khng thay i),

trc khi o dn in. Ghi li khi lng NaI sau mi ln thm vo v o

dn in ri v ng cong dn in theo nng NaI.

Khi ton b khi lng NaI c thm vo, bt u thc hin php o.

C th ba ca bnh cu c gn ng thy tinh ngn v y cht bng nt

cao su. Tim 4,2ml propyl bromua (4,54.10-2 mol 300C) xuyn qua ci nt

cao su v ngay lp tc o dn ca dung dch (ti thi im t0). Tip tc

o dn trong khong thi gian 5 pht mt ln. Kt thc qu trnh o sau

90 pht.

6. L thuyt

Phn ng Finkelstein tin hnh theo c ch phn ng SN2

C3H7Br + I- = C3H7I + Br-

Vn tc ca phn ng ny l 1 hm s ph thuc vo nng ca 2

cht phn ng v n tun theo quy lut phn ng bc 2.

IPrBrPrBr C kC

dtdC (1)

Trong : k l hng s tc phn ng

CPrBr, CI- l nng propyl bromide v ion I- ti thi

gian t

V nng u ca C3H7Br v NaI bng nhau (CPrBr,0 = CNaI,0), nn

phng trnh c th c vit nh sau:

2PrBr

2I

PrBr kC kCdt

dC (2)

Sau khi ly tch phn 2 v ca phng (2) ta c:

PrBr,0PrBr C1kt

C1 (3)

47

http://hoahocsp.tk

Hnh 2: S ph thuc ca dn in N vo nng ca NaI

Nng ca NaI cn li trong qu trnh phn ng ti thi im (t)

c xc nh bng ng cong chun (hnh 2). T xc nh nng

propyl bromide (CPrBr) theo phng trnh sau:

CPrBr = CI- = CNaI (4)

Ri th v th nng propyl bromide theo thi gian CPrBr - t

Hnh 3: th nng theo thi gian (CPrBr = CI- = CNaI) ca phn ng gia

propyl bromide vi I-

xc nh bc phn ng, v th PrBrC1 - t

48

http://hoahocsp.tk

Hnh 4: Xc nh bc phn ng v hng s tc ca phn ng propyl

bromide vi I-

Mi quan h tuyn tnh giaPrBrC1 v t c minh ha hnh 4 ti

y c s hin din ca phn ng bc 2. Vi h s gc ca ng thng l

hng s tc k = 1,5.10-3 l.mol-1.s-1 (v gi tr k = 1,37.10-3l.mol-1.s-1

2980K)

Vn tc ca phn ng Finkelstein ph thuc vo c tnh ca dung mi

ban u. V l do ny, nhng chch lch ca cc gi tr o xy ra ty theo

tinh khit ca aceton c s dng.

49

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BI 8: DN IN TRONG CHT RN

1. Khi nim lin quan

S dn in ca electron v ca ion.

2. Nguyn tc

Xc nh in tr ca cht rn ph thuc vo nhit , n cho bit c

ch v s dn in v thay i in tch trong cht rn.

3. Nhim v

Xc nh h s nhit in tr i vi dy st, ng v dy

Constantan trong gii hn t nhit phng n 950C.



