International Journal of Scientific & Engineering Research, Volume 6, Issue 5, May-2015 65
ISSN 2229-5518
Thermodynamic parameters of medicine with
Ethanol
Dr Sharmila Chaudhari
P.D.E.A.'s Baburaoji Gholap College,New Sanghvi,Pune -27,India
Abstract— The information related to the solute-solvent interaction has been carried out related to thermodynamic properties like activation en- ergy, conductivity, enthalpy entropy etc in the mixture of Ayurvedic Medicine-Dashmularishta and ethanol. Dielectric relaxation study of Dashmular- ishta used in gynaec problems has been carried out at 150C, 250C, 350C and 45 0C in the frequency range 10MHz to 20GHz for 11 different concentrations of the system. Time Domain Reflectometry (TDR) Technique in reflection mode has been used to measure Thermodynamic pa- rameters viz activation energy, conductivity, enthalpy entropy etc.Further, Fourier transforms and least square fit method has been used to obtain Thermodynamic parameters. W ith change in concentration and temperature, the systematic changes in Thermodynamic parameters are ob- served.
—————————— ——————————
drive.
The temperature controller system with water bath and a
The dielectric relaxation study at microwave frequency gives
information about solute- solvent interaction and liquid struc-
ture of mixture. In this study, Ayurvedic medicine- Dashmu-
Time Domain Reflectometry in reflection mode has been used
to obtain thermodynamics parameter. The objective of the pre-
sent paper is to report the dielectric relaxation study of above
system using TDR in the temperature range 150C to 450C.
thermostat has been used to maintain the constant tempera-
ture within the accuracy limit of ±1 0C. The sample cell is sur-
rounded by a heat insulating container through which the wa-
ter of constant temperature using temperature controller sys-
tem is circulated. The temperature at the cell is checked using
the thermometer.
Kauzmann has given an extensive analysis of di- pole orientation as a rate phenomenon. Eyring14 consid- ered that dipole orientation involves passage over a po- tential energy barrier with a certain probability of jump- ing from one orientation to another. He obtained the po- larization P(t), as a function of time as
The Thermodynamic parameters were obtained by using the
Time Domain Reflectometry method. The Hewlett Packard
P(t ) = P0
e − ko t
(1)
HP54750 sampling oscilloscope with HP 54754A TDR plug in-
module has been used. A fast rising step voltage pulse of
about 200 mV amplitude and 43.8486 ns rise time with repeti-
tion frequency of 12.4 GHz is generated and is propagated
through a coaxial transmission line. The sample is placed at
the end of the coaxial transmission line in a standard Military
where, P0 is orientation polarization at t = 0;
k0 is the rate constant for the activation of dipole,
i.e. mean number of jumps made by a dipole in unit
time.
When t is such that k0 t = 1, P(t) must have decayed to
P0 /e. This value of t is a relaxation time, which may be
application (SMA) coaxial cell. The SMA cell used for this
defined as
τ =1 / k 0 . (2)
work had 3.5 mm outer diameter and 1.33 mm effective pin
length. The step pulse generated by tunnel diode and the
pulse which is reflected from the sample cell were sampled by
a sampling oscilloscope in the time window of 1.3 ns. The re-
flected pulse without sample R1 (t) and with sample Rx (t) av-
eraged 64 times and digitized with 1024 points in oscilloscope
memory and transferred to PC through a 1.44 floppy diskette
The process of molecular orientation requires an
activation energy sufficient to overcome the energy barrier
separating the two mean equilibrium positions. The num-
ber of times such a rotation will occur per second is giv-
en by the rate expression -
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International JourknTal of Scientific & Engineering Research, Volume 6, Issue 5, May-2015 66
IkSS0N=22129/-τ55=18
h
e −∆F / RT
(3)
lectric loss ε" , however, is a parameter which describes the motion of the charge i.e. conduction. Certain thermo- dynamicss are found to display conduction because of
where h is Plank's constant;
charge transport i.e. ionic conduction in electrolytes. This
∆F
relaxation.
is molar free energy of activation for dipole
conduction normally be described by a volume conductiv-
ity σ (mho/m). It is σadditive to dielectric loss, ε" , so that-
Since
∆F = ∆H − T∆S , (3.a)
ε" = ε"dielectric + ωε
(6)
τ = h kT
e ∆H / RT
e − ∆S / R
(4)
The frequency variation of thermodynamics loss is given by
where
∆H is the enthalpy(heat) of activation for dipole - ( )
relaxation and
ε = ε s − ε ∞ ωτ
tion.
∆S is the entropy of activation for dipole relaxa-
"
1 + ω 2τ 2
The entropy of activation
∆S may be calculated since
∆F is now known from eq. (3.a), and ∆H
is obtained = σ
from the slope of the curve for
1/T.
