ISSN: 2229-3701
International Journal of Research in Pharmaceutical and Biomedical Sciences
___________________________________________Research Article
Molecular Interactions Studies of Methanol and Ethanol in Non-Polar
Solvent System
P.Krishnamurthi, T.Vasavi
Department of Physics
Jayam College of engineering & Technology, Dharmapuri, Taminadu, India.
_____________________________________________________________________________________________
Abstract
The densities and refractive index of binary mixtures of methanol with carbon tetrachloride, benzene,
chlorobenzene and 1, 4 dichlorobenzene have been measured at room temperature. The data have been utilized
to compute the excess volumes and molar refraction. The results have been interpreted in terms of molecular
interactions existing between the components of the mixtures.
Keywords: Excess molar volume, molar refraction, density, refractive index, Molecular interactions
1.
Introduction
The thermodynamic properties like molar volume,
molar refraction, etc., are very useful tools in
understanding inter molecular interaction between
like and unlike molecules from the nature and
structure of the molecules. 1- 5 In the present study the
binary mixture of methanol and ethanol with benzene
(BE), carbon tetrachloride (CT), chlorobenzene (CB)
and 1,4 dichlorobenzene (DCB) .The thermodynamic
properties of methanol and ethanol with above
solvent have been studied over the entire composition
range at 301 K
2.
3.
Theory
The excess molar volume (VE) can be computed from
experimental density data using the relationship.
VE =V12 - (V1 +V2 )
Experimental
The whole chemical used was of A. R. grade with
purity >99% were used. The purity of liquid was
checked by comparing experimental values of
densities and refractive index of these liquids [6-7].
Binary mixtures were prepared by mixing a known
mass of each liquid in an airtight, stopper glass bottle.
Refractive
indices
were
measured
using
thermostatically controlled Abbe refractometer with
accuracy 0.001 units. Calibration was performed by
measuring the refractive indices of doubly distilled
water at defined temperatures within 0.01 K. The
masses were recorded on digital balance Aux 220
series to an accuracy of ± 1×10-4 g. Care was taken to
avoid contamination during mixing.
In this present study a specific gravity bottle 25ml
was used for the density measurements. The specific
gravity bottle was calibrated with freshly prepared
Vol. 4 (1) Jan– Mar 2013
triply distilled water. The density measurements for
each experimental liquid were repeated three to four
times. This procedure enabled us to get an
uncertainty of ±5x10-4 gm/cm3 in density
measurements.
m x
i
Since V12 =
i
ρ12
…(1)
i
and
Vi =
mi
ρi
Where xi, mi and ρi designate the mole fraction, the
molecular weight and the density of the ith
component.
ρ12
is the density of mixture.
The excess refractive index (n) values were
calculated from refractive index of the solution using
the following equation,
nE=n12-(n1+n2)
…(2)
The molar refraction (R) were calculated using the
relation using Lorentz-Lorentz equation
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International Journal of Research in Pharmaceutical and Biomedical Sciences
 n 2 -1   m 
R12 =  2   12 
 n +2   ρ12 
…(3)
The excess molar refraction gives more information
than the excess refractive indices about the molecular
interaction process because it take into account
electronic perturbation of molecular orbital during
the liquid mixtures process and R also directly related
to the dispersion forces.
RE=R12-(R1x1+ R2x2)
4.
…(4)
Results and Discussion
The values of refractive index (n12) and density ( ρ12 )
for the binary mixtures of methanol and ethanol with
solvent
(Benzene,
carbon
tetrachloride,
chlorobenzene and 1, 4 dichlorobenzene at 301 K are
presented in Table 1. From the table it was noticed
that the n12 increase and ρ12 decreases with
increasing concentration of methanol and ethanol.
Figure 1 and 2 shows the variation of excess
refractive index (nE) values for the binary mixtures of
methanol and ethanol with benzene, carbon
tetrachloride,
chlorobenzene
and
1,
4
dichlorobenzene at 301 K. From the figure 1 and 2
nE values shows complete positive for all the binary
mixtures. These values follow the order
dichlorobenzene >
carbon
tetrachloride >
chlorobenzene > benzene.
ISSN: 2229-3701
Figure 3 and 4 shows the variation of excess molar
refraction (RE) values for the binary mixtures of
methanol and ethanol with benzene, carbon
tetrachloride
,
chlorobenzene
and
1,4
dichlorobenzene at 301 K. From the figure excess
molar refraction (RE) shows complete positive for all
the binary mixtures. These values fall in the order
dichlorobenzene
>carbon
tetrachloride
>
Chlorobenzene > benzene.
Figure 5 and 6 shows the variation of excess molar
volume (VE) values for the binary mixtures of
methanol and ethanol with benzene, carbon
tetrachloride,
chlorobenzene
and
1,
4
dichlorobenzene at 301 K. From the figure VE shows
complete positive value for all the binary mixtures.
These values in the order of dichlorobenzene >carbon
tetrachloride > chlorobenzene > benzene.
