study of volumetric and viscometric properties on non...

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CHAPTER – 5

Study of volumetric and viscometric properties on non aqueous – non electrolyte liquid mixtures

SECTION - A Binary liquid mixtures of propanoic acid with N,N-dimethyl aniline/N,N-diethyl aniline

SECTION - B Propanoic acid with equimolar mixture of (N,N-dimethyl formamide and methanol/ethanol/1-propanol)

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Introduction

The volumetric and viscometric study of non aqueous – non electrolyte liquid

mixtures enables the determination of some useful thermodynamic and other properties that

are highly sensitive to molecular interactions [1−4]. Knowledge of the temperature

dependence of excess properties of liquid mixtures provides valuable information on the

nature of inter molecular interactions existing among the component molecules [5–7]. The

volumetric and viscometric study of molecular interactions in some non aqueous – non

electrolyte liquid mixtures is presented in this chapter. These molecular interactions are studied

at three different temperatures (303.15, 313.15 and 323.15 K). This chapter is divided into two

sections namely, Section-A and Section-B.

Binary mixtures of Propanoic acid with N,N-dimethyl aniline and N,N-diethyl aniline

are presented in section-A. Thermodynamic properties of liquid acid-base mixtures were

studied by Rattan et al [8], Horacio N. Solimo et al [9] and Begona Garcia et al [10] with

propanoic acid as one component in binary mixtures. Katz et al [11] and Rama Murthy et al

[12-14] studied the volumetric and viscometric properties in binary liquid mixtures of aniline

and substituted anilines such as N-methyl aniline, N,N-dimethyl aniline, N-ethyl aniline,

N,N-diethyl aniline as one component and toluene or n-butanol or m-cresol or o- cresol as

other component. Ghasemi et al [15] reported the densities and viscosities for the binary and

ternary mixtures of 1,4-dioxane+1-hexanol+N,N-dimethylaniline.

Recently, Manukonda et al [16] studied the volumetric, speed of sound data and

viscosity at (303.15 and 308.15) K for the binary mixtures of N,N–diethyl aniline + aliphatic

ketones (C3-C5), + 4-methyl-2-pentanone. Gowrisankar et al [17] reported the volumetric,

speed of sound data and viscosity at (303.15 and 308.15) K for the binary mixtures of N,N-

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dimethyl aniline + aliphatic ketones (C3–C5), +4-methyl-2-pentanone, +acetophenone,

+cyclic ketones.

Study of volumetric and viscometric properties in propanoic acid with equimolar

mixture of N,N-dimethyl formamide + methanol/ethanol/1-propanol is depicted in section-B.

Previous literature shows that, Kharat and Nikam [18] studied the density and viscosity

studies of binary mixtures of aniline+benzene and ternary mixtures of (aniline+benzene +

N,N-dimethyl formamide) at 298.15, 303.15, 308.15, and 313.15 K. Intermolecular

interaction studies in organic ternary liquid mixtures benzene, chlorobenzene and

nitrobenzene with N,N-dimethyl formamide (DMF) in cyclohexane by ultrasonic velocity

measurements was studied by Thirumaran and Sudha [19]. Densities, excess molar volumes,

viscosity, and refractive indices studies of binary and ternary liquid mixtures of methanol (1)

+ ethanol (2) + 1,2-propanediol (3) at 81.5 kPa were carried out by Zarei et al [20].

In view of the industrial importance of liquid acid-base mixtures, in this chapter we

reported densities (ρ) viscosities (η) of the liquid mixtures and the properties such as

deviation in viscosity (Δη), excess Gibb’s free energy of activation of viscous flow (ΔG*E),

molar volume (Vm), excess molar volume ( EmV ), partial molar volumes ( 1,mV , 2,mV ), excess

partial molar volumes (EmV 1, ,

EmV 2, ), partial molar volumes at infinite dilution (

1,mV ,

2,mV ) and

excess partial molar volumes at infinite dilution ( ,1,

EmV , ,

2,EmV ). The variations of these

properties with composition as well as with temperature are discussed in terms of molecular

interactions existing among the molecules of these mixtures. Deviation/excess properties are

fitted to Redlich-Kister type polynomial equation. The experimental viscosity data of all

binary/equimolar liquid mixtures are correlated with the viscosity models such as Grunberg

and Nissan, Hind et al., Katti and Chaudhrai, and Heric and Brewer.

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Section A

Binary liquid mixtures of propanoic acid with

N,N-dimethyl aniline/N,N-diethyl aniline

5.A.1 Importance and properties of the chemicals

Propanoic acid (PA) is a naturally occurring carboxylic acid with chemical formula

CH3CH2COOH. It is a clear liquid with a pungent odor and it is used as food preservative

(calcium and sodium propionate). It is miscible with water. The melting and boiling points

are -210C and 1410C respectively. Propanoic acid inhibits the growth of mold and some

bacteria at the levels between 0.1 and 1% by weight. Hence, it is consumed as a preservative

for both animal feed and food for human consumption. It is also useful as an intermediate in

the production of other chemicals, especially polymers, plastics, cosmetics.

N,N-dimethyl aniline (DMA) is an organic chemical compound, a substituted

derivative of aniline with chemical formula C6H5N(CH3)2. It consists of a tertiary amine,

featuring dimethyl amino group attached to a phenyl group. This oily liquid is colourless

when pure, but commercial samples are often yellow. The melting and boiling points are 20C

and 1940C respectively. DMA is a key precursor to commercially important triaryl methane

dyes such as malachite green and crystal violet. It serves as a promoter in the curing of

polyester and vinyl ester resins.

N,N-diethyl aniline (DEA) is a chemical compound with the molecular formula

(C2H5)2NC6H5 . The melting and boiling points are -380C and 2160C respectively. It is used

as an intermediate in the manufacture of dyes, pharmaceuticals and other chemicals, and also

as a reaction catalyst. In organic synthesis, the complex diethyl aniline borane (DEANB) is

used as a reducing agent. Diethyl aniline may be genotoxic because it has been found to

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increase the rate of sister chromatid exchange. These, aromatic anilines, N,N-dimethyl

aniline, N,N-diethyl aniline are used as intermediates to manufacture dyes, vanillin, and as a

stabilizer for calorimetric peroxidase determination.

5.A.2 Experimental

High purity and Analytical Reagent (AR) grade compounds of propanoic acid, N,N-

dimethyl aniline and N,N-diethyl aniline obtained from LOBA chemicals, India are used in

the present study. All the chemicals are further purified by standard methods [21,22],

distillation, fractional distillation under reduced pressure and only middle fractions were

collected. Finally, after purification method the purity of the propanoic acid, N,N-dimethyl

aniline and N,N-diethyl aniline is found to be w = 0.997, w = 0.993 and w = 0.993

respectively. Before use, the chemicals were stored over 0.4 nm molecular sieves

approximately for 72 hr to remove water content and degassed.

Binary mixtures of propanoic acid with N,N-dimethyl aniline and N,N-diethyl aniline

(PA+DMA and PA+DEA) are prepared by mass in air tight bottles over the entire

composition range of propanoic acid (i.e 0 to 100% of PA). The mass measurements are

performed on a METTLER TOLEDO (Switzerland make) ABB5- S/FACT digital balance

with an accuracy ±0.01mg. The uncertainty in the mole fraction is 10-4. Densities of pure

liquids and their mixtures have been determined by using a 5 cm3 two stem double-walled

Parker & Parker type pyknometer [23].This pyknometer is calibrated with triply distilled

water.

An Ostwald viscometer has been used to determine the viscosity of the liquid

mixture, which is calibrated as described by Subramanyam Naidu and Ravindra Prasad [24]

using triply distilled water. The viscometer was also calibrated using benzene, CCl4 liquids

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etc at working temperatures. The length of one of the capillary tube of viscometers used in

the present study is 8 cm and its diameter is 0.56 mm. The reproducibility in the measured

parameters density and viscosity are 3 in 105 parts and ± 0.2% respectively.

