Download CHAPTER -IX Apparent Molar Volumes and Viscosity

CHAPTER -IX
Apparent Molar Volumes and Viscosity B-Coefficients of Mineral
Salts in Aqueous 2-Methoxy ethanol Solutions at T = 298.15 K
9.1. Introduction
Mineral salts are naturally-occurring elements needed by the body for its
vital activities. Each mineral, with its own specific task, even in the small and often
minute quantities necessary, is indispensable for important life functions; they are
needed for the formation of hormones, enzymes and other body substances.
They’re generally found in foods in the form of chemical compounds called salts and
in water in the form of ion soluble. They are needed in very small amounts, or
traces, in the diet, and hence their name, "trace minerals. Sodium nitrate is used as
an ingredient in fertilizers, pyrotechnics, as an ingredient in smoke bombs, as a food
preservative, as a solid rocket propellant, and as in glass and pottery enamels.
Potassium nitrate is a strong oxidizer which burns and explodes with organics. It is
used in the manufacture of gunpowder. It is also used in explosives, fireworks,
matches, and fertilizers, and as a preservative in foods especially meats. It is
sometimes used in medicine as a diuretic. Potassium nitrate prill type is mainly used
to produce kinescope, optics glass, high grade craft glassware .Lithium nitrate is
used as an electrolyte for high temperature batteries. It is also used for long life
batteries as required, for example, by artificial pacemakers. The solid is used as a
phosphor for neutron detection.
2-Methoxy Ethanol finds a wide range of
application 1, namely as a solvent and solubilizing agent in many industries
Studies on densities (ρ) and viscosities (η) of electrolyte solutions are of
great importance in characterizing the properties and structural aspects of
solutions. The addition of an electrolyte to an aqueous organic solution alters the
pattern of ion solvation and causes phenomenal changes in the behavior of the
dissolved electrolyte. Hence studies on the limiting apparent molar volume and
viscosity–B coefficients of electrolyte provide us valuable information regarding ion-
Apparent Molar ……………… 2-Methoxy ethanol Solutions at T = 298.15 K
252
ion, ion-solvent and solvent-solvent interactions 2–4. It has been found by a number
of workers
5–7
that the addition of an electrolyte could either make or break the
structure of a liquid. As the viscosity of a liquid depends on the intermolecular
forces, the structural aspects of the liquid can be inferred from the viscosity of
solutions at various electrolyte concentrations. The studies of partial molar volumes
are of great help in characterizing the structure and properties of solutions. The
solution structure is of great importance in understanding the nature of the action
of bioactive molecules in the body system. The addition of an organic solvent to
water brings about a sharp change in the solvation of ions. The peculiarities of
aqueo-organic mixtures are well reflected in the dramatic changes in reaction rates
8, 9
and medium effect or free energies of transfer of ions which cannot be explained
on the basis of change in the dielectric constants of the solvent mixtures alone. As
the partial molar volume of a solute reflects the cumulative effects of ion–ion and
ion–solvent interactions, it would be of interest to study the partial molar volumes
of Mineral salts, viz. sodium nitrate, potassium nitrate and lithium nitrate in the
binary aqueous mixtures of 2-methoxy ethanol. Such data are expected to highlight
the role of mineral salts in influencing the partial molar volumes in mixed solvent
systems. These considerations prompted us to undertake the present study
9.2. Experimental Section
Materials
Sodium nitrate (Ranbaxy, >98.0%) was crystallized from hot water, cooled to
00C and dried under vacuum at 1400C, potassium nitrate (S.D. fine Chemicals,
>99.5%), was crystallized from hot water, cooled and dried for 12hr under vac. at
700C. Lithium nitrate (Thomas Baker, >98%) was crystallized from ethanol and
dried at 1800C for several days by repeated melting under vac. The anhydrous salt
was dried at 1200C and stored in a vacuum desiccator over calcium Sulphate. 2methoxy ethanol (SRL, India, >99.5%) was refluxed with stannous chloride. It was
dried with silica gel and finally distilled with sodium. De-ionized, doubly distilled,
degassed water with a specific conductance of 1· 10 −6 S ⋅ cm −1 was used for the
Apparent Molar ……………… 2-Methoxy ethanol Solutions at T = 298.15 K
253
preparation of different aqueous 2-methoxy ethanol solutions. The physical
properties of different aqueous 2-methoxy ethanol solutions are listed in Table 1
Apparatus and Procedure
The density, ρ , was measured with an Anton Paar density-meter (DMA
4500M). The uncertainty in the density measurements is within ± 5·10-5 g·cm-3. It
was calibrated by double-distilled water and dry air. The viscosity,η , was measured
by means of suspended Ubbelohde type viscometer, calibrated at the experimental
temperatures with doubly distilled water and purified methanol. A thoroughly
cleaned and perfectly dried viscometer filled with experimental solution was placed
vertically in a glass-walled thermostat (Bose Panda Instruments Pvt. Ltd.)