Eq. (4) can be rewritten as -
ln (τT) plotted against
so that -
ε 0 ω
(ε − ε )ω2 τ ε
σ = s ∞ 0
ln (τT) = ∆H + A RT
(5)
1+ ω2 τ 2
If σ ∞ is conduc(tivity at hi)gh frequency given by -
h
∆S
σ ∞ =
ε s − ε ∞
/ τ , we obtain -
A = ln
−
where
k
R
σ ω2 τ 2
σ = ∞
In eq. (4),
∆H / R , is the slope of
ln (τT)
v/s
1 + ω2 τ 2
1/T. If
∆H and
∆S are independent of temperature, then
plot of
ln (τT)
v/s 1/T is linear. The slope
∆H / R gives
(8)
the height of potential barrier. Differentiating eq. (3.a)
gives -
This equation describes the elevation of dielectric
conductivity from its zero value at zero frequency to a
value σ ∞
at infinite frequency. The form of this elevation
∆H =
d [ln (τT )]
R
d [1 / T ]
− RT
(6)
is similar to the form of the fall of the real part of the thermodynamics constant. If a static conductivity term σs is added, we get -
Thermodynamic properties may be used to access the dipole under the influence of applied field. The acti-
(σ ∞ − σ s
)ω 2 τ 2
vation energy for every compound increases as the tem- perature increases, whereas the relaxation time decreases. This may be due to decreased viscosity of medium . With
σ = σ s
+
1 + ω 2 τ 2
(9)
increase in temperature the thermal agitation increases and dipole requires more energy in order to attain the equilibrium with the applied field. The molar free energy of activation is greater than the molar enthalpy of activa- tion, which results into negative values of enthalpy. This indicates that the activated state is more ordered than the normal state, which is true as in the activated state, and the dipoles try to align with the applied field.
Experiments designed to measure high frequency conductivity for bio-molecular solutions, confirms this re- lationship.
ε* =
Dispersion in conductivity
The complex thermodynamics constant,
ε' − i ε" , which is dimensionless quantity. The die-
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International Journal of Scientific & Engineering Research, Volume 6, Issue 5, May-2015 67
ISSN 2229-5518
Punarnavarishta ε' Punarnavarishta ε" Methanol ε'
80 Methanol ε"
70
60
50
40
30
20
10
0
0.01 0.1 1 10
Frequency (GHz)
Figure.A: Corrected data for Dashmularishta + Methanol mixture at 350
40 Punarnavarishta
Methanol
35
30
25
20
15
10
5
0
0 10 20 30 40 50 60 70 80
ε'
Figure.B: Cole –Cole plot for Dashmularishta + Methanol.
1.0
0.9
0.8
0.7
0.6
Ideal
150C
250C
350C
450C
0.5
0.4
0.3
0.2
0.1
0.0
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
Vol. fraction of Ethanol
Figure C : Variation of Bruggeman factor
0.24
0.22
0.20
0.18
0.16
0.14
0.12
0.10
0.08
0.06
0.04
0.02
0.00
-0.02
15oC
25oC
35oC
45oC
0 20 40 60 80 100
Volume Fraction of Ethanol
Figure D:Variation for Dashmularishta for vol
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International Journal of Scientific & Engineering Research, Volume 6, Issue 5, May-2015 68
ISSN 2229-5518
22 150C
250C
20 350C
450C
18
16
14
12
0.0 0.2 0.4 0.6 0.8 1.0
Volume fraction of Ethanol
Figure G: Variation of free energy of activation for
Dashmularishta + Ethanol
18
-16.5 100 % Ethanol
50 % Ethanol + 50 % Dash.
16 100 % Dashmularishta
-17.0
14
-17.5
12
-18.0
10
8
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
Vol. fraction of Ethanol
-18.5
-19.0
3.10 3.15 3.20 3.25 3.30 3.35 3.40 3.45 3.50
1000/T
Figure E: Variation of Enthalpy for Dashmularishta + Ethanol
0.000 ∆S
-0.002
Figure H:Arrehenius plot for Dashmularishta+Ethanol
-0.004
-0.006
-0.008
-0.010
-0.012
-0.014
-0.016
-0.018
-0.020
0.0 0.2 0.4 0.6 0.8 1.0
Volume fraction of Ethanol
Figure F: Variation of entropy for Dashmularishta+Entropy
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International Journal of Scientific & Engineering Research, Volume 6, Issue 5, May-2015 69
ISSN 2229-5518
2. M. T. Hosamani, R. H. Fattepur, D. K. Deshpande and
S. C. Mehrotra, J.Chem.soc. Faraday Trans91 (4) (1995)
623.
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7. U. R. Lahane ,Structural Molecular Study of Ayurve- dic Medicines Using Dielectric Relaxation Tech.- Ph.D. Thesis ,Feb.(2003)
Bruggeman factor is used as first evidence of molecular interaction .This formula states the static permittivity ofthe mixtures which are related to volume fraction. The realationship between Bruggeman factor and V shows devaition which indicates molecular interact ion and can be observed practically. The values of Bruggeman factor shows repulsive force,attractive force and ideal situations.
Activation energy shows the dynamics of solute-solvent interaction,rotation of effective dipoles,etc.The activation en- ergy for every compound increases as the temperature in- creases,whereas the relaxation time decreases. This is due to decreased viscosity of the medium,which also indicates the activated state is more ordered than the normal one ,as the dipoles try to align with the applied field. The dielectric loss is a parameter which describes the motion of charge,that is conductivity.
Certain dilelectrics are found to display conduction due to charge tranfer,i.e. volume conductivity.
1. A.C. Kumbharkhane, S. M. Puranic and S. C. Mehro- tra, J. Solution Chemistry20 (1991)12.
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