50

http://hoahocsp.tk

Hnh 2: S lp mch in

Nt mutrng

Nt mu vng

sensordy mu

dy mu

dy mu xanh

- Cobra3 Unit

- Ngun cung cp 12V/ 2A

- Cp truyn d liu, RS232

- Phn mm Cobra3 Universal writer


- u d nhit NiCr-Ni

- Ngun cung cp vn nng

- Bp khuy t

- C t, l = 30mm

- Thanh , l = 500mm

- Thanh , l = 250mm

- Kp gc phi

- Kp vn nng

- Pin cch in

- Dy ni, l = 500mm, mu

- Dy ni, l = 750mm, mu

- Dy ni, l = 750mm, mu xanh

- Becher 1000ml

12150.00

12151.99

14602.00

14504.61

07050.00

13615.05

13500.93

35720.93

46299.02

02022.20

02031.00

37697.00

37715.00

07807.00

07361.01

07362.01

07362.04

36017.00

1

1

1

1

1

1

1

1

1

1

1

4

1

2

2

1

1

1

51

http://hoahocsp.tk

- Ko

- Dy ng

- Dy st

- Dy constantan

- Nc ct

64798.00

06106.00

06104.00

06100.00

31246.81

1

1

1

1

1

5. Lp t v vn hnh

Lp t thit b th nghim nh hnh 1 v hnh 2.

Chun b 3 mu dy kim loi. Tip theo ct mu dy th nht di 30cm

v qun mu dy vng quanh cy bt ch, lp li qu trnh trn cho 2

mu cn li. Phi m bo tng vng xon ring l khng c chm vo

nhau. Ni mu th nht vo hai kim o cch in v nhng chm n vo

trong beaker c cha sn c t v nc ct. Phi chc chn rng mu

hon ton ngp trong nc.

Ni u d S2 v hai kim cch in vo hai l nh bn di Analog ln

1 ca thit b cobra3 basic unit.

Khi ng chng trnh Measure trong windows v chn . Ci t cc thng s o nh trong hnh 3.

Hnh 3

Di diagram 1 chn t 0 - 5 Ohm, gii hn X:

0 - 15 v . Sau khi thc hin nhng bc trn nhn

chp nhn cc gi tr c ci t. Sp xp cc hin th

nh bn mong mun.52

http://hoahocsp.tk

ghi li cc ln o ring bit, ci t in th ca dy ng xp x

0,25V v 1,2V cho dy st v Constantan. Chn tc khuy ca c t va

phi. Ghi li im o u tin ti nhit phng bng cch nhp vo . o 20 ln ti nhit ny ly gi tr Rc trung bnh. Sau ta tng

nhit mi trng bng cch un nng nc di s khuy lin tc. Ghi

gi tr o sau mi ln tng 50C. Ta ngng o khi nhit t n 950C v

ghi li d liu vi ng dn < Save the measurement as >.

th biu din s ph thuc vo nhit ca in tr c th c

chun b bng cch nhp vo trong menu

. Ci t cc thng s nh hnh 4.

Hnh 4

Hnh 5 - 7 cho thy in tr ca 3 thanh kim loi ph thuc vo nhit

. Di ta c th chn v thay vo s

xut hin ng thng hi quy.

6. L thuyt

53

dn in trong cht rn ph thuc vo kiu lin kt cc thnh phn

ca cht rn, m ch yu l lin kt kim loi v lin kt ion. Do chng ta

phi quan tm n dn electron v dn ion.

dn in c quan st trong cc kim loi, hp kim v nhng

nguyn liu khc c nh kim nh: graphite, mt vi oxit kim loi, sulfit kim

loi Hu ht cc cht bn dn c s dng trong cng ngh in v

http://hoahocsp.tk

in t v cc cht c lp cng l cc cht dn in. Tnh dn in ny th

lin quan n lin kt kim loi. Trong vn ny, cc electron ngoi cng

ca li kim loi th c lin kt yu v c th chuyn ng gia cc ht

nhn nguyn t. Tuy nhin cc electron lin kt khng thuc v nguyn t

ring bit no, nhng thuc v tt c, lin kt ca chng th khng c nh

hng khng gian. Nhng ion linh ng trong li kim loi gy ra s dn

in. Thuyt lin kt v s di chuyn ca cc electron trong cht rn gii

thch hin tng da trn cc trng thi nng lng khc nhau ca cc

electron trong cht rn.