maintained to ± 0.01 K. After attainment of thermal equilibrium, efflux times of flow
were recorded with a stop watch correct to ± 0.1 s. At least three repetition of each
data reproducible to ± 0.1 s were taken to average the flow time. Viscosity of
solution,η, is given by the following equation:
η = (Kt − L / t)ρ
(1)
where K and L are the viscometer constants and t and ρ are the efflux time of flow in
seconds and the density of the experimental liquid, respectively. The uncertainty in
viscosity measurements is within ± 0.003 mPa·s. The electrolyte solutions studied
here were prepared by mass. The experimental values of molality, densities,
viscosities, apparent molar volume and
(ηr − 1)
are reported in Table 2.
m
9.3. Results and Discussion
The apparent molar volumes ( φV ) were determined from the solution
densities using the following equation10:
φV = M ρ − 1000(ρ − ρ0 ) mρρ0
(2)
where M is the molar mass of the solute, m is the molality of the solution, ρ 0 and ρ
are the densities of the solvent and the solution respectively. As the plots of
Apparent Molar ……………… 2-Methoxy ethanol Solutions at T = 298.15 K
254
φV values against square root of molality ( m ) were linear, φV values were fitted to
the Masson equation 11:
φV = φV0 + SV* m
(3)
where φV0 is the limiting apparent molar volume at infinite dilution, SV* is the
experimental slope and m is the molality of the solution. The φV0 values have been
determined by fitting the dilute data (m < 0.1mol·kg-1) to eq.3 using a weighted least
square fit.
The standard deviation ( σ ) were determined from φV0 values using the
following equation:
σ =
∑ (Y exp − Ycal)
N −1
2
( 4)
where Y is the limiting apparent molar volume of the solution ( φV0 ) and N is
the number of data points.
Values of φV0 and SV* along with the corresponding standard deviation ( σ ) are listed
in Table 3. The estimated uncertainties in φV0 are equal to standard deviation ( σ ),
the root mean square of the deviation between the experimental and calculated φV0
for each data point. A perusal of Table 3 and Figure 1-3 reveals that the φV0 values of
studied salts are positive and increases with rise in the mass percent of 2-methoxy
ethanol in the solvent mixture. This indicates the presence of strong ion–solvent
interactions and these interactions are strengthened at higher concentrations of 2methoxy ethanol in the solvent mixture. It may be concluded that for all the studied
solvent mixtures that the salts are rather solvated than hydrated by 2-methoxy
ethanol and the solvation of the salts with the increasing concentration of 2 methoxy
ethanol follows the order:
K+ > Na+ > Li+
The same results were observed for some thiocyanate in aqueous 1,3-dioxolane
mixture 12,13.
Apparent Molar ……………… 2-Methoxy ethanol Solutions at T = 298.15 K
255
Table 3 and Figure 4-6 also reveals that SV* values are negative for all the
solutions and SV* values decrease as the amount of 2-methoxy ethanol in the
mixtures increases. Since SV* is a measure of ion–ion interactions, the results
indicate the presence of weak ion–ion interactions in the solutions at all
experimental temperatures, and these interactions further decrease with a rise in
concentration of 2-methoxy ethanol in the mixtures. In other words, it may be said
that the solvation of electrolyte/ions increases with an increase of 2-methoxy
ethanol content in water. This is probably due to moderate dielectric constants 14 of
the aqueous 2-methoxy ethanol mixtures, resulting in diminishing ion–ion
interactions (ionic dissociation) 15. Here, the structure and properties of mixture as
solvent plays an important role. Dielectric constant of pure 2-methoxy ethanol is
17.65, that of water 78.35 and that of mixture is between these two values.