The experiment is performed at three different temperatures 303.15, 313.15 and

323.15 K. The densities and viscosities measured at 303.15 K and 313.15 K for the pure

liquids used in this investigation are compiled in Table 5.A.1 together with the literature data

[8,11,13] available. These results are in good agreement with the reported data.

5.A.3 Results and discussion

The experimental values of densities (ρ) and viscosities (η) are reported in Tables

5.A.2 and 5.A.3 for DMA+PA and DEA+PA binary mixtures respectively. It has been

observed that the density varies almost linearly with the concentration of propanoic acid as

well as with temperature but the viscosity changes non-linearly showing maxima in all the

systems studied at all temperatures investigated. This type of behaviour could be attributed

to complex formation.

The experimental values of density and viscosity are used to calculate the

deviation/excess properties such as deviation in viscosity, Δη, excess molar volume, EVm and

excess Gibbs free energy of activation of viscous flow, ΔG*E. The deviation/excess

properties are illustrated in Table 5.A.4. The variation of deviation in viscosity with mole

fraction of propanoic acid as shown in Figures 5.A.1 and 5.A.2. Generally, negative values

of Δη indicate the presence of dispersion forces or mutual loss of specific interactions in like

molecules operating in the systems arising due to weak intermolecular interactions and

positive values of deviation in viscosity indicate strong specific interactions [25,26]. The

sign and magnitude of Δη depend on the combined effect of factors such as molecular size,

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shape, and intermolecular forces. In general ethyl groups are more +I effect than methyl

groups. In DEA the ethyl groups are more electron releasing than methyl groups of DMA on

nitrogen atom. So, the nitrogen in DEA possesses more electron density than in DMA,

therefore DEA is more favoured to accept the proton of the PA. Hence it is an appropriate

reason to support the observed more positive Δη values in propanoic acid + N,N-diethyl

aniline system.

Table 5.A.1 Comparison of densities (ρ) and viscosities (η) of pure liquids with literature data at 303.15 and 313.15 K Component temp. T/K ρ/kg·m-3 η/10-3N·s·m-2

present work literature present work literature Propanoic acid 303.15 982.1 982.0 [8] 0.950 0.9498[8]

313.15 973.4 971.0 [8] 0.848 0.8453[8]

N,N-dimethyl aniline 303.15 948.0 948.0 [13] 1.174 1.173 [11]

313.15 938.5 939.75 [11] 0.982 0.985 [11]

N,N-diethyl aniline 303.15 926.0 925.9 [13] 1.703 1.709 [13]

313.15 917.7 918.0 [13] 1.402 1.402 [13]

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Table 5.A.2 Experimental values of densities (ρ) and viscosities (η) with mole fraction of propanoic acid, x for N,N-dimethyl aniline + Propanoic acid binary system at 303.15, 313.15 and 323.15 K x T = 303.15 K T = 313.15 K T = 323.15 K

ρ/kg·m-3 η/10-3N·s·m-2 ρ/kg·m-3 η/10-3N·s·m-2 ρ/kg·m-3 η/10-3N·s·m-2

0.0000 948.0 1.174 938.5 0.982 930.7 0.826

0.1020 954.4 1.270 943.7 1.019 934.8 0.843

0.2054 959.8 1.329 949.1 1.058 939.7 0.869

0.3071 964.5 1.386 954.2 1.093 944.5 0.895

0.4092 969.3 1.446 959.2 1.124 949.1 0.920

0.5107 974.0 1.494 964.0 1.149 953.5 0.940

0.6178 978.6 1.545 968.6 1.151 958.0 0.944

0.7083 982.2 1.534 972.2 1.119 961.1 0.912

0.8023 985.3 1.457 975.3 1.060 963.5 0.864

0.8987 986.4 1.225 975.7 0.965 963.5 0.778

1.0000 982.1 0.950 973.4 0.848 961.4 0.706

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Table 5.A.3 Experimental values of densities (ρ) and viscosities (η) with mole fraction of propanoic acid, x for N,N-diethyl aniline + Propanoic acid binary system at 303.15, 313.15 and 323.15 K x T = 303.15 K T = 313.15 K T = 323.15 K


0.0000 926.0 1.703 917.7 1.402 912.8 1.049

0.1047 933.4 1.801 924.6 1.450 919.5 1.068

0.2096 942.1 2.040 932.8 1.590 926.4 1.173

0.3142 952.1 2.404 942.2 1.765 934.9 1.315

0.4164 963.8 2.910 953.7 2.118 944.3 1.555

0.5177 977.9 3.663 967.3 2.527 955.3 1.865

0.6097 989.1 4.040 977.5 2.880 965.3 2.100

0.7077 996.2 3.968 984.0 2.738 971.3 1.949

0.8123 995.0 3.260 982.7 2.086 974.7 1.510

0.9156 990.9 1.532 980.1 1.247 974.2 0.972

1.0000 982.1 0.950 973.4 0.848 961.4 0.706

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Table 5.A.4 Calculated values of deviation in viscosities, Δη, excess molar volumes, EmV

and excess Gibbs free energy, ΔG*E with mole fraction of propanoic acid, x for all binary system at 303.15, 313.15 and 323.15 K N,N-dimethyl aniline+propanoic acid N,N-diethyl aniline+propanoic acid

x EmV / Δη/ ΔG*E/ x E

mV / Δη/ ΔG*E/ 10-6m3.mol-1 10-3N·s·m-2 kJ.mol-1 10-6m3.mol-1 10-3N·s·m-2 kJ.mol-1

T =303.15 K 0.0000 0.00 0.000 0.00 0.0000 0.00 0.000 0.00 0.1020 -0.55 0.1190 268.79 0.1047 -0.73 0.177 338.96 0.2054 -0.89 0.201 454.02 0.2096 -1.51 0.495 840.03 0.3071 -1.10 0.281 626.40 0.3142 -2.29 0.938 1428.44 0.4092 -1.25 0.364 794.98 0.4164 -3.10 1.521 2065.96 0.5107 -1.35 0.434 933.08 0.5177 -3.96 2.350 2784.62 0.6178 -1.36 0.510 1071.60 0.6097 -4.34 2.796 3150.72 0.7083 -1.31 0.519 1092.57 0.7077 -4.07 2.798 3233.22 0.8023 -1.16 0.463 1000.37 0.8123 -2.89 2.169 2879.75 0.8987 -0.80 0.253 599.88 0.9156 -1.51 0.519 1103.60 1.0000 0.00 0.000 0.00 1.0000 0.00 0.000 0.00 T =313.15 K 0.0000 0.00 0.000 0.00 0.0000 0.00 0.000 0.00 0.1020 -0.40 0.050 154.36 0.1047 -0.67 0.106 271.21 0.2054 -0.75 0.103 308.96 0.2096 -1.39 0.304 683.59 0.3071 -1.00 0.152 444.26 0.3142 -2.11 0.537 1115.45 0.4092 -1.19 0.197 563.42 0.4164 -2.93 0.947 1730.10 0.5107 -1.29 0.236 661.49 0.5177 -3.77 1.412 2312.60 0.6178 -1.30 0.252 703.33 0.6097 -4.08 1.816 2759.00 0.7083 -1.24 0.232 656.09 0.7077 -3.78 1.728 2739.68 0.8023 -1.09 0.186 537.39 0.8123 -2.60 1.135 2157.44 0.8987 -0.66 0.103 314.66 0.9156 -1.35 0.353 923.99 1.0000 0.00 0.000 0.00 1.0000 0.00 0.000 0.00 T =323.15 K 0.0000 0.00 0.000 0.00 0.0000 0.00 0.000 0.00 0.1020 -0.29 0.030 121.77 0.1047 -0.70 0.055 206.00 0.2054 -0.63 0.068 264.12 0.2096 -1.29 0.196 608.00 0.3071 -0.90 0.106 396.53 0.3142 -1.97 0.374 1049.00 0.4092 -1.09 0.143 519.66 0.4164 -2.61 0.649 1618.00 0.5107 -1.20 0.175 622.05 0.5177 -3.25 0.994 2209.72 0.6178 -1.24 0.192 675.08 0.6097 -3.67 1.260 2609.58 0.7083 -1.19 0.171 611.59 0.7077 -3.43 1.143 2496.83 0.8023 -1.01 0.134 492.24 0.8123 -2.80 0.740 1894.46 0.8987 -0.60 0.060 237.53 0.9156 -1.80 0.237 784.00 1.0000 0.00 0.000 0.00 1.0000 0.00 0.000 0.00

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The variations of excess molar volume, EmV with mole fraction of propanoic acid at

all temperatures for the binary systems are shown in Figures 5.A.3 and 5.A.4. The deviation

of a physical and chemical property of the liquid mixture from the ideal behaviour is a

measure of the interaction between molecules of the components of liquid mixtures and such

type of deviation is generally attributed to dipole-dipole interactions and hydrogen bond

between unlike molecules [27] respectively. The factors that are mainly responsible for the

expansion of volume i.e. positive values of EVm are: (i) breaking one or both of the

components in a solution i.e. loss of dipolar association between the molecules (dispersion

forces). (ii) The geometry of molecular structures which does not favour the fitting of

molecules of one component into the voids created by the molecules of other component.