Di o dn in c trn 30 bc, t cc cht c lp c dn in

bng 1022 1 : .cm-1 n 10-8 1 : .cm-1 ca cc kim loi tinh khit.

dn ion l kh nng dn in ca mt cht bi dng chuyn di

ca cc ion. Tt c cc dung dch in phn, mui nng chy v nhng

mui rn l cc hp cht ion in hnh u l cc cht dn in ion. Do lin

kt bn trong mng li tinh th ion ca cc mui rn, linh ng ca cc

ion, do dn in rt nh nhit phng. Bng s gia tng nhit

th cc lin kt dn dn yu i, v cc ion tr nn cng ngy cng linh ng

hn. Hin tng ny tip tc tng ln ti im nng chy v hn na. S

gia tng ca nhit s lm gim in tr sut. iu ny th tri ngc s

ph thuc ca dn in vo nhit . Vi cc kim loi th s gia tng ca

nhit s khng lm tng s lng hoc linh ng ca cc electron.

linh ng gim cng nh vic tng nng lng nhit ca cc ion kim loi

s lm tng cc dao ng nhit xung quanh v tr ca n trong mng li

tinh th. Kt qu l, c s tng ln tng ng v s va chm ca electron

v cc ion kim loi, lm gim chiu di qu o chuyn ng ca cc

electron. iu ny s lm gim dn in.

T cc gi tr thc nghim ca dng in v hiu in th, in tr R

c th c tnh ton theo cng thc:

IUR (1)

Trong :

U: hiu in th (V)

I: Cng dng in (A)

54

http://hoahocsp.tk

Hnh 5: S ph thuc ca in tr vo nhit trong dy st

H s dn nhit theo nhit c nh ngha nh l dc ca

ng cong ca in tr sut theo nhit .

12TTT

T TRR R

1

12

(2)

Hnh 6: S ph thuc ca in tr vo nhit trong dy ng

Hnh 7: S ph thuc ca in tr vo nhit trong dy Constantan

55

http://hoahocsp.tk

iu ny ch ng nu ng cong biu din in tr sut so vi nhit

l mt ng thng, m ng thng th khng vt qua gii hn

ln nht ca nhit .

Sau y l cng thc ph hp hn ca s khc nhau v thng s c

th c dng. Cng thc sau y ch ra rng s ph thuc ca in tr

mi cht ph thuc vo nhit :

dTdR

R1 u (3)

Nhit tr sut c th tnh ton t gi tr thc nghim:

TR

R1

C

u (4)

Trong :

RC : in tr nhit phng

TR : dc ca ng thng

D : H s nhit ca in tr

Da vo phng trnh (4) chng ta c, DFe = 4,6.10-3 K-1 v DCu = 4.10-3

K-1.

56

http://hoahocsp.tk

BI 9: PHNG TRNH NERST

1. Khi nim lin quan

S ph thuc ca th in cc vo nng ca dung dch in cc,

in cc oxi ha kh, pin in ha.

2. Nguyn tc

Phng trnh Nernst pht biu th in cc ca pin ph thuc vo

dung dch v nng (hot ) ca ion . Phng trnh ny c minh

ha bng thc nghim khi s dng pin in ha c to thnh t in cc

ch th kt hp vi in cc so snh.

3. Nhim v

- o in th ca in cc platium trong dung dch cha nng

bit ca Fe(II) v Fe(III) v hn hp ion [Fe(CN)6]4- v

[Fe(CN)6]3-.