According to the coulombic law of ion-ion interactions are stronger at lower
dielectric constant. These negative values of SV* in different compositions of 2methoxy ethanol + water also suggest the presence of cation–anion penetration
16
and this happens due to the competition between the ions to occupy the void space
of the large solvent molecules.
A quantitative comparison of the magnitude of values shows φV0 values are
much greater in magnitude than SV* values, for all the solutions. This suggests that
ion-solvent interactions dominate over ion–ion interactions in all the solutions.
Partial molar volumes ∆φV0 of transfer from water to different aqueous 2methoxy ethanol solutions have been determined using the relations 17,18.
∆φV0 = φV0 (Aqueous 2 − methoxy ethanol solution) − φV0 (Water)
(5)
The ∆φV0 value is independent of ion-ion interactions and therefore provides
information regarding ion-solvent interactions 17. It can be seen from Table 5, Figure
7-9 that the value of ∆φV0 is positive and increases monotonically with mass percent
of 2-methoxy ethanol in the remaining mixture. These results further confirm the
presence of strong ion-solvent interaction in the chosen solvent mixture for mineral
Apparent Molar ……………… 2-Methoxy ethanol Solutions at T = 298.15 K
256
salts. On the other hand with the increase of the size of the cation of the mineral
salts the ∆φV0 also increases i.e. the ion solvent interaction also increases with the
increases of the size of cation of the mineral salts.
The viscosity data of the experimental solutions of carbohydrates have
been analyzed using the Jones–Dole equation 19:
(η η0 − 1)
m = (ηr − 1)
m = A+ B m
(6)
where, the relative viscosity ηr = η η0 , η0 and η are the viscosities of the
solvent and solution, respectively, and m is the molality of a solution. A and B are the
Jones-Dole 19 constants estimated by a least-squares method and reported in Table
4. The values of the A coefficient are found to be smaller than the viscosity Bcoefficient and it decrease with increase in mass of 2-methoxy ethanol in the solvent
mixture. These results indicate the presence of very weak ion–ion interactions and
these interactions further decrease with an increase in mass percent of 2-methoxy
ethanol in solvent mixture. These results are in excellent agreement with those
obtained from SV* values.
The viscosity B-coefficient 20, 21 reflects the effects of ion–solvent interactions
on the solution viscosity. The viscosity B-coefficient is a valuable tool to provide
information concerning the solvation of solutes and their effects on the structure of
the solvent in the local vicinity of the solute molecules. From Table 4 it is evident
that the values of the B-coefficient of mineral salts in the studied solvent systems
suggests the presence of strong ion–solvent interactions, and these type of
interactions are strengthened with an increase of 2-methoxy ethanol in the solvent
mixtures. These conclusions are in excellent agreement with those drawn from
φV0 values discussed earlier.
The viscosity data have also been analyzed on the basis of transition state
theory for the relative viscosity of the solutions as suggested by Feakins et al.
22
using the relation,
∆µ20 ≠ = ∆µ10≠ + RT (1000 B + φ20 − φ10 ) / φ10
(7)
Apparent Molar ……………… 2-Methoxy ethanol Solutions at T = 298.15 K
257
where φ10 and φ20 are the limiting apparent molar volumes of the solvent and
solute, respectively. The contribution per mole of the solute to the free energy of
activation of viscous flow, ∆µ 20 ≠ of the solutions was determined from the above
relation and is listed in Table 6. The free energy of activation of viscous flow for the
solvent mixture, ∆µ10 ≠ , is given by the relation:
∆µ10≠ = ∆G10≠ = RT ln(η0 φ10 hN A )
(8)
where NA is the Avogadro’s number, ∆G10 ≠ is the Gibb’s free energy of viscous
flow, η0 is the viscosity of the solvent mixture, φ10 is the limiting apparent molar
volume of the solvent and h is the Planks Constant. The values of the parameters
∆µ10 ≠ and ∆µ 20 ≠ are reported in Table 6 and the values suggest that ∆µ10 ≠ is almost
invariant of the solvent compositions, implying that ∆µ20 ≠ is dependent mainly on the
viscosity B-coefficients and (φV0, 2 − φV0,1 ) terms. But ∆µ20 ≠ values were found to be
positive at all mass percent and this suggests that the process of viscous flow
becomes difficult as the size of the cation and mass percent of the 2-Methoxy
Ethanol increase. Hence the formation of the transition state becomes less favorable
22.