(iii) Steric hindrance of the molecules. The negative values of EVm are due to strong specific

interactions such as (iv) association of molecules through the formation of hydrogen bond

(or) association due to dipole-dipole interactions (or) association due to induced dipole -

dipole interactions (v) accommodation of molecules due to larger differences in molar

volumes.

The variation of excess molar volume in the present investigation is negative over the

entire mole fraction range. Both the components of the liquid mixtures studied are polar

molecules in nature. The observed negative EVm values are due to the interaction between

the proton of acid and lone pair of electrons on the nitrogen atom of aniline/resonant electron

density on benzene ring of substituted aniline. Due to the large difference in molar

volumes/masses of propanoic acid and substituted anilines accommodation of smaller

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molecules of one component into the voids created by the other component of molecules is

also responsible for observed negative EVm values. The above factors are responsible for the

negative values of EVm [28].

From the figures 5.A.3 and 5.A.4 it has been observed that as the temperature of the

systems increases the negative excess molar volumes decrease indicating the decrease of

interaction between the unlike molecules. The negative excess molar volumes follows the

order N,N-diethyl aniline > N,N-dimethyl aniline hence the strength of interactions as

follows, N,N-diethyl aniline > N,N-dimethyl aniline. The variations of excess Gibbs free

energy with mole fraction of propanoic acid at all temperatures for the binary systems are

shown in Figures 5.A.5 and 5.A.6. The ΔG*E are found to be positive for both the systems

and at all temperatures. These positive values are indicating the existing of strong

interactions between the components of unlike molecules. As temperature increases these

positive values are found to decrease which shows the decrease of interaction between

constituent molecules.

The values of deviation in viscosity and excess molar volume have been fitted to

Redlich-Kister type polynomial [29] equation. The R-K coefficients and the standard

deviations of both binary mixtures have been presented in Table 5.A.5. The smaller standard

deviation values show that the polynomial better fits the calculated properties.

The partial molar volumes ,1mV of component 1(PA) and ,2mV of component 2

(DMA/DEA) in the mixtures over the entire composition range are calculated. These values

are furnished in Table 5.A.6. From this table, the values of ,1mV and ,2mV for both the

components in the mixtures are lesser than their respective molar volumes in the pure state

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Table 5.A.5 Coefficients Ai of Redlich-Kister type polynomial equation (3.28) and the corresponding standard deviations, σ (3.29) of all the systems under investigation property A0 A1 A2 A3 A4 σ N,N-dimethyl aniline+propanoic acid

T = 303.15 K

Δη /10-3N·s·m-2 1.715 -1.650 1.467 0.987 -1.474 0.009

EVm /10-6m3·mol-1 0.01 -6.91 16.25 -21.59 12.24 0.02

T = 313.15 K

Δη /10-3N·s·m-2 0.928 -0.584 -0.036 0.352 -0.149 0.002

EVm /10-6m3·mol-1 0.01 -4.82 6.89 -7.52 5.45 0.02

T = 323.15 K

Δη /10-3N·s·m-2 0.689 -0.524 -0.061 0.485 -0.376 0.003

EVm /10-6m3·mol-1 0.01 -3.41 1.53 -0.21 2.08 0.02

N,N-diethyl aniline+propanoic acid

T = 303.15 K

Δη /10-3N·s·m-2 8.601 -14.681 5.040 15.866 -15.955 0.074

EVm /10-6m3·mol-1 -0.09 -1.75 -31.27 45.85 -12.65 0.19

T = 313.15 K

Δη /10-3N·s·m-2 5.460 -9.244 0.247 10.985 -6.042 0.041

EVm /10-6m3·mol-1 -0.09 -0.056 -35.45 53.48 -17.29 0.19

T = 323.15 K

Δη /10-3N·s·m-2 3.830 -6.168 -1.079 7.310 -2.734 0.037

EVm /10-6m3·mol-1 -0.03 -4.97 -6.10 3.33 7.74 0.12

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Table 5.A.6 Calculated values of partial molar volumes ( m,1V and m,2V ) with mole fraction of propanoic acid, x for all binary system at 303.15, 313.15 and 323.15 K N,N-dimethyl aniline+propanoic acid N,N-diethyl aniline+propanoic acid x m,1V / m,2V / x m,1V / m,2V / 10-6m3.mol-1 10-6m3.mol-1 10-6m3.mol-1 10-6m3.mol-

T =303.15 K

0.0000 74.71 127.84 0.0000 74.38 161.17 0.1020 75.02 127.82 0.1047 74.82 161.15 0.2054 75.14 127.80 0.2096 74.74 161.18 0.3071 75.19 127.77 0.3142 74.60 161.23 0.4092 75.24 127.75 0.4164 74.60 161.24 0.5107 75.27 127.72 0.5177 74.75 161.10 0.6178 75.30 127.68 0.6097 74.97 160.81 0.7083 75.33 127.64 0.7077 75.20 160.32 0.8023 75.36 127.57 0.8123 75.38 159.72 0.8987 75.40 127.39 0.9156 75.43 159.25 1.0000 75.43 126.89 1.0000 75.43 159.21

T =313.15 K 0.0000 75.72 129.13 0.0000 75.06 162.62 0.1020 75.72 129.13 0.1047 75.57 162.60 0.2054 75.79 129.12 0.2096 75.46 162.63 0.3071 75.86 129.09 0.3142 75.30 162.70 0.4092 75.91 129.06 0.4164 75.30 162.71 0.5107 75.94 129.03 0.5177 75.47 162.56 0.6178 75.98 128.99 0.6097 75.69 162.26 0.7083 76.02 128.93 0.7077 75.92 161.77 0.8023 76.06 128.83 0.8123 76.06 161.19 0.8987 76.09 128.69 0.9156 76.11 160.74 1.0000 76.10 128.51 1.0000 76.10 160.61

T =323.15 K 0.0000 76.87 130.21 0.0000 75.90 163.50 0.1020 76.72 130.22 0.1047 76.56 163.47 0.2054 76.75 130.21 0.2096 76.49 163.49 0.3071 76.81 130.18 0.3142 76.36 163.54 0.4092 76.86 130.15 0.4164 76.38 163.54 0.5107 76.90 130.12 0.5177 76.51 163.42 0.6178 76.93 130.08 0.6097 76.66 163.21 0.7083 76.97 130.01 0.7077 76.80 162.92 0.8023 77.01 129.91 0.8123 76.91 162.51 0.8987 77.05 129.78 0.9156 77.01 161.77 1.0000 77.06 129.70 1.0000 77.06 160.51

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i.e contraction of volume takes place on mixing PA with DMA/DEA. Figures 5.A.7 and

5.A.8 represent the variation of excess partial molar volumes of PA and DMA/DEA in the

binary mixtures of PA+DMA and PA+DEA respectively. Examination of these figures

reveals that, indicating strong interactions exist between the unlike molecules. These figures

support the conclusions drawn from EmV values.