- Tnh th in cc ca in cc so snh nhit th nghim

- Tnh th in cc chun ca ti nhit th nghim.0 Fe ,Fe 23E



57


- pH - meter - in cc so snh Ag/AgCl/Cl-

- ng bo v in cc platin

- Dy ni, l = 500mm, en

- in cc Pt

- My khuy t

- C t

- Chn , h = 750mm

- Kp gc phi

- Kp vn nng

- Thanh 2 in cc

- Kp gi buret

- Buret 50ml

- Cn phn tch

- Da cn

- Becher 100ml

- Becher 150ml

- Bnh nh mc 1000ml

- Pipette 50ml

- Phu thy tinh, d = 55mm

- Phu thy tinh, d = 80mm

- Mung

- Bp cao su

- Bnh tia

- K4 [Fe(CN)6]: 250g

- K3 [Fe(CN)4]: 100g

- Nc ct

13702.93

18475.00

45206.00

07361.05

13702.01

47334.93

46299.02

37694.00

37697.00

37715.00

45284.01

03065.20

36517.01

48802.93

45019.05

36002.00

36003.00

36552.00

36581.00

34457.00

34459.00

33398.00

39275.03

33931.00

30101.25

30100.10

31246.81

1

1

1

1

1

1

1

2

2

1

1

2

2

1

1

2

4

4

2

2

2

1

1

1

1

1

1

5. Lp t v vn hnh

Lp t th nghim nh hnh 1.

Chun b dung dch cho th nghim nh sau:

http://hoahocsp.tk

- Pha dung dch K4[Fe(CN)6] 0,01M: cn chnh xc 4,2239g mui

K4[Fe(CN)6].3H2O. Cho K4[Fe(CN)6].3H2O vo bnh nh mc 1lit.

Ha tan bng nc ct, sau nh mc n vch chun.

- Pha dung dch K4[Fe(CN)6] 0,001M: dng pipet ly 100ml dung

dch K4[Fe(CN)6] 0,01M cho vo bnh nh mc 1l, sau nh

mc n vch chun bng nc ct.

- Pha dung dch K3[Fe(CN)6] 0,01M: cn 3,2925g K3[Fe(CN)6] cho

vo bnh nh mc 1l, ha tan bng nc ct, sau nh mc

n vch chun.

- Pha dung dch K3[Fe(CN)6] 0,001M: dng pipet ly 100ml dung

dch K3[Fe(CN)6] 0,01M cho vo bnh nh mc 1l, sau nh

mc n vch chun bng nc ct.

S dng 2 ci burette, mt dng cho dung dch Fe(II) 0,001M v mt

dng cho dung dch Fe(III) 0,001M, t vo chn gi , trng 2 ln bng

dung dch tng ng nh trn v cho dung dch tng ng vo n vch

mc. Chun b dung dch mu theo bng 1.

t becher cha dung dch mu u tin vo my khuy t v cho c

t vo becher. Sau , ni in cc Platin, in cc so snh v u d

nhit vo my o pH v nhng chng ngp trong dung dch. Ghi nhit

v sc in ng ca pin. Ra sch in cc bng nc ct, lm kh v

t chng vo trong dung dch mu k tip, qu trnh ny phi c lm

nhanh. Khng nn in cc so snh ngoi dung dch qu lu. Tip tc

o cho n ht cc mu. Lp li quy trnh trn vi dung dch 0,01M. Tnh

sc in ng ca pin nh l mt hm s:

> @ > @

4 6

3 6

CN FeCN Fe

ln

Bng 1: Chun b cc dung dch mu

Dung dch Fe (II)(ml)

Dung dch Fe (III)( ml)


Dung dch Fe (III) ( ml)

49 1 20 30

48 2 12 38

46 4 7 43

59



Dung dch Fe (III)( ml)


Dung dch Fe (III) ( ml)

43 7 4 46

38 12 2 48

30 20 1 49

25 25

6. L thuyt

Pin in ha c s dng y, in cc Ag /AgCl/ Cl- c dng

lm in cc so snh cung cp mt in th c nh xc nh th ca

in cc oxy ha kh.

in cc bc clorua gm c mt si dy Ag c bao ph bi AgCl v

c nhng trong dung dch KCl c nng xc nh.

in cc oxi ho - kh l cp Fe(III)/ Fe(II):

[Fe(CN)6]3- + e- = [Fe(CN)6]4-

Thng thng, mt phn ng oxi ho - kh m ion Xz+ nhn n electron

thnh ion Y c in tch (z - n)+ c th c th hin nh sau:

Xz+(dd) + ne- =n) (zY

Trong h thng ny, trng thi cn bng t c khi tng ha th ca

mi v phn ng cn bng nhau:

Px(dd) + n.Pe (kl) = PY(dd) (1)

T nh ngha v ha th, ta c phng trnh sau:

Px(dd) = Px + zFMdd (2a)

Pe(kl) = Pe + FMdd (2b)

PY(dd) = PY + (z-n)FMdd (2c)

Vi:

Mdd: in th ca dung dch

M(kl): in th ca in cc kim loi tr

P i: ha th ca cu t i

Kt hp phng trnh (1) v (2), ta c:

klddeYX nFnFn n) (zz (3)

http://hoahocsp.tk

S chch lch in th 'M gia dung dch v kim loi c biu din:

n ) ( nF1

eYxkl dd n) -(zZ M MM (4)

in th ion ph thuc vo hot ca ion trong dung dch:

(5a) Zzz X0XX

RT.lna

(5b) n) (Zn) -(zn) -(z Y0YY

RT.lna

Phng trnh (4) c th c vit di dng

n) (z

z

n) (zz

Y

Xe

0Y

0X a

a ln

nFRT n

nF1 (6)

Phng trnh Nernst cho in cc oxi ha kh:

n) (z

z

2323

Y

X0Fe ,FeFe ,Fe a

a ln

nFRTEE (7)

Pin c s dng trong th nghim ny l:

(-) Ag/ AgCl/ KCl (3M)/ Fe3+, Fe2+/ Pt (+)

Th in cc ca in cc dng:

> @> @

23

0Fe ,FeFe ,Fe Fe

Fe lnnFRTEE 2323

Th in cc ca in cc m:

> @-0Ag/AgCl/Cl Ag/AgCl/Cl Cl lnnFRTEE

M 25 tdtdEEE 025

0 t

Sut in ng ca pin (Epin) l:

Ag/AgCl/Cl Fe, Fepin EE E 23

> @> @ Ag/AgCl/Cl 2

30

Fe ,Fe pin E

FeFe ln

nFRTEE 23

(8)

i vi dung dch long s dng y, hot c thay th bng

nng mol.

Sc in ng Epin ph thuc vo ln([FeIII]/[FeII]) theo phng trnh

ng thng dng (y = ax + b) c h s gc RT/F v tung gc

(hnh 2). Nu bit c th ca in cc so snh s dngAg/AgCl/Cl0 Fe ,Fe EE 23

61

http://hoahocsp.tk

th th ca in cc chun ca cp oxi ha kh FeIII,FeII c th xc nh

c.

H s gc ca ng thng (xc nh bi ng hi quy n gin) l

25,2 mV (gi tr RT/F = 25,4mV ti 22oC)

T gi tr ca Epin ti giao im trc Y ta c = 172

mV. Ti 20

Ag/AgCl/Cl0

Fe ,Fe EE 23

0C Ag/ AgCl/ Cl in cc so snh c th 210 mV. T , th oxi

ha kh ca in cc chun E0[Fe(CN)6]3-,[Fe(CN)6]4- l 38mV (ti liu:

36mV theo R. Parsons, s tay in ha, Butterworth, London, 1959).

62


BI 1: XC NH ENTAPY CA QU TRNH HA HI CHT LNG

Ngy thc hnh :

H v tn sinh vin :

im Li ph

- Khi lng mol ca CH3OH: 32,04 g.mol-1

- Khi lng mol ca C2H5OC2H5: 74,12 g.mol-1

- Nhit si ca CH3OH: 337,7 K

- Nhit si ca C2H5OC2H5: 307,7 K

1. Kt qu o:

Cht bay hi Khi lng cht bay hi (m) Nhit lng

Wel (J)'TV 'Tel

Dietyl eter

Metanol

2. Xc nh nhit ha hi C2H5OC2H5 ----------------------------------------------------------------------------------------------------

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3. Xc nh nhit ha hi CH3OH.