According to Feakings et. al
23
∆µ20 ≠ > ∆µ10 ≠ for solutes having positive
viscosity B-coefficients and indicates a stronger ion-solvent interactions, thereby
suggesting that the formation of transition state is accompanied by the rupture and
distortion of the intermolecular forces in solvent structure 22.
9.4. Conclusion:
In summary,
φV0 and viscosity B-coefficient values for studied mineral salts
indicate the presence of strong solute-solvent interactions and these interactions
are further strengthened at higher mass percent of 2-methoxy ethanol in the solvent
mixture. In case of potassium nitrate the solute-solvent interaction is greater than
the sodium nitrate and lithium nitrate respectly with higher mass percent of the 2methoxy ethanol in the solvent mixture.
Apparent Molar ……………… 2-Methoxy ethanol Solutions at T = 298.15 K
258
References
1.
G. Roux, G. Perron, J. E. Desnoyers, J. Solution Chem. 1978, 7, 639.
2.
J. M. Mc Dowali, C. A. Vincent, J. Chem. Soc. Faraday Trans. I, 1974, 1862.
3.
M. R. J. Dack, K. J. Bird, A. J. Parker, Aust. J. Chem. 1975, 28, 955.
4.
M. N. Roy, B. Sinha, R. Dey, A. Sinha, Int. J. Thermophys. 2005, 26, 1549.
5.
R. H. Stokes, R. Mills, Int. Encyclopedia of Physical Chemistry and
Chemical Physics, 1965.
6.
P. S. Nikam, H. Mehdi, J. Chem. Eng. Data 1988, 33, 165.
7.
D. Nandi, M. N. Roy, D. K. Hazra, J. Indian Chem. Soc. 1993, 70, 305.
8.
D. W. Wells, in: A. K. Covington, T. Dickinson (Eds.), Physical Chemistry
of Organic Solvent Systems, Plenum Press, London, 1973, Ch. 6.
9.
M. J. Blandamer, J. Burgess, B. Clark, P. P. Duce, A. W. Hakin, N. Gosal, S.
Radulovic, P. Guardado, F. Sanchez, C.D. Hubbard, E.A. Abu-Gharib, J.
Chem. Soc. Faraday Trans. I. 1986, 82, 1471.
10. E. Ayranci J. Chem. Eng. Data 1997, 42, 934.
11. D. O. Masson, Philos. Mag. 1929, 8, 218.
12. M. N. Roy, A.Choudhury, A. Jha, J. Chem. Eng. Data 2004, 49 291
13. M. N. Roy, R. Chanda, A. Banerjee, J. Chem. Eng. Data 2009, 54 (6), 1767.
14. P. R. Misra, B. Das, M. L. Parmar, D. S. Banyal, Indian J. Chem. 2005, 44,
1582.
15. F. J. Millero, Structure and Transport Process inWater and Aqueous
Solutions R. A. Horne, New York, 1972.
16. M. L. Parmar, S. Mahajan, Acta Cienc. Indica 1, 1984, 31.
Apparent Molar ……………… 2-Methoxy ethanol Solutions at T = 298.15 K
259
17. K. Belibagli, E. Agranci, J. Solution Chem. 1990, 19, 867.
18. Zhao, P. Ma, J. Li, J. Chem. Thermodyn. 2005, 37, 37
19. G. Jones, M. Dole, J. Am Chem. Soc. 1929, 51, 2950.
20. F .J. Millero The Molal Volumes of Electrolytes. Chem. Rev. 1971, 71, 147.
21. F. J. Millero, A. Lo Surdo, C. Shin, J. Phys. Chem. 1978, 82, 784.
22. D. Feakins, D. J. Freemantle, K. G. Lawrence, J. Chem. Soc., Faraday Trans.
I, 1974, 70, 795.
23. A. N. Campbell, R. J. Friesen, Can. J. Chem. 1959, 37, 1288.
24. M. Pilar Pena, Ernesto Vercher, and Antoni Martinez-Andreu J. Chem.
Eng. Data 1998, 43, 626.