The dynamic viscosities of the binary liquid mixtures have been calculated using

various empirical relations like Grunberg and Nissan [30], Hind and Ubbelohde [31], Katti

and Chaudari [32], Heric and Brewer [33] and the corresponding interaction parameters are

also evaluated. Theoretical values of viscosity of the binary liquid mixtures of PA+DMA

and PA+DEA calculated using the above equations are given in Tables 5.A.7 and 5.A.8

respectively at all three temperatures. Table 5.A.9 presents the values of interaction

parameters along with the standard deviations, σ. The variation of these interaction

parameters with temperature or composition follows the order N,N-diethyl aniline > N,N-

dimethyl aniline at constant composition and temperature respectively. Further the

interaction parameter values are found to decrease with an increase of temperature for all the

systems studied. These results are in good agreement with the results derived from the

excess properties. Prolongo et al [34] reported positive values of interaction parameter

corresponding to systems with negative excess molar volumes. This is in good agreement

with our results. The estimated values of σ are smaller indicating that experimental values of

viscosities are well correlated by all the viscosity models.

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Table 5.A.7 Theoretical values of viscosities from eqn.s [(3.47) - (3.53)] with mole fraction of propanoic acid, x for N,N-dimethyl aniline+propanoic acid at 303.15, 313.15 and 323.15 K

Grunberg Hind Katti Heric x & & & &

Nissan Ubbelohde Chaudari Brewer T = 303.15 K

0.0000 1.174 1.174 1.174 1.174 0.1020 1.333 1.329 1.333 1.334 0.2054 1.464 1.444 1.463 1.467 0.3071 1.552 1.517 1.550 1.555 0.4092 1.592 1.550 1.588 1.594 0.5107 1.578 1.543 1.575 1.579 0.6178 1.509 1.493 1.506 1.508 0.7083 1.411 1.415 1.411 1.409 0.8023 1.280 1.301 1.282 1.278 0.8987 1.124 1.149 1.127 1.122 1.0000 0.950 0.950 0.950 0.950

T = 313.15 K 0.0000 0.982 0.982 0.982 0.982 0.1020 1.053 1.052 1.053 1.055 0.2054 1.108 1.103 1.108 1.111 0.3071 1.143 1.135 1.142 1.145 0.4092 1.157 1.147 1.155 1.158 0.5107 1.148 1.141 1.147 1.148 0.6178 1.116 1.114 1.115 1.115 0.7083 1.071 1.075 1.072 1.070 0.8023 1.011 1.019 1.012 1.009 0.8987 0.936 0.944 0.937 0.935 1.0000 0.848 0.848 0.848 0.848

T = 323.15 K 0.0000 0.826 0.826 0.826 0.826 0.1020 0.873 0.871 0.873 0.874 0.2054 0.908 0.904 0.908 0.910 0.3071 0.929 0.923 0.929 0.931 0.4092 0.936 0.929 0.935 0.937 0.5107 0.927 0.922 0.926 0.927 0.6178 0.902 0.900 0.901 0.901 0.7083 0.869 0.871 0.869 0.867 0.8023 0.824 0.830 0.826 0.823 0.8987 0.770 0.776 0.771 0.769 1.0000 0.706 0.706 0.706 0.706

222

Table 5.A.8 Theoretical values of viscosities from eqn.s [(3.47)-(3.53)] with mole fraction of propanoic acid, x for N,N-diethyl aniline+propanoic acid at 303.15, 313.15 and 323.15 K



0.0000 1.703 1.703 1.703 1.703 0.1047 2.359 2.365 2.351 2.368 0.2096 2.986 2.855 2.969 3.002 0.3142 3.450 3.170 3.428 3.467 0.4164 3.641 3.311 3.625 3.653 0.5177 3.528 3.287 3.530 3.531 0.6097 3.185 3.125 3.202 3.180 0.7077 2.646 2.806 2.665 2.635 0.8123 1.988 2.297 1.996 1.978 0.9156 1.372 1.624 1.376 1.367 1.0000 0.950 0.950 0.950 0.950

T = 313.15 K

0.0000 1.402 1.402 1.402 1.402 0.1047 1.801 1.791 1.796 1.808 0.2096 2.155 2.076 2.146 2.167 0.3142 2.402 2.256 2.390 2.414 0.4164 2.494 2.330 2.486 2.502 0.5177 2.422 2.306 2.426 2.424 0.6097 2.226 2.199 2.238 2.222 0.7077 1.916 1.996 1.929 1.908 0.8123 1.525 1.679 1.528 1.517 0.9156 1.135 1.263 1.137 1.131 1.0000 0.848 0.848 0.848 0.848

T = 323.15 K

0.0000 1.049 1.049 1.049 1.049 0.1047 1.310 1.313 1.307 1.315 0.2096 1.539 1.508 1.531 1.548 0.3142 1.699 1.632 1.688 1.708 0.4164 1.763 1.685 1.753 1.769 0.5177 1.726 1.672 1.721 1.728 0.6097 1.611 1.603 1.612 1.608 0.7077 1.419 1.469 1.423 1.414 0.8123 1.169 1.259 1.174 1.162 0.9156 0.908 0.983 0.914 0.904 1.0000 0.706 0.706 0.706 0.706

223

Table 5.A.9 various interaction parameters calculated from eqns. [(3.47)-(3.53)] and the corresponding standard deviations (σ/10-3 N.s.m-2)

T/K G12 σ H12 σ Wvis/RT σ Δ12 σ

N,N-dimethyl aniline+propanoic acid

303.15 1.617 0.150 0.002 0.125 1.693 0.149 1.739 0.153

313.15 0.926 0.049 0.001 0.043 1.009 0.048 1.047 0.050

323.15 0.781 0.040 0.001 0.037 0.868 0.039 0.902 0.041

N,N-diethyl aniline+propanoic acid

303.15 4.128 1.078 0.005 0.913 4.277 1.062 4.373 1.091

313.15 3.232 0.636 0.003 0.558 3.394 0.626 3.478 0.645

323.15 2.816 0.417 0.002 0.380 2.972 0.411 3.062 0.424

224

Conclusions

(i) Densities and viscosities of binary mixtures of propanoic acid with N,N-dimethyl

aniline and N,N-diethyl aniline are measured over the entire composition range at

T=(303.15, 313.15, and 323.15) K.

(ii) The deviations in viscosity, excess molar volumes are computed from the

experimental results. These deviation/excess properties have been fitted to Redlich-

Kister type polynomial.

(iii) These results indicate the presence of strong specific interactions such as interactions

between proton of propanoic acid and lone pair of electrons on the nitrogen atom of

aniline and due to the observed difference in molar volumes of propanoic acid and

substituted aniline is responsible for the observed negative EVm and positive Δη

values in the present investigated systems.

(iv) The strength of interactions follows the order N,N-diethyl aniline + propanoic acid >

N,N-dimethyl aniline + propanoic acid. The strength of interactions is also studied

with the variation of temperature.

(v) The experimental viscosity values are compared with the viscosity values obtained

from different empirical relations and these are in good agreement with the

experimental values.

225

Section B

Propionic acid with equimolar mixture of

(N,N-dimethyl formamide and methanol/ethanol/1-propanol)

5.B.1 Importance and properties of the chemicals

Alkanols are of interesting simple examples of biological and industrial important

amphiphilic materials [35]. Alkanol are polar molecules and self associated through

hydrogen bonding of their hydroxyl groups [2]. Methanol also known as methyl alcohol or

wood alcohol with chemical formula CH3OH. The melting and boiling points are -970C and

64.70C respectively. It is the simplest alcohol, and is a light, volatile, colourless, flammable

liquid with a distinctive odor very similar to, but slightly sweeter than, that of ethanol

(drinking alcohol). At room temperature, it is a polar liquid, and is used as an antifreeze,

solvent, fuel, and as a denaturant for ethanol. Methanol is used on a limited basis to fuel

internal combustion engines.