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4. Tnh ton 'S ca qu trnh ha hi v ng dng quy lut Trouton

phn tch kt qu.

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5. Hy trnh by nguyn tc ca th nghim

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6. Ti sao nhit si ca cc cht trong th nghim trn li thay i

trong sut qu trnh bay hi?

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7. Ti sao cc lin kt ha hc nh lin kt hydro lm tng entapy ca

qu trnh bay hi cht lng?

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8. Hy gii thch ti sao khi m bm chn khng th cht lng mi bt

u bay hi?

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9. Gii thch ti sao khi m van kh qu ln s lm tr hon qu trnh si?

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10. Hy cho bit cc yu t nh hng n sai s ca kt qu th nghim.

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http://hoahocsp.tk

BI 2: TNG IM SI

Ngy thc hnh :

H v tn sinh vin :

im Li ph

1. Kt qu o:

- m1 :

- m2 :

- Khi lng ca nc (dung mi nguyn cht):

Mu Khi lng cht tan (mg) dmct

mm

STS

S

KT

1

2

3

4

5

67

2. V th

dm

ct

S

S

mm

KT


3. Ti sao phi nn cc vin cht tan?

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4. Ti sao khng un si trc tip dung dch cha cht tan trn bp in

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5. Ti sao phi kha van pinchcock sau khi qu trnh si tr li?

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6. Ti sao khi cho cht tan vo th nhit si li gim sau mt thi gian

mi tng tr li?

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7. Ti sao nhit si ca dung dch cao hn nhit si ca dung mi

nguyn cht?

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8. Hy cho bit nhit si thc t ca dung mi trong th nghim ny v

gii thch ti sao?

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9. Xc nh phn t lng ca cc cht tan: mui, ur v hydroquinone.

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BI 3: XC NH NHIT TO THNH CA NC

Ngy thc hnh :

H v tn sinh vin :

im Li ph

1. Tnh nhit to thnh ('H) ca nc. So snh kt qu vi s tay ha l.

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2. Ti sao phi dng d oxy?

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3. Khi no th entapy ca phn ng c gi l nhit to thnh ca phn

ng.

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4. Ti sao phi y ng thi 2 xylanh kh?

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5. Nu a ln lt tng kh bo bnh phn ng ri mi bt tia la in

th hin tng g s xy ra?

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6. Ti sao in cc phi t ngay u vo ca ng dn kh hydro?

Nu ta t in cc ti ng dn kh oxy th hin tng g s xy ra?

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7. Trnh by phng php kim tra s r r kh trong h thng?

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8. Ti sao ta phi di chuyn thanh nam chm qua li nhiu ln?

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http://hoahocsp.tk

BI 4: CN BNG LNG - HI

Ngy thc hnh :

H v tn sinh vin :

im Li ph

1. Kt qu th nghim:

Stt p sut P (hPa)Nhit T

(0K) lnP T1

74


Stt p sut P (hPa)Nhit T

(0K) lnP T1

2. V th:

T1 flnP

3. T h s gc ( R HV ) ca ng thng hnh 2, xc nh H ca

qu trnh bay hi aceton.

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4. Ti sao phi cho 3 git aceton vo bnh bo v bc ngoi?

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5. Ti sao sau khi aceton si mi t bnh cu 3 c ngp trong dung dch

sinh hn?

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6. Ti sao phi kha van 1 chiu sau khi h bnh cu ngm vo hn hp

sinh hn?

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7. Entapy ca qu trnh bay hi ph thuc vo cc yu t no?

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8. Trong lc tin hnh th nghim i khi nhit trong bnh cu khng

i nhng p sut hi o c li tng. Hy gii thch hin tng v

a ra phng n khc phc

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Giáo Trình Hóa Lý Nâng Cao

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