Apparent Molar ……………… 2-Methoxy ethanol Solutions at T = 298.15 K
260
Table 1. Densities ( ρ ) and Viscosities (η ) of 2-Methoxy Ethanol (1) + Water (2)
Solutions at 298.15 K
Solvent mixtures
ρ .10-3 /kg ⋅ m −3
η/mPa ⋅ s
298.15
0.9993
1.1812
298.15
0.99832
2.3159
298.15
0.99712
2.9561
T(K)
10 mass % of 2-methoxy
ethanol + water
40 mass % of 2-methoxy
ethanol + water
70 mass % of 2-methoxy
ethanol + water
Table 2. Molalities ( m ), Densities ( ρ ), Viscosities (η ), Apparent Molar Volumes
( φV ) and (ηr − 1) / m for Mineral Salts in Different Molality (m1) of 2-methoxy
Ethanol (1) + Water (2) Solutions at 298.15 K
m / mol ⋅ kg -1
ρ ⋅ 10-3 /kg ⋅ m −3
η/mPa ⋅ s
φV ⋅ 106 / m 3 ⋅ mol −1
(ηr − 1)
m
10 mass % of 2-methoxy ethanol + water
Lithium nitrate
0.0225
0.0299
0.0525
0.0674
0.0824
0.0937
1.0002
1.0005
1.0014
1.0020
1.0026
1.0030
1.186
1.188
1.190
1.192
1.194
1.195
Sodium nitrate
29.41
29.32
29.20
29.07
29.03
28.92
0.0293
0.0322
0.0352
0.0370
0.0380
0.0382
0.0242
0.0323
0.0566
0.0727
0.0889
0.1010
1.0006
1.0010
1.0023
1.0032
1.0040
1.0046
1.187
1.189
1.192
1.195
1.196
1.198
Potassium nitrate
32.07
31.97
31.81
31.71
31.60
31.51
0.0320
0.0353
0.0390
0.0430
0.0420
0.0447
0.0240
0.0320
0.0560
0.0720
0.0881
0.1007
1.0007
1.187
42.32
1.0012
1.189
42.05
1.0026
1.193
41.69
1.0036
1.195
41.31
1.0046
1.197
41.07
1.0053
1.199
41.01
40 mass % of 2-methoxy ethanol + water
0.0340
0.0363
0.0415
0.0444
0.0460
0.0480
Lithium nitrate
0.0241
0.9993
2.327
29.97
0.0304
Apparent Molar ……………… 2-Methoxy ethanol Solutions at T = 298.15 K
261
0.0322
0.0563
0.0724
0.0885
0.1005
0.9996
1.0005
1.0012
1.0018
1.0023
2.330
2.338
2.341
2.345
2.346
Sodium nitrate
29.88
29.57
29.43
29.31
29.25
0.0340
0.0396
0.0410
0.0425
0.0418
0.0240
0.0320
0.0560
0.0720
0.0880
0.1000
0.9996
1.0000
1.0013
1.0021
1.0030
1.0036
2.328
2.331
2.339
2.344
2.349
2.353
Potassium nitrate
32.65
32.55
32.23
32.09
31.94
31.85
0.0344
0.0375
0.0415
0.0455
0.0480
0.0508
0.0240
0.0320
0.0560
0.0720
0.0880
0.1001
0.9997
2.330
43.32
1.0002
2.333
42.96
1.0016
2.342
42.30
1.0026
2.349
41.82
1.0036
2.358
41.56
1.0043
2.360
41.39
70 mass % of 2-methoxy ethanol + water
0.0394
0.0420
0.0480
0.0529
0.0580
0.0604
Lithium nitrate
0.0246
0.0328
0.0573
0.0737
0.0901
0.1024
0.9980
0.9984
0.9994
1.0000
1.0007
1.0012
2.972
2.976
2.986
2.993
3.000
3.006
Sodium nitrate
30.76
30.58
30.29
29.99
29.83
29.71
0.0350
0.0380
0.0428
0.0468
0.0500
0.0527
0.0241
0.0321
0.0562
0.0723
0.0883
0.1004
0.9984
0.9988
1.0000
1.0009
1.0018
1.0024
2.974
2.977
2.989
2.997
3.007
3.013
Potassium nitrate
33.81
33.57
33.08
32.89
32.69
32.53
0.0389
0.0404
0.0473
0.0520
0.0580
0.0611
0.0240
0.0320
0.0560
0.0720
0.0880
0.1000
0.9985
0.9989
1.0004
1.0014
1.0023
1.0031
44.37
43.98
42.96
42.48
42.13
41.92
0.0452
0.0469
0.0567
0.0623
0.0650
0.0780
2.977
2.981
2.996
3.005
3.013
3.029