Ethanol, also called ethyl alcohol, pure alcohol, grain alcohol, or drinking alcohol

with the structural formula CH3CH2OH. It is a volatile, color less liquid that has a slight

odor. The melting and boiling points are -1140C and 78.370C respectively. Ethanol is

miscible with water and is a good general purpose solvent. The largest single use of ethanol

is as a motor fuel and fuel additive Ethanol is the principal psychoactive constituent in

alcoholic beverages. It is found in paints, tinctures, markers, and personal care products such

as perfumes and deodorants.

1-Propanol or propan-1-ol or 1-propyl alcohol or n-propyl alcohol or n-propanol or

simply propanol is a primary alcohol with the formula CH3CH2CH2OH. It is a colourless

liquid having melting and boiling points are -1260C and 97 to 980C respectively. It is formed

226

naturally in small amounts during many fermentation processes and used as a solvent in the

pharmaceutical industry mainly for resins and cellulose esters. The dipole moments of

methanol, ethanol and 1-propanol are 1.70 D, 1.69 D and 1.58 D respectively. N,N-dimethyl

formamide has large dipole moment 3.82 D [36] and in view of this dipole-dipole

interactions are expected to play significant role to study the molecular interactions present

in the liquid mixtures. The properties of propanoic acid and N,N-dimethyl formamide are

discussed in earlier.

In the present investigation, we reported densities (ρ) and viscosities (η) of the liquid

mixtures of propanoic acid with equimolar mixture of N,N-dimethyl formamide and

methanol/ethanol/1-propanol at three different temperatures T = 303.15, 313.15 and 323.15

K over the entire mole fraction range of propanoic acid. The excess and deviation properties

such as excess molar volume ( EVm ), deviation in viscosity (Δη) and excess Gibb’s free

energy of activation of viscous flow (ΔG*E) have been calculated using experimental data of

ρ and η. The variation of EVm , Δη and ΔG*E with composition and temperature have been

discussed in terms of molecular interactions existing among the molecules of these mixtures.

5.B.2 Experimental

Propanoic acid (PA), N,N-dimethyl formamide (DMF), methanol (MOH), ethanol

(EOH) and 1-propanol (POH) used in the present study were the AR grade products from

LOBA Chemicals, India and were purified by standard methods described in the literature

[21,22] The mass fraction purity of liquids obtained is > 0.995. Before use, the chemicals

were stored over 0.4 nm molecular sieves approximately for 72 h to remove water content

and degassed.

227

Mixtures are prepared by mass in air tight bottles. The mass measurements are

performed with a METTLER TOLEDO (Switzerland make) ABB5-S/FACT digital balance

with an accuracy ± 0.01 mg. Densities and viscosities of pure liquids and liquid mixtures

have been determined using 5 cm3 two stem double walled Parker & Parker type pyknometer

[23] and Ostwald viscometer which is calibrated as described by Subrahmanyam Naidu and

Ravindra Prasad [24] using triply distilled water respectively. The reproducibility in the

measured parameters density and viscosity are 3 in 105 parts and ± 0.2% respectively. The

densities and viscosities of pure liquids in this investigation at three different temperatures

303.15, 313.15, and 323.15 are compiled in Table 5.B.1 together with the literature data

[8,18,22,37-45] available. These results are found to be in good agreement with literature

data.

5.B.3 Results and discussion

The experimental values of ρ and η are reported in Tables 5.B.2, 5.B.3 and 5.B.4

respectively for (DMF+MOH)+PA, (DMF+EOH)+PA and (DMF+POH)+PA mixtures at

different temperatures over the entire mole fraction, x of PA. It has been observed that the

density varies monotonically with the concentration of propanoic acid at all temperatures but

the viscosity changes non-linearly showing maxima at about x ≈ 0.6 in the PA rich region as

all investigated temperatures in all the systems. The observed maxima (peak) have found to

increase with increasing chain length of alcohols. Such deviations may be attributed to

specific interactions arising from the formation of complexes among the mixing molecules.

This type of behaviour could be attributed to complex formation.

The variation of EmV for all the systems at different temperatures is shown in Figures

5.B.1, 5.B.2 and 5.B.3. The variation of excess molar volume in the present investigation is

228

Table 5.B.1 Comparison of experimental values of density (ρ) and viscosity (η) of pure liquids with literature values Liquid ρ/kg.m-3 η/10-3N.s.m-2

present work literature present work literature T = 303.15 K Methanol 781.6 781.70[8] 0.513 0.5143[8] 781.96[22] 0.515 [22] Ethanol 779.9 780.66 [8] 0.980 0.987 [8] 780.68 [22] 1-Propanol 795.1 795.65 [8] 1.716 1.725[22] 795.48 [22] 1.705[22] N,N-dimethyl

formamide 939.9 939.8 [37] 0.768 0.756[37] 939.7 [18] 0.752 [38] Propanoic acid 982.1 982.0 [39] 0.950 0.9498 [39] T = 313.15 K Methanol 772.9 772.36 [8] 0.446 0.448 [8] 772.21[22] 0.452 [22] Ethanol 771.1 772.12[8] 0.812 0.823 [8] 772.13 [22] 0.814 [22] 1-Propanol 787.1 788.69 [8] 1.315 1.314 [8] 787.37 [22] 1.336 [22] N,N-dimethyl

formamide 932.1 930.2 [37] 0.678 0.673 [37] 929.8 [40] 0.664 [38] Propanoic acid 973.4 971.0[39] 0.848 0.8453[39] T = 323.15 K Methanol 764.8 762.7 [41] 0.405 0.395 [41] Ethanol 766.4 766.1 [41] 0.741 0.7493 [41] 1-Propanol 778.7 779.5 [42] 0.999 1.1004 [42] 1.1208 [43] N,N-dimethyl

formamide 921.6 920.1 [41] 0.593 0.614 [41] 921.14 [44] 0.6128 [45] Propanoic acid 961.4 959.5 [39] 0.706 0.8102 [39]

229

Table 5.B.2 Experimental values of densities (ρ) and viscosities (η) with mole fraction of PA, x for

(DMF+MOH)+PA binary system at 303.15, 313.15 and 323.15 K x T = 303.15 K T = 313.15 K T = 323.15 K


0.0000 892.2 0.674 882.8 0.580 878.3 0.503

0.1142 906.3 0.758 895.9 0.653 887.0 0.550

0.2189 919.3 0.868 908.2 0.729 898.4 0.610

0.324 931.5 1.001 920.4 0.837 911.4 0.696

0.4218 942.2 1.130 931.0 0.940 922.0 0.778

0.5248 952.7 1.267 942.1 1.041 932.4 0.875

0.6225 961.5 1.341 951.6 1.120 940.9 0.919

0.7209 969.4 1.341 960.0 1.115 948.6 0.925

0.8156 976.1 1.273 966.8 1.060 955.0 0.869

0.9074 980.1 1.098 971.1 0.950 958.9 0.767

1.0000 982.1 0.950 973.4 0.848 961.4 0.706

230

Table 5.B.3 Experimental values of densities (ρ) and viscosities (η) with mole fraction of PA, x for (DMF+EOH)+PA binary system at 303.15, 313.15 and 323.15 K x T = 303.15 K T = 303.15 K T = 303.15 K


0.0000 871.20 0.758 866.59 0.649 857.24 0.563

0.1110 887.16 0.856 880.21 0.720 870.10 0.619

0.2185 901.60 0.978 894.76 0.836 883.96 0.707

0.3265 915.62 1.118 908.53 0.940 897.19 0.789

0.4235 928.00 1.244 920.25 1.031 908.59 0.858

0.5197 939.77 1.352 931.51 1.119 919.66 0.931

0.6276 952.56 1.391 943.97 1.169 931.45 0.973

0.7309 964.47 1.387 955.56 1.151 942.23 0.963

0.8216 972.70 1.316 963.20 1.080 950.26 0.902

0.9121 978.37 1.132 969.46 0.964 957.02 0.789

1.0000 982.09 0.950 973.40 0.848 961.39 0.706

231

Table 5.B.4 Experimental values of densities (ρ) and viscosities (η) with mole fraction of PA, x for (DMF+POH)+PA binary system at 303.15, 313.15 and 323.15 K x T = 303.15 K T = 313.15 K T = 313.15 K


