Ind i an Journ al of Pure & Appli ed Ph ysics Yol.3 7. August 1999. pp. 59 1 - 594 Ultrasonic velocities and isentropic compressibilities of N,N-dimethylformamide + cyclopentanone + I-alkanols at 303.15 K P Venkate su & M V Prabh ak ara Rao· Depa rt ment of Chem istry. Sri Yenkateswara Univers it y. Tirupati 517 502 Rece ivc d I June 1998: rev ised 10 Se pt ember 1998: accepted 18 Janu ary 1999 The ultraso ni c ve loci t ies in te rn ary mi xtures of N.N- dim et hylfo rm am i de + cyc lope nt anone + I-propano l. I-butanol. 1- pe ntanol and I-hexanol have been measured at 303.15 K. Isentropic compressibilitie s. Ks' were calculated from ultr aso ni c ve loc i ty and dens it y data. Excess ise ntrop ic com press ib ilities. K .:'. we re al so comput ed . Negat ive values of K:' we re obtaincd fo r a ll the systems throughout the range of volume fraction s. The res ult s are interpreted on the bas is of mo lec ula r inte raction s be tween unlik e mo lec ul es. 1 Introduction In recent years th e measureme nt of ultraso ni c veloc- ity ha s been adequately employed in understanding th e nature of molecular in te rac ti ons in pure liquids a nd li qui d mi xtu res. These stu dies are of importance because of th e ir extensive use in textiIe industry, lea th er indus- tr y, ph armaceutical i nd ustry and in many oth ers. The ultraso ni c studies for th e binary mi xtures of N, N- dimeth ylfo r ma mide with substi tu ted benzenes 1 , wi th ketones 2 , with alcohols 3 ,4 with branched a lc ohols5, with aliphati c esters 6 , with tetrahyd rofuran 7 , w ith c hl o- roethanes and chl oroethenes 8 and w ith v in y lpy rr olidine 9 are a lready repo rt ed in th e li teratur e. An exhausti ve survey of literature has shown that a few attempts have been made for th e isentro pi c compressibility data of . 10-17 H fe h te rn ary mi xtu res . owever, no e lort appears to ave been made to co ll ect th e isentro pi c compressibility data fo r th e tern ary mi xtures of N,N-dimethy lf ormamide, cyclopentanone w ith I- a lk anols. Hence, these experi- mental data are re po rt ed fo r isentro pi c compressibility of N, N- di me th ylforma mi de + cyclopentanone -+- 1- propanol, -+- I-b ut ano l, -+- I-pen tano l and -+- 1- hexanol at 303. 15 K. The ma in purpose of this pa per is to charac- te ri ze th e molec ul ar interact io ns in these systems and to s ub sequ e ntl y eva lu ate the effect of cha in length of I-a l- cohols on th e ultraso ni c velocity va lues of th ese mi x- tures. 2 Experimental Details Analytical grade N,N-d im ethylfo rm amide was puri- fie d as described by Corrad ini et 01. 18 Cyclopentanone was purified by the method described by Ve nk ateswa rl u a nd Raman 1 9. The I-al kanols were further purified by the meth od described by Rao a nd Na idu 20 The purity of each sa mple was confirmed by GLC where si ngle sha rp pea ks. The measured density a nd ul traso ni c veloc i ty data of these compounds and th ose re ported in the lit erature are li sted in Ta bl e I and are in ag ree ment. Isentropic compress ibilities were computed from th e measured ul traso ni c veloc iti es and dens iti es, eva luated fro m th e meas ur ed excess volumes. Ultraso ni c ve loc i- ti es were measured by a si ngle-crystal ultraso ni c inte r- ferometer (Mittal Company, New De lhi , Model o. M 8 1) at 4 MHz frequency at 303 . 15 K. These were acc u- rate to ± 0.02%. Dens iti es of th e Iiquids were determ i ned with a bi cap ill ary type pycnometer, of ca pac i ty 12 cm 3 , Tab le I. - Ultrasonic ve loc ity (U) and den sity (p) of pure co mpo- nen ts at 303 . 15 K Compone nl N.N-di- JIlc thy I for- mamick Cyclopen- tano nc l-propanol 1-butanol I-pcn tanol I-h exanol pig cm- 3 Exptl Lit 3.t9 . 21 Ex ptl 1462 1371 11 89 1226 12 58 1284 1462 1373 11 91 1224 1256 1287 0.94 1 18 0.939 01 0.796 0 1 0.802 03 0.807 61 0.8 12 03 Lit 3. 19.2 1 0.94 1 20 0.939 02 0.796 00 0.802 06 0.807 64 0.812 0 1
Transcript
Indian Journal of Pure & Applied Physics Yol.37. August 1999. pp. 59 1 - 594
Ultrasonic velocities and isentropic compressibilities of N,N-dimethylformamide + cyclopentanone + I-alkanols at 303.15 K
P Venkatesu & M V Prabhakara Rao·
Department of Chemistry. Sri Yenkateswara University. Tirupati 517 502
Rece ivcd I June 1998: rev ised 10 September 1998: accepted 18 January 1999
The ultrasonic ve loci ties in ternary mixtures of N.N- dimethyl form am ide + cyc lopentanone + I-propanol. I-butanol. 1-pentanol and I-hexanol have been measured at 303 .15 K. Isentropic compressibilities. Ks' were calculated from ultrasonic
ve locity and density data. Excess isentropic compress ib ilities. K .:'. were also computed. Negative values of K:' were obtaincd
fo r all the systems throughout the range of volume fractions. The results are interpreted on the bas is of mo lecular inte ractions between unlike molecul es.
