The document discusses physicochemical properties of binary liquid mixtures of DMSO with methanol, ethanol, n-propanol, and n-butanol at different temperatures. It describes measuring the density, viscosity, refractive index, and dielectric constant of the mixtures at varying compositions and temperatures. The results show that DMSO and methanol form the least ordered system with the highest excess entropy of activation, while DMSO and n-butanol are the most ordered. The document concludes that addition of alcohols to DMSO ruptures the hydrogen-bonded structures of the alcohols, with mainly non-specific interactions present between the non-identical components.

1. Exam. Roll: CURZON-1501
Registration No: HA-2639( 2009-10)
M.S. SESSION : 2013-14
DEPARTMENT OF CHEMISTRY
UNIVERSITY OF DHAKA
Physicochemical properties of the binary mixtures
of DMSO with methanol , ethanol , n–propanol and
n–butanol at different temperatures

2. Importance of physicochemical properties of
binary liquid mixtures
 The study of physicochemical properties of binary
liquid mixture provides the way of accumulation of
knowledge about the types of interaction in a binary
mixture of different substances.
 It may show the appearance of a new phenomenon,
which is absent in pure state.
The talk is about…
Binary Liquid Mixtures

3.  Dissolves both polar and nonpolar compounds and miscible in a
wide range of organic solvents as well as water.
 As, DMSO is only weakly acidic, it tolerates relatively strong
bases.
 Because of its high boiling point, 189 °C, DMSO evaporates
slowly at normal atmospheric pressure. Samples dissolved in
DMSO cannot easily escape compared to other solvents.
Why DMSO?
 The hydroxyl group makes the alcohol molecule polar and can
form hydrogen bonds to one another and to other compounds.
This hydrogen bonding means that alcohols can be used as protic
solvent.
 Two opposing solubility trends in alcohols are the tendency of the
polar OH to promote solubility in water, and the tendency of the
carbon chain to resist it.
Why alcohol?

4. Objective of the research
Preparation of binary liquid mixtures of DMSO with methanol,
ethanol, n–propanol and n–butanol.
 Determination of density, viscosity, refractive index and dielectric
constant of these binary liquid mixtures over the entire range of
composition at five different temperatures.
 Determination of interaction parameter, some thermodynamic
properties such as free energy of activativation, enthalpy and
entropy of activation and excess properties of all those mentioned
properties from experimental data over the entire range of
composition.
Study of types of intermolecular interactions present in these
binary mixtures and the strength of interaction betwen the
components.
 Comparison of different physicochemical properties of these
binary mixtures.

5. Experimental
Measurement of Density: The densities of the pure
components and their binary mixtures were measured
with Anton Paar (model DMA 4500) vibrating tube
density meter, which is being excited to vibrate at a
characteristic frequency. Through a precise determination
of this frequency and a mathematical conversion, the
density of sample can be measured.
Measurement of Dielectric constant: Dielectric constant
was directly measured by ALPHA DCM 470 Dielectric
constant meter.

6. Measurement of Viscosity: The viscosities of the pure
components and their binary mixtures were measured with
Lovis 2000 M/ME Microviscometer which measures
viscosity by rolling ball principle. In the rolling ball
principle, a ball rolls through a closed, liquid-filled capillary,
which is inclined at a defined angle. Three inductive sensors
determine the ball's rolling time between defined marks. The
sample's viscosity is directly proportional to the rolling time.

7. Measurement of Refractive index: The refractive indices of the
pure components and their binary mixtures were measured with
Anton Paar (model- Abbemat 300/500) Refractometer. The
sample on top of the measuring prism is irradiated from different
angles by an LED. At the interface between sample and prism the
incident beam is either refracted into the sample or reflected back
to into the prism. The reflected beam is detected by a sensor
array. From this the critical angle for total reflection is calculated
and used to determine the refractive index (RI) of the sample.

8. Density of the binary systems of DMSO with alcohols
at 298.15 K

9. Excess density of the binary systems of DMSO with
alcohols at 298.15 K
dE =dobs. – dcal dcal. = x1d1 + x2d2

10. Molar volume of the binary system of DMSO with
alcohols at 298.15K
Vmix = ( x1M1 + x2M2 ) / dmix

11. Excess molar volume of the binary systems of DMSO
with alcohols at 298.15K
Vm
E = Vm - ( x1V1
0 + x2V2
0 )

12. Viscosity of the binary systems of DMSO with alcohols
at 298.15 K

13. Excess viscosity of the binary systems of DMSO with
alcohols at 298.15K
ηE = ηobs - ηid

14. Interaction parameter of the binary systems of DMSO with
alcohols at 298.15 K
ηid= exp( x1ln η1 + x2ln η2+ x1x2ε)ε =
21
)ln(ln
xx
idobs  

15. Free energy of activation of the binary systems of DMSO
with alcohols at 298.15K
ln(η Vm / hN) = -ΔS# / R + ΔH# / RT ΔH# = slope x R
ΔS# = - intercept x R
ΔG# = ΔH# - TΔS#

16. Excess free energy of activation of the binary systems
of DMSO with alcohols at 298.15K
ΔG#E = ΔG# – (x1 ΔG0# +x2 ΔG0#)

17. Enthalpy of activation of the binary systems of DMSO
with alcohols

18. Excess enthalpy of activation of the binary systems of DMSO
with alcohols
ΔH# E = ΔH# – (x1ΔH#
1+x2ΔH#
2)
 DMSO + methanol ˃ DMSO + ethanol ˃ DMSO + n-propanol ˃ DMSO + n-butanol
 This trend is seemed to be inconsistent with the chain length of the alcohols

19. Entropy of activation of the binary systems of
DMSO with alcohols

20. Excess Entropy of activation of the binary systems of
DMSO with alcohols
ΔS# E = ΔS# – (x1ΔS#
1+x2ΔS#
2)
 Excess entropy is in the order of the binary systems of DMSO with methanol ˃
ethaanol ˃ n-propanol ˃ n-butanol
 So, n-butanol + DMSO is the most ordered and n-methanol + DMSO is the least
ordered system in viscous flow

21. Refractive index of the binary systems of DMSO with
alcohols at 298.15K

22. Excess Refractive index of the binary systems of DMSO
With alcohols at 298.15 K
nE=nobs. –ncal. ncal. = x1n1 +x2n2

23. Dielectric constant of the binary systems of DMSO with
alcohols at 298.15K

24. Excess Dielectric constant of the binary systems of
DMSO with alcohols
εE = ε12 - (ε1X1 + ε2X2) εE = εobserved –εideal

25. CONCLUSION
 Upon addition of alcohols to the DMSO, rupture of H-
bonded structure of these alcohols occurs.
 There are mainly non-specific interactions present among
the non-identical components of the systems but in case of
the binary system of methanol and ethanol with DMSO
weak interaction( small magnitude of H-bond) may occur.

26. Thank you

29. Supporting Slides