0.0000 869.77 0.893 860.55 0.764 850.95 0.655

0.1109 884.95 1.002 875.08 0.865 864.89 0.738

0.2178 899.49 1.099 889.57 0.958 878.78 0.803

0.3264 913.75 1.226 904.16 1.047 893.17 0.884

0.4283 926.75 1.339 916.96 1.136 905.76 0.953

0.5306 939.44 1.447 929.68 1.203 918.23 1.020

0.6279 950.77 1.472 940.96 1.232 929.19 1.032

0.7279 961.55 1.452 951.98 1.195 939.90 1.005

0.8185 970.66 1.375 960.80 1.120 948.62 0.946

0.9097 977.83 1.187 967.82 1.005 955.19 0.840

1.0000 982.09 0.950 973.40 0.848 961.39 0.706

235

negative over the entire mole fraction range [30]. The variation of Δη for all the

systems at different temperatures is shown in Figures 5.B.4, 5.B.5 and 5.B.6. The

variation of ΔG*E for all the systems at different temperatures is shown in Figures

5.B.7, 5.B.8 and 5.B.9. The observed negative EVm and positive Δη and ΔG*E values

reveal that strong interactions exist in the unlike molecules of the mixtures.

The factors that are mainly responsible for the expansion of molar volume i.e.

positive values of EVm are: (i) Breaking one or both of the components in a solution

i.e. loss of dipolar association between the molecules (dispersion forces). (ii) The

geometry of molecular structures which does not favour the fitting of molecules of

one component into the voids created by the molecules of other component. (iii)

Steric hindrance of the molecules. The negative values of EVm are due to strong

specific interactions such as (iv) association of molecules through the formation of

hydrogen bond (or) association due to dipole-dipole interactions (v) accommodation

of molecules due to considerable differences in molar volumes. The presence of

strong interaction is due to the hydrogen bonding (O…..H-O-) between carbonyl

group (-C=O) of amide molecules and hydroxyl group (-OH) of alcohol groups.

When third component PA is added to the equimolar mixture the existing hydrogen

bond between amide and alcohol groups is broken and a new hydrogen bond is

formed between unlike molecules of acid and alcohol groups. Moreover all the

components of the liquid mixtures studied are polar in nature having dipole moments

of methanol μ = 1.70 D, ethanol μ = 1.69 D, 1-propanol μ = 1.58 D, N,N-dimethyl

formamide μ = 3.82 and propanoic acid μ = 1.75. Therefore, dipole-dipole

236

interactions are also present in the liquid mixtures investigated. In addition to these,

physical interaction such as geometrical fitting of

242

smaller molecules into the voids created by the larger molecules is also favourable

for the present systems studied.

From figures 5.B.1 – 5.B.3 it is observed that, as the temperature of the

systems increases the negative excess molar volumes are found to decrease

indicating the decrease of interaction between the unlike molecules but the

interaction increases from MOH to POH. As the alkanol chain length increases,

decreasing the concentration of –OH groups in higher alkanols and thereby lowers

dipole moment in higher alkanols which causes weaker interactions. These are the

expected results, which we have observed that the strength of interaction increases as

we move from MOH to POH. This is due to the predomination of physical

interaction over chemical interaction between the unlike molecules, in other words,

geometrical fitting of smaller molecules into the voids created by the larger

molecules between the components of molecules of the liquid mixtures. Such similar

studies were reported by Harsha Kumar et al [46]. The strength of interactions in the

mixtures follows the order (DMF+MOH)+PA<

(DMF+EOH)+PA<(DMF+POH)+PA. The above discussion is also supported by the

observed positive values of Δη and ΔG*E.

Generally, negative values of Δη indicate the presence of dispersion forces or

mutual loss of specific interactions in like molecules operating in the systems arising

due to weak intermolecular interactions and positive values of deviation in viscosity

indicate the presence of strong interactions [25,26]. The sign and magnitude of Δη

depend on the combined effect of factors such as molecular size, shape, and

intermolecular forces. From the above observations it has been clear that as the

temperature increases the interaction between unlike molecules decreases.

243

The deviation/excess properties have been fitted to Redlich-Kister type

polynomial [29] equation (3.28). The coefficients Ai (A0 to A4) are determined using

the least square method. The corresponding standard deviations ( )EY are

calculated using the relation 3.29. The coefficients, Ai and the standard deviations, σ

of all the liquid mixtures have been presented in Table 5.B.5.

The partial molar volumes ,1mV of component 1 (propanoic acid) and ,2mV of

component 2 (N,N-dimethyl formamide + methanol/ethanol/1-propanol) in the

mixtures over the entire composition range are calculated by using the relations 3.30

to 3.33 which are described in chapter 3. The excess partial molar volumes ,1EmV and

,2EmV are calculated using the relations 3.34 and 3.35. The values of ,1mV and ,2mV are

furnished in Table 5.B.6. From the above table, the values of ,1mV and ,2mV for both

the components in the mixtures are lesser than their respective molar volumes in the

pure state. The variation of excess partial molar volumes, ,1EmV (PA), ,2

EmV (Equimolar

mixture DMF+MOH/EOH/POH) with mole fraction of PA for (DMF+MOH)+PA,

(DMF+EOH)+PA and (DMF+POH)+PA mixtures are shown in Figures 5.B.10,

5.B.11 and 5.B.12 respectively. From these figures, it reveals that, the excess partial

molar volumes are almost negative over the entire composition range is studied. This

suggest that there is a contraction of volume occurs in the binary mixtures, indicating

the presence of strong interactions between the unlike molecules of the mixtures as

observed in EVm . The partial molar volumes, ,1mV

, ,2mV

and excess partial molar

volumes,,,1

EmV

, ,,2

EmV

of the components at infinite dilution are obtained using the

equations 3.36 and 3.37.

244

Table 5.B.5 Coefficients Ai of Redlich-Kister type polynomial equation (3.28) and the corresponding standard deviations, σ (3.29) of all the systems under investigation property A0 A1 A2 A3 A4 σ (DMF+MOH)+PA