1 Introduction In recent years the measurement of ultrasonic veloc
ity has been adequate ly employed in understanding the nature of molecular in teractions in pure liquids and liquid mixtures. These studies are of importance because of their extensive use in text i Ie industry, leather industry, pharmaceutica l ind ustry and in many others. The ultrasonic studies for the binary mi xtures of N, Ndimethylformamide with substi tuted benzenes 1 , wi th ketones2
, with alcohols3,4 with branched alcohols5, with
aliphati c esters6, with tetrahydrofuran7
, with chl oroethanes and chloroethenes8 and with vinylpyrrolidine9
are already reported in the li terature. An exhaustive survey of literature has shown that a few attempts have been made for the isentropi c compress ibility data of
. 10-17 H fe h ternary mi xtures . owever, no e lort appears to ave been made to collect the isentropic compressibili ty data fo r the ternary mixtures of N,N-dimethylformamide, cyclopentanone with I-a lkanols. Hence, these experimental data are reported fo r isentropi c compress ibility of N, N-di methylformami de + cyclopentanone -+- 1-propanol, -+- I-butano l, -+- I-pen tano l and -+- 1- hexanol at 303. 15 K. The main purpose of this paper is to characterize the molecular interactions in these systems and to subsequently evaluate the effect of chain length of I-alcohols on the ultrasonic velocity va lues of these mixtures.
2 Experimental Details Analytical grade N,N-d imethylfo rmamide was puri
fied as described by Corrad ini et 01. 18 Cyclopentanone was purified by the method described by Venkateswarl u
and Raman 19. The I-alkanols were further purified by the method described by Rao and Naidu20 The purity of each sample was confirmed by GLC where single sharp peaks. The measured density and ultrasonic veloc ity data of these compounds and those reported in the literature are listed in Table I and are in agreement.
Isentropic compress ibilities were computed from the measured ul trasonic veloc iti es and densities, eva luated from the measured excess vo lumes. Ultrasonic veloc ities were measured by a si ngle-crystal ultrasonic interferometer (Mittal Company, New Delhi , Model o. M 8 1) at 4 MHz frequency at 303 .15 K. These were acc urate to ± 0.02%. Densiti es of the I iquids were determ ined with a bicap illary type pycnometer, of capac ity 12 cm3
,
Tab le I. - Ultrasonic ve loc ity (U) and density (p) of pure components at 303 .15 K
Componenl
N.N-diJIlcthy I formamick
Cyclopentanonc
l-propanol
1-butanol
I-pcn tanol
I-hexanol
pig cm-3
Exptl Lit3.t9.21 Exptl
1462
1371
11 89
1226
1258
1284
1462
1373
11 9 1
1224
1256
1287
0.94 1 18
0.939 01
0.796 0 1
0.802 03
0.807 61
0.8 12 03
Lit3. 19.2 1
0.94 1 20
0.939 02
0.796 00
0.802 06
0.807 64
0.812 0 1
592 INDIAN J PURE APPL PHYS. VOL 37, AUGUST 1999
which offers an accuracy of 2 parts in 105. The tempera
tu re was maintained us ing electronica ll y contro lled
thermostat havi ng an accuracy of ± 0.0 I K .