Apparent Molar ……………… 2-Methoxy ethanol Solutions at T = 298.15 K
262
Table 3. Limiting Apparent Molar Volumes ( φV o ) and the Experimental Slopes ( SV* )
of Eq. 3 for Mineral salts along with the Standard Deviation ( σ ) in Different Molality
(m1) of 2-Methoxy ethanol (1) + Water (2) Solutions at 298.15 K
Solvent mixtures
φV o ⋅ 106
/m3 ⋅ mol−1
SV* .106
/(m9 ⋅ mol−3 )1/ 2
Lithium nitrate
σ
0 mass % of 2-methoxy ethanol
27.80 a
-
-
10 mass % of 2-methoxy ethanol
29.85
-2.96
0.0003
40 mass % of 2-methoxy ethanol
30.68
-4.58
0.0003
70 mass % of 2-methoxy ethanol
31.76
-6.40
0.0000
Sodium nitrate
0 mass % of 2-methoxy ethanol
28.22 b
-
-
10 mass % of 2-methoxy ethanol
32.58
-3.30
0.0002
40 mass % of 2-methoxy ethanol
33.43
-5.03
0.0000
70 mass % of 2-methoxy ethanol
34.99
-7.79
0.0000
Potassium nitrate
0 mass % of 2-methoxy ethanol
38.28 a
-
-
10 mass % of 2-methoxy ethanol
43.35
-7.71
0.0018
40 mass % of 2-methoxy ethanol
44.70
-11.58
0.0026
70 mass % of 2-methoxy ethanol
46.01
-15.09
0.0060
a Value
obtained from density data reported Ref 23.
b
Values taken from Ref 24.
Apparent Molar ……………… 2-Methoxy ethanol Solutions at T = 298.15 K
263
Table 4. Values of Viscosity A and B Coefficients derived from Eq.6 for Mineral salts
in Different Molality (m1) of 2-Methoxy ethanol (1) + Water (2) Solutions at 298.15
K
Solvent mixtures
B /L ⋅ mol−1
A /L1/2 ⋅ mol−1/2
Lithium nitrate
10 mass % of 2-methoxy ethanol
0.056
0.022
40 mass % of 2-methoxy ethanol
0.073
0.020
70 mass % of 2-methoxy ethanol
0.105
0.018
Sodium nitrate
10 mass % of 2-methoxy ethanol
0.073
0.021
40 mass % of 2-methoxy ethanol
0.097
0.019
70 mass % of 2-methoxy ethanol
0.139
0.016
Potassium nitrate
10 mass % of 2-methoxy ethanol
0.086
0.021
40 mass % of 2-methoxy ethanol
0.131
0.018
70 mass % of 2-methoxy ethanol
0.183
0.015
Apparent Molar ……………… 2-Methoxy ethanol Solutions at T = 298.15 K
264
Table 5. Partial molar volumes of transfer from water to different aqueous 2Methoxy ethanol solutions for NaNO3, KNO3 at 298.15 K.
Solvent mixtures
φV0 × 106 / m3 ⋅ mol−1
∆φV0 × 106 / m 3 ⋅ mol −1
Lithium nitrate
0 mass % of 2-methoxy ethanol
27.80 a
0.00
10 mass % of 2-methoxy ethanol
29.85
2.05
40 mass % of 2-methoxy ethanol
30.68
2.88
70 mass % of 2-methoxy ethanol
31.76
3.96
Sodium nitrate
0 mass % of 2-methoxy ethanol
28.22 b
0.00
10 mass % of 2-methoxy ethanol
32.58
4.36
40 mass % of 2-methoxy ethanol
33.43
5.21
70 mass % of 2-methoxy ethanol
34.98
6.76
Potassium nitrate
0 mass % of 2-methoxy ethanol
38.28 a
0.00
10 mass % of 2-methoxy ethanol
43.35
5.06
40 mass % of 2-methoxy ethanol
44.70
6.41
70 mass % of 2-methoxy ethanol
46.01
7.73
Apparent Molar ……………… 2-Methoxy ethanol Solutions at T = 298.15 K
265
Table-6: Values of (φV0,2 − φV0,1 ) , ∆µ10 ≠ , ∆µ 20≠ for mineral salts in aqueous 2-methoxy
ethanol solutions at 298.15 K.