T = 303.15 K

V E

m/ 10-5m3.mol-1 -0.212 0.152 -0.112 0.085 0.067 0.001

Δη/10-3N.s.m-2 1.684 -1.834 0.075 1.194 -0.998 0.007

ΔG*E/kJ.mol-1 4347.49 -3147.14 125.71 1380.25 -1897.60 15.47

T = 313.15 K

V E

m/ 10-5m3.mol-1 -0.167 0.221 -0.142 0.024 0.116 0.001

Δη/10-3N.s.m-2 1.237 -1.415 -0.137 1.095 -0.436 0.005

ΔG*E/kJ.mol-1 3946.00 -2985.68 -630.10 1995.54 -626.08 12.42

T = 323.15 K

V E

m/ 10-5m3.mol-1 -0.145 0.237 0.065 0.208 0.128 0.002

Δη/10-3N.s.m-2 0.981 -1.225 -0.153 1.118 0.670 0.004

ΔG*E/kJ.mol-1 3830.37 -3353.06 -668.67 2795.34 -1949.20 15.35

(DMF+EOH)+PA

T = 303.15 K

V E

m/ 10-5m3.mol-1 -0.234 0.205 -0.271 0.029 0.202 0.001

Δη/10-3N.s.m-2 1.880 -1.507 -0.044 0.479 -0.436 0.011

ΔG*E/kJ.mol-1 4413.56 -2421.62 141.39 -78.65 -611.31 20.74

T = 313.15 K

V E

m/ 10-5m3.mol-1 -0.202 0.169 -0.276 0.134 0.344 0.001

Δη/10-3N.s.m-2 1.410 -1.104 -0.003 0.560 -0.778 0.004

ΔG*E/kJ.mol-1 4042.90 -2085.25 346.74 442.86 -2174.14 12.54

245

T = 323.15 K

V E

m/ 10-5m3.mol-1 -0.171 0.137 -0.134 0.155 0.148 0.001

Δη/10-3N.s.m-2 1.120 -1.001 0.257 0.708 -1.120 0.003

ΔG*E/kJ.mol-1 3937.77 -2516.18 1127.00 1348.04 -3656.51 11.30

(DMF+POH)+PA

T = 303.15 K

V E

m / 10-5m3.mol-1 -0.332 0.132 -0.073 0.085 -0.086 0.001

Δη/10-3N.s.m-2 1.967 -1.605 -0.102 0.550 0.284 0.009

ΔG*E/kJ.mol-1 4206.97 -2745.07 89.29 130.35 1209.09 15.72

T = 313.15 K

V E

m / 10-5m3.mol-1 -0.312 0.133 -0.101 0.055 0.112 0.001

Δη/10-3N.s.m-2 1.526 -1.003 -0.291 0.569 0.305 0.007

ΔG*E/kJ.mol-1 3941.34 -2013.12 -274.16 735.52 1043.917 7.96

T = 323.15 K

V E

m/ 10-5m3.mol-1 -0.298 0.145 -0.077 0.014 0.149 0.002

Δη/10-3N.s.m-2 1.282 -0.903 -0.341 0.523 0.437 0.004

ΔG*E/kJ.mol-1 4048.70 -2300.52 -594.56 868.89 1682.83 9.59

246

Table 5.B.6 Partial molar volumes as function of mole fraction of PA, x of all the liquid mixtures at 303.15, 313.15 and 323.15 K (DMF+MOH)+PA (DMF+EOH)+PA (DMF+POH)+PA x ,1V m ,2V m x ,1V m ,2V m x ,1V m ,2V m 10-5 m3.mol-1 10-5 m3.mol-1 10-5 m3.mol-1 T = 303.15 K 0.0000 7.523 5.892 0.0000 7.473 6.834 0.0000 7.269 7.657 0.1142 7.420 5.897 0.1110 7.386 6.837 0.1109 7.332 7.654 0.2189 7.416 5.896 0.2185 7.415 6.827 0.2178 7.357 7.648 0.3240 7.432 5.887 0.3265 7.438 6.813 0.3264 7.382 7.637 0.4218 7.444 5.878 0.4235 7.438 6.808 0.4283 7.408 7.620 0.5248 7.455 5.868 0.5197 7.433 6.811 0.5306 7.435 7.594 0.6225 7.468 5.853 0.6276 7.443 6.805 0.6279 7.458 7.565 0.7209 7.488 5.821 0.7309 7.474 6.765 0.7279 7.482 7.522 0.8156 7.513 5.758 0.8216 7.509 6.690 0.8185 7.505 7.455 0.9074 7.534 5.656 0.9121 7.536 6.599 0.9097 7.529 7.314 1.0000 7.543 5.511 1.0000 7.543 6.569 1.0000 7.543 7.024 T = 313.15 K 0.0000 7.664 5.955 0.0000 7.780 6.875 0.0000 7.498 7.739 0.1142 7.542 5.961 0.1110 7.461 6.888 0.1109 7.400 7.743 0.2189 7.522 5.962 0.2185 7.465 6.882 0.2178 7.418 7.737 0.3240 7.518 5.961 0.3265 7.510 6.860 0.3264 7.456 7.721 0.4218 7.514 5.960 0.4235 7.522 6.848 0.4283 7.484 7.702 0.5248 7.514 5.959 0.5197 7.516 6.851 0.5306 7.506 7.681 0.6225 7.527 5.946 0.6276 7.519 6.855 0.6279 7.529 7.652 0.7209 7.552 5.906 0.7309 7.547 6.824 0.7279 7.558 7.600 0.8156 7.581 5.833 0.8216 7.581 6.753 0.8185 7.585 7.526 0.9074 7.603 5.738 0.9121 7.605 6.678 0.9097 7.604 7.431 1.0000 7.610 5.659 1.0000 7.610 6.714 1.0000 7.610 7.350

247

T = 323.15 K 0.0000 8.198 5.986 0.0000 7.841 6.950 0.0000 7.639 7.827 0.1142 7.707 6.012 0.1110 7.605 6.976 0.1109 7.512 7.832 0.2189 7.582 6.034 0.2185 7.584 6.981 0.2178 7.521 7.828 0.3240 7.573 6.038 0.3265 7.609 6.958 0.3264 7.554 7.814 0.4218 7.593 6.027 0.4235 7.624 6.939 0.4283 7.579 7.797 0.5248 7.615 6.007 0.5197 7.629 6.933 0.5306 7.602 7.776 0.6225 7.635 5.979 0.6276 7.636 6.921 0.6279 7.628 7.742 0.7209 7.657 5.927 0.7309 7.654 6.872 0.7279 7.660 7.682 0.8156 7.680 5.838 0.8216 7.677 6.797 0.8185 7.687 7.603 0.9074 7.698 5.703 0.9121 7.698 6.766 0.9097 7.703 7.526 1.0000 7.706 5.523 1.0000 7.706 6.967 1.0000 7.706 7.519

251

The pertinent values of ,1mV

,2mV ,

,1EmV

and ,,2

EmV

are shown in Table 5.B.7. From the

above table these values are negative concluded that strong interactions exist in the

unlike molecules of the components. The magnitude of excess partial molar volumes

at infinite dilution also follow the order (DMF+POH)+PA > (DMF+EOH)+PA >

(DMF+MOH)+PA which supports the trends of EVm values very well those observed

in these mixtures.

The dynamic viscosities of the investigated liquid mixtures have been

calculated using the Grunberg and Nissan [30], Hind and Ubbelohde [31], Katti and

Chaudari [32], Heric and Brewer [33] relations. The theoretical values of viscosity of

the (DMF+MOH)+PA, (DMF+EOH)+PA and (DMF+POH)+PA liquid mixtures

calculated using the above theories are compiled in Tables 5.B.8, 5.B.9 and 5.B.10

respectively. Table 5.B.11 presents the values of the interaction parameters along

with the standard deviations, σ. The terms G12, H12, Wvis and Δ12 are adjustable

parameters representing the binary interactions. The variation of these parameters

with composition follows the order (DMF+POH)+PA > (DMF+EOH)+PA >

(DMF+MOH)+PA at constant temperature. Further the interaction parameter values

are found to decrease with an increase in temperature of all the systems studied.

These results are in good agreement with the results derived from the excess

properties. Prolongo et al [34] reported positive values of interaction parameter

corresponding to systems with negative excess molar volumes. This is in good

agreement with our results. The estimated values of σ are smaller indicating that

experimental values of viscosities are well correlated by all the four viscosity

models.

252

Table 5.B.7 The values of ,1mV

, 1V ,,,1

EmV

, ,2mV

, 2V ,,,2

EmV

for all liquid mixtures at T = (303.15, 313.15 and 323.15) K ,1mV

1V

,,1

EmV

,2mV

2V ,,2

EmV

10-5m3.mol-1 (DMF+MOH)+PA

T = 303.15 K

7.523 7.543 -0.020 5.399 5.892 -0.494

T = 313.15 K

7.664 7.610 0.053 5.517 5.955 -0.438

T = 323.15 K

8.198 7.706 0.493 5.588 5.986 -0.398

(DMF+EOH)+PA

T = 303.15 K

7.473 7.543 -0.070 6.298 6.834 -0.537

T = 313.15 K

7.780 7.610 0.169 6.438 6.875 -0.437

T = 323.15 K

7.841 7.706 0.136 6.501 6.950 -0.449

(DMF+POH)+PA

T = 303.15 K

7.269 7.543 -0.274 6.950 7.657 -0.707

T = 313.15 K

7.498 7.610 -0.113 7.250 7.739 -0.489

T = 323.15 K

7.639 7.706 -0.067 7.442 7.827 -0.385

253

Table 5.B.8 Theoretical values of viscosities from eqn.s [(3.47)-(3.53)] with mole fraction of PA, x for (DMF+MOH)+PA at 303.15, 313.15 and 323.15 K