3 Results and Discussion The isentropic compressibility (KsJ23 ) of ternary mix
tures was calculated from the expression: v [) -2 - I "' 5123 = 123 P l21 .. . ( I )
\-"here U 12.1 , P 123 denotes ultrason ic ve locity and density of ternary mi xture , respective ly.
Excess isentropic com press ibility K::;n was esti
mated using the relation:
K :'m- Ksl23 - ~IKs l - ~2Js2 - ~JKs.l .. . (2)
where ~I, ~2 , ~ 1, and Ksi. Ks2 , Ks.1 are vo lum e fractions an d isentropic compress ibilities of the three pure com-
pounds. The quant ity dK ~2.1 the di fference between the , E
measllred va lue o t K "23 and that of computed from
F' binary data f( .i13 have been ca lculated using the rela-
tion: dK 1 = K I: - K I ' (3 .1~1 .121 .• 12.1 ... )
The latter quant ity was computed using the relation:
K F' = K I: + K I :" + K I:" , I 2.1 • I 2 " 3 ,~.l
... (4)
'1 ab le 2 - Volu mc fraction ( ~ I ) of N. N-<limcthy lform amidc. d~n,ity (r») . ultrasonic v.: loci ty (lJ ). isent ropi c compressibi li ly (Ks).
cxcess isentrop ic comp rcs~ ib il i[y ( /\ ::" ) fo r ~'N- di rm:thylfo r-
mCll11 ide ( I ) + c\ c lopenlano lH: (2) a t 03 . 15 K
~I pi g cm -3 1m s -I " 'sr rPa -I ".1 r rp -I , a
0.1134 0 .93903 1385 555 -4
0 191 1 0.93991 1393 549 -S
0.266 1 0.938 8 1 1402 542 -6
0.3373 0.93975 1408 537 -6
0.3872 0.93 8 7] 14 15 532 -7
0.4980 0.93887 1423 526 -6
0.5877 0.939 17 1431 52 1 -6
070 11 0. 93972 1440 5 13 - 5
() 8024 0.94027 1448 507 -4
0.8948 09-1075 14 -6 501 ,
- .'
h K E K E d K E d .. were " 2' .,1 3 an x23 enote excess IsentropIc
compress ibil it ies for the three binary mixtures and the e are estimated using the smoothing eq uation:
where, bo, b l and b2 are constants obtained by the methods of least squares. The binary parameters of excess isentropic compressibil ity fo r the binary mixtures of . N-dimethylformamide wi th l-alcohols3 and cyc lopentanone with l-alcohols2 1 were taken from literature. Further, the excess isentropic compressibi I ities for the system N, N-d imethylfonn am ide with cyc lopentanone, whi ch are not availab le in li terature have been determined experimenta ll y in th e present investigat ions.
K r: fo r thi s binary system exhi bi ts negati ve deviati on
from idea l behav iour of the entire range of the composit ion. The data are presented in Table 2 and graphical ly
represented in Fig. I . The negat ive K: values indicate
that the contri bution made by dipolar interact ions between unli ke molecul es of the components are predominant. The binary parameters for a ll the binary systems are presented in Table 3. The experimental data for four ternary mi xtures are listed in Tab le 4.
Tnble 3 - Values of paramcters ho. in. b2 and standa rcl devia tion
cr(/\ : ') for binary systems a l :03 . 15 K
Systcm s"
.N-<Iimclily lfo rmam id.: - 25 .2 ( I ) , C) clop.:nlanonc (2)
6 .0
N. r-<lirlll;lhy lfo rrna mid.: - 225. 6 35.6 ( 1) + l-propnno l (3)
I .N-<li methy lform.llnid.: - 92 .3 (I) ~ I-bll tano l (3)
N. - d imcthy lfo rlllam ick 37.2 ( 1 ) ~ I-pcnlanol n)
.1 k:' data for Ih .: mi :\ turcs uf cyclop.:nlanonc \\ ith l-h<':X3I1ol Jr~
.:Ios.: 10 <.:xp<:r il11cntal error" I and an: not s ho\~n in the Tabk.
VENKA TESU et al.: ULTRASONIC VELOCITIES OF TERNARY MIXTURES Table 4 - The values of density (p), ultrasonic velocity (U), isentropic compressibility (Ksl 23) and its related properties for
N, N-dimetylformamide (I) + cyclopentanone (2) + l -alkanols (3) at 303. 1 4 K