Parameters
Lithium nitrate
Sodium nitrate
Potassium nitrate
10 mass % of 2-methoxy ethanol
(φV0,2 − φV0,1 ) ⋅106 / m3 ⋅ mol−1
-3.95
3.76
14.53
∆µ10≠ /( kJ ⋅ mol −1 )
11.02
11.02
11.02
∆µ 20≠ /( kJ ⋅ mol −1 )
15.50
17.67
19.63
40 mass % of 2-methoxy ethanol
(φV0,2 − φV0,1 ) ⋅106 / m3 ⋅ mol−1
-2.76
4.59
15.85
∆µ10≠ /( kJ ⋅ mol −1 )
12.69
12.69
12.69
∆µ 20≠ /( kJ ⋅ mol −1 )
18.69
21.48
25.31
70 mass % of 2-methoxy ethanol
(φV0,2 − φV0,1 ) ⋅106 / m3 ⋅ mol−1
-2.10
6.00
17.03
∆µ10≠ /( kJ ⋅ mol −1 )
13.31
13.31
13.31
∆µ 20≠ /( kJ ⋅ mol −1 )
22.14
25.71
30.42
Figures:
Figure 1: Plot of φV0 × 106 / m 3 ⋅ mol −1 of lithium nitrate as a function of mass percent
of 2-methoxy ethanol in different binary mixture of 2-methoxy ethanol + water at
298.15K
Apparent Molar ……………… 2-Methoxy ethanol Solutions at T = 298.15 K
266
Figure 2: Plot of φV0 × 106 / m 3 ⋅ mol −1 of Sodium nitrate as a function of mass percent
of 2-methoxy ethanol in different binary mixture of 2-methoxy ethanol + water at
298.15K
Figure 3: Plot of φV0 × 106 / m 3 ⋅ mol −1 of Potassium nitrate as a function of mass
percent of 2-methoxy ethanol in different binary mixture of 2-methoxy ethanol +
water at 298.15K
Apparent Molar ……………… 2-Methoxy ethanol Solutions at T = 298.15 K
267
Figure 4: Plot of SV* × 106 / ( m 9 ⋅ mol −3 )1/ 2 of lithium nitrate as a function of mass
percent of 2-methoxy ethanol in different binary mixture of 2-methoxy ethanol +
water at 298.15K
Figure 5: Plot of SV* × 106 / ( m 9 ⋅ mol −3 )1/ 2 of sodium nitrate as a function of mass
percent of 2-methoxy ethanol in different binary mixture of 2-methoxy ethanol +
water at 298.15K
Apparent Molar ……………… 2-Methoxy ethanol Solutions at T = 298.15 K
268
Figure 6: Plot of SV* × 106 / ( m 9 ⋅ mol −3 )1/ 2 of potassium nitrate as a function of
mass percent of 2-methoxy ethanol in different binary mixture of 2-methoxy
ethanol + water at 298.15K.
Figure 7: Plots of partial molar volumes of transfer ( ∆φV0 × 10 6 / m 3 ⋅ mol −1 ) from
water to different aqueous 2-methoxy ethanol solutions for lithium nitrate at
298.15K.
Apparent Molar ……………… 2-Methoxy ethanol Solutions at T = 298.15 K
269
Figure 8: Plots of partial molar volumes of transfer ( ∆φV0 × 10 6 / m 3 ⋅ mol −1 ) from
water to different aqueous 2-methoxy ethanol solutions for sodium nitrate at
298.15K.
Figure 9: Plots of partial molar volumes of transfer ( ∆φV0 × 106 / m 3 ⋅ mol −1 ) from
water to different aqueous 2-methoxy ethanol solutions for potassium nitrate at
298.15K.