0.0000 0.674 0.674 0.674 0.674 0.1142 0.831 0.869 0.829 0.831 0.2189 0.969 1.011 0.966 0.968 0.3240 1.089 1.117 1.086 1.088 0.4218 1.174 1.185 1.172 1.174 0.5248 1.227 1.222 1.227 1.227 0.6225 1.239 1.225 1.240 1.239 0.7209 1.210 1.198 1.213 1.211 0.8156 1.148 1.142 1.151 1.149 0.9074 1.060 1.060 1.062 1.060 1.0000 0.950 0.950 0.950 0.950

T = 313.15 K

0.0000 0.580 0.580 0.580 0.580 0.1142 0.701 0.729 0.699 0.700 0.2189 0.806 0.839 0.804 0.806 0.3240 0.900 0.923 0.897 0.899 0.4218 0.968 0.979 0.966 0.968 0.5248 1.015 1.013 1.014 1.015 0.6225 1.031 1.022 1.033 1.032 0.7209 1.020 1.009 1.022 1.020 0.8156 0.982 0.975 0.985 0.983 0.9074 0.924 0.921 0.926 0.924 1.0000 0.848 0.848 0.848 0.848

T = 323.15 K

0.0000 0.503 0.503 0.503 0.503 0.1142 0.595 0.615 0.592 0.595 0.2189 0.674 0.697 0.671 0.674 0.3240 0.743 0.760 0.741 0.743 0.4218 0.793 0.801 0.792 0.793 0.5248 0.827 0.827 0.828 0.827 0.6225 0.839 0.834 0.841 0.839 0.7209 0.831 0.825 0.834 0.831 0.8156 0.804 0.800 0.807 0.804 0.9074 0.762 0.761 0.764 0.762 1.0000 0.706 0.706 0.706 0.706

254

Table 5.B.9 Theoretical values of viscosities from eqn.s [(3.47)-(3.53)] with mole fraction of PA, x for (DMF+EOH)+PA at 303.15, 313.15 and 323.15 K



0.0000 0.758 0.758 0.758 0.758 0.1110 0.929 0.962 0.927 0.929 0.2185 1.084 1.116 1.081 1.084 0.3265 1.214 1.228 1.211 1.214 0.4235 1.297 1.291 1.293 1.296 0.5197 1.338 1.320 1.336 1.338 0.6276 1.332 1.311 1.332 1.332 0.7309 1.275 1.262 1.279 1.276 0.8216 1.189 1.187 1.193 1.189 0.9121 1.076 1.081 1.079 1.076 1.0000 0.950 0.950 0.950 0.950

T = 313.15 K

0.0000 0.649 0.649 0.649 0.649 0.1110 0.778 0.804 0.776 0.778 0.2185 0.895 0.922 0.892 0.894 0.3265 0.993 1.009 0.991 0.993 0.4235 1.058 1.061 1.056 1.058 0.5197 1.095 1.088 1.093 1.095 0.6276 1.099 1.088 1.100 1.099 0.7309 1.068 1.058 1.070 1.068 0.8216 1.013 1.009 1.015 1.013 0.9121 0.937 0.938 0.939 0.937 1.0000 0.848 0.848 0.848 0.848

T = 323.15 K

0.0000 0.563 0.563 0.563 0.563 0.1110 0.666 0.684 0.664 0.666 0.2185 0.757 0.777 0.755 0.757 0.3265 0.833 0.845 0.832 0.833 0.4235 0.882 0.885 0.881 0.882 0.5197 0.909 0.905 0.908 0.909 0.6276 0.910 0.903 0.911 0.911 0.7309 0.883 0.878 0.885 0.884 0.8216 0.839 0.838 0.841 0.839 0.9121 0.778 0.780 0.779 0.778 1.0000 0.706 0.706 0.706 0.706

255

Table 5.B.10 Theoretical values of viscosities from eqn.s [(3.47)-(3.53)] with mole fraction of PA, x for (DMF+POH)+PA at 303.15, 313.15 and 323.15 K



0.0000 0.893 0.893 0.893 0.893 0.1109 1.077 1.100 1.076 1.077 0.2178 1.237 1.252 1.234 1.237 0.3264 1.363 1.359 1.360 1.363 0.4283 1.436 1.416 1.433 1.436 0.5306 1.456 1.431 1.455 1.456 0.6279 1.424 1.405 1.424 1.424 0.7279 1.343 1.338 1.344 1.343 0.8185 1.233 1.242 1.236 1.233 0.9097 1.098 1.112 1.100 1.098 1.0000 0.950 0.950 0.950 0.950

T = 313.15 K

0.0000 0.764 0.764 0.764 0.764 0.1109 0.906 0.922 0.905 0.906 0.2178 1.028 1.039 1.026 1.028 0.3264 1.126 1.123 1.124 1.126 0.4283 1.184 1.169 1.183 1.184 0.5306 1.205 1.184 1.205 1.205 0.6279 1.187 1.169 1.188 1.187 0.7279 1.133 1.124 1.135 1.133 0.8185 1.056 1.057 1.058 1.056 0.9097 0.958 0.964 0.960 0.958 1.0000 0.848 0.848 0.848 0.848

T = 323.15 K

0.0000 0.655 0.655 0.655 0.655 0.1109 0.773 0.787 0.772 0.773 0.2178 0.874 0.884 0.872 0.874 0.3264 0.954 0.953 0.953 0.954 0.4283 1.000 0.990 0.999 1.000 0.5306 1.015 1.001 1.015 1.015 0.6279 0.997 0.986 0.998 0.997 0.7279 0.949 0.946 0.951 0.949 0.8185 0.883 0.887 0.885 0.883 0.9097 0.800 0.807 0.800 0.800 1.0000 0.706 0.706 0.706 0.706

256

Table 5.B.11 Various interaction parameters calculated from eqns. [(3.47)-(3.53)] and the corresponding standard deviations (σ/10-3 N.s.m-2)

T/K G12 σ H12 σ Wvis/RT σ Δ12 σ

(DMF+MOH)+PA

303.15 1.682 0.109 0.002 0.131 1.677 0.107 1.740 0.108

313.15 1.446 0.079 0.001 0.097 1.448 0.076 1.504 0.078

323.15 1.277 0.071 0.001 0.082 1.292 0.069 1.335 0.071

(DMF+EOH)+PA

303.15 1.808 0.103 0.002 0.120 1.772 0.100 1.831 0.103

313.15 1.538 0.068 0.001 0.084 1.510 0.066 1.562 0.068

323.15 1.449 0.061 0.001 0.071 1.428 0.059 1.473 0.061

(DMF+POH)+PA

303.15 1.833 0.126 0.002 0.128 1.784 0.123 1.838 0.126

313.15 1.607 0.068 0.002 0.073 1.564 0.066 1.613 0.068

323.15 1.596 0.063 0.001 0.066 1.556 0.061 1.601 0.062

257

Conclusions

(i) The densities and viscosities of liquid mixtures of propanoic acid with equimolar

mixture of N,N-dimethyl formamide and methanol/ethanol/1-propanol have been

measured over the entire composition range at T = 303.15, 313.15 and 323.15 K

and the properties like, EmV , , EG , ,1mV , ,2mV , ,1

EmV , and ,2

EmV have been

computed from the experimental results.

(ii) The values of EVm are negative and Δη, ΔG*E are positive at all temperatures studied,

indicating the presence of strong interactions (hydrogen bonding O…..H-O-) such

as interactions between carbonyl group(-C=O) of amide molecules and hydroxyl

group(-OH) of alcohol groups and also the intermolecular interactions between

carbonyl group(-C=O) of acid molecules and hydroxyl group(-OH) of alcohols,

dipole-dipole interactions and geometrical fitting of smaller molecules into the

voids created by the larger molecules in the investigated systems.

(iii) The strength of interactions follows the order (DMF+MOH) +PA < (DMF+EOH)

+PA < (DMF+POH) +PA.

(iv) The strength of interactions is also studied with the variation of temperature.

(v) The experimental viscosity values are compared with the viscosity values obtained

from different empirical relations and these are in good agreement with the

experimental values.

258

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