The positive values of the excess parameter (nE,
RE,VE) are observed in all the binary mixtures
indicate that exist solute-solvent interaction arises
due to the dispersion forces8-10. Methanol or ethanol
as one of component, the order of solute – solvent
interactions are benzene > chlorobenzene > carbon
tetrachloride > dichlorobenzene.
5.
Conclusions
The refractive index, density and related excess pure
liquids and binary mixtures have been reported. In
the mixtures the refractive index increases and
density decreases with increasing concentration
methanol and ethanol. The excess parameter shows
the solute-solvent interaction as in the order of
benzene > chlorobenzene > carbon tetrachloride >
dichlorobenzene.
Table 1 Experimental data of ρ , η and calculated R, V of pure liquids at 301 K
Liquids
Benzene
Carbon tetrachloride
Chlorobenzene
1,4 dichlorobenzene
Methanol
Ethanol
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ρ
gm/cm3
0.8680
1.5950
1.1100
1.2500
0.792
0.868
n
R
V
1.501
1.4601
1.5247
1.5434
1.328
1.501
26.51
26.42
31.06
37.09
8.2077
12.92
89.98
96.46
101.40
117.60
40.45
58.39
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127
International Journal of Research in Pharmaceutical and Biomedical Sciences
ISSN: 2229-3701
Table 2 Experimental values of density ( ρ12 gm/cm3) and refractive index of methanol and ethanol
with solvent systems at 303 K
Methanol
BE
X2 /
Solvent
CT
n12
ρ12
CB
n12
ρ12
DCB
n12
ρ12
n12
ρ12
0.0476
0.86438
1.4932
1.5593
1.4545
1.0965
1.5169
1.2331
1.536
0.0735
0.86241
1.489
1.5397
1.4514
1.0891
1.5125
1.2238
1.5319
0.1010
0.86032
1.4844
1.5188
1.4481
1.0812
1.5079
1.2137
1.5274
0.1303
0.8581
1.4796
1.4966
1.4446
1.0727
1.5029
1.2029
1.5226
0.1615
0.85573
1.4744
1.4727
1.4408
1.0636
1.4976
1.1911
1.5174
0.2306
0.85047
1.4629
1.4195
1.4323
1.0432
1.4855
1.1645
1.5055
0.3101
0.84443
1.4496
1.3577
1.4223
1.0193
1.4713
1.1328
1.4912
0.4027
0.83739
1.4338
1.285
1.4106
0.9909
1.4542
1.0941
1.4736
0.5119
0.8291
1.4151
1.1978
1.3963
0.9567
1.4332
1.0461
1.4514
0.6426
0.81916
1.3923
1.0919
1.3788
0.9145
1.407
0.9848
1.4226
0.8018
0.80706
1.364
0.9602
1.3567
0.8613
1.3732
0.9038
1.3837
Ethanol
0.0672
0.8627
1.492
1.5442
1.4541
1.0907
1.5154
1.2259
1.5344
0.1027
0.8599
1.4872
1.5172
1.4508
1.0804
1.5103
1.2128
1.5295
0.1396
0.857
1.4823
1.4891
1.4475
1.0696
1.5051
1.1991
1.5243
0.1778
0.854
1.4771
1.4597
1.4439
1.0583
1.4996
1.1845
1.5188
0.2176
0.8508
1.4717
1.429
1.4402
1.0465
1.4937
1.1691
1.513
0.302
0.8441
1.4601
1.3633
1.4323
1.021
1.4811
1.1353
1.5001
0.3935
0.8369
1.4475
1.2911
1.4235
0.9927
1.467
1.097
1.4854
0.4932
0.829
1.4337
1.2114
1.4138
0.9612
1.4511
1.0532
1.4683
0.6022
0.8204
1.4183
1.1231
1.4029
0.926
1.4331
1.0026
1.4484
0.7219
0.811
1.4013
1.0246
1.3907
0.8862
1.4126
0.9434
1.4247
0.8538
0.8005
1.3824
0.914
1.3768
0.8409
1.3888
0.8733
1.3961
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128
International Journal of Research in Pharmaceutical and Biomedical Sciences
ISSN: 2229-3701
Fig.1 Plots of nE Vs mole fraction of methanol (x2) with solvent systems
Fig.2 Plots of nE Vs mole fraction of ethanol (x2) with solvent systems
Fig.3 Plots of RE Vs mole fraction of methanol (x2) with solvent systems
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International Journal of Research in Pharmaceutical and Biomedical Sciences
ISSN: 2229-3701
Fig.4 Plots of RE Vs mole fraction of ethanol (x2) with solvent systems
Fig.5 Plots of VE Vs mole fraction of methanol(x2) with solvent systems
Fig.6 Plots of VE Vs mole fraction of ethanol(x2) with solvent systems
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International Journal of Research in Pharmaceutical and Biomedical Sciences
ISSN: 2229-3701
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