The study of partial and excess molar volumes for binary mixtures of nitrobenzene and benzaldehyde with xylene isomers from T = (298.15 to 318.15) K and P = 0.087 MPa

Based on density measurements, partial and excess molar volumes for binary mixtures of nitrobenzene and benzaldehyde with three isomers of xylene have been measured. The whole range of composition and temperatures from T = (298.15 to 318.15) K at ambient pressure 0.087 MPa, has been considered. The excess molar volumes were negative and decreased by increasing temperature for all mixtures which are explained based on intermolecular interactions. Excess molar volumes for solutions including nitrobenzene were absolutely larger than benzaldehyde binary mixtures. The partial and excess molar volumes for each component have been appraised and reported. The excess molar volumes have been successfully fitted to Redlich–Kister equation.

ORIGINAL ARTICLE

The study of partial and excess molar volumes for

binary mixtures of nitrobenzene and benzaldehyde

Department of Physical Chemistry, Faculty of Chemistry, Razi University, Kermanshah 67149, Iran

A R T I C L E I N F O

Article history:

Received 14 August 2015

Received in revised form 9 November 2015

Accepted 16 November 2015

Available online 28 November 2015

Keywords:

Density

Redlich–Kister

Volumetric

Excess molar volume

Xylenes

A B S T R A C T

Based on density measurements, partial and excess molar volumes for binary mixtures of nitrobenzene and benzaldehyde with three isomers of xylene have been measured The whole range of composition and temperatures from T = (298.15 to 318.15) K at ambient pressure 0.087 MPa, has been considered The excess molar volumes were negative and decreased by increasing temperature for all mixtures which are explained based on intermolecular interac-tions Excess molar volumes for solutions including nitrobenzene were absolutely larger than benzaldehyde binary mixtures The partial and excess molar volumes for each component have been appraised and reported The excess molar volumes have been successfully fitted to Redlich–Kister equation

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Introduction

Liquid mixtures are important from both theoretical and

prac-tical points of view From theoreprac-tical viewpoint, developing

the knowledge of molecular interactions could help to predict

thermodynamics and transport properties of components In

the other hand, mixtures are encountered more in practice,

in laboratory and in processes thereby attracting more atten-tion Volumetric properties of binary mixtures are complicated properties since they depend not only on solvent–solvent, solute–solute and solute–solvent interactions, but also on the structural effects arising from differences in molar volume and free volume between solution components Benzaldehyde

is used chiefly as a precursor to other organic compounds, ranging from pharmaceuticals to plastic additives while the most application of nitrobenzene is in the production of aniline which is a precursor to rubber chemicals, pesticide, dyes (par-ticularly azo-dyes), explosives, and pharmaceuticals Xylenes are important in organic synthesis and their volumetric behav-ior in their mixtures with nitrobenzene and benzaldehyde may

* Corresponding author Tel./fax: +98 833 4274559

E-mail address:rafieehr@yahoo.com(H.R Rafiee)

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be useful in process design, modeling and synthesis reactions

which involve these binary systems There are several reports

about the experimental data of volumetric and viscometric

behaviors for binary and ternary liquid mixtures including

benzene and its derivatives [1–5] There are also some

semi-empirical relations that have been proposed to evaluate excess

properties from experimental data for binary [6–11] and

ternary mixtures [12–19] In our previous work [20] we

reported volumetric properties of binary and ternary mixtures

of 1,4-dioxane, cyclohexanone and isooctane In this work we

focused on volumetric properties of six binary mixtures of

nitrobenzene and benzaldehyde with three isomers of xylene

for whole range of composition at ambient pressure and

temperatures from T = 298.15 to 318.15 K By measuring

densities we evaluated both excess molar and partial molar

volumes of components Moreover their behaviors are

discussed in detail based on intermolecular interactions.

Experimental

Material

Benzaldehyde and m-xylene with minimum mass fraction

purity >0.99, were obtained from the Merck Nitrobenzene,

o-xylene and p-xylene with minimum mass fraction purity

>0.99, were obtained from the BDH All materials were used

without further purification Properties of used materials are

tabulated in Table 1

Apparatus and procedure

All solutions were prepared afresh by mass using an analytical

balance (Sartorius, CP224S, Germany) with precision (10
4g).

The average uncertainty in the mole fraction of the mixtures

was estimated to be less than ±0.0002 Caution was taken

to prevent evaporation of the samples and measurements were

performed immediately after preparation of solutions The

densities of solutions were measured by means of an Anton

Parr DMA 4100 U-tube densimeter The apparatus was

cali-brated with double distilled deionized, and degassed water,

and dry air at atmospheric pressure All injections to

densime-ter were done by using micro lidensime-ter syringe for afresh prepared

solutions Temperature was automatically kept constant

within ±0.05 K by instrument Before injection, all samples

were degassed by using ultrasound instrument (Hielscher

UP100H, Germany) All measurements were performed at

least three times, and the reported values are the relevant

aver-ages The experimental uncertainty of density measurements

was ±5  10
4g cm
3 The pressure in our laboratory was

constant at 0.087 MPa with standard uncertainty of 5 kPa.

Results and discussion

Table 2 includes measured and reported values for density of pure components Fig 1 demonstrates a deviation plot to com-pare reported and measured densities at different tempera-tures Deviations have been calculated as follows:

Dev % ¼ ½ðqexp
qreportÞ=qexp  100 ð1Þ where qexpand qreportstand for measured and reported densi-ties, respectively As can be seen the agreement between our data with literature reports is good.

Using the measured densities q, excess molar volumes are calculated by the following equation:

VE

m¼ X

i

1

q

1

qi

in which q is density of mixture and qi, xiand Miare density, mole fraction and molar mass of pure component i,

respec-Table 1 Provenance and mass fraction purity of the compounds studied

components.a Components T (K) q (g cm
3) q (g cm
3)

This work Literature

a Uncertainty for measured densitiesq = ±5  10
4g cm
3

tively The partial molar volumes Vm,iare appraised based on

following equations [25,26] :

Vm;1¼ V

1þ 1
x ð Þ2Xj

i¼0

Aið 1
2x Þi

2x 1
x ð Þ2Xj

i¼1

Vm;2¼ V

2þ x2Xj

i¼0

Aið 1
2x Þiþ 2x2ð1
xÞ X

j

i¼1

Aii 1
2x ð Þi
1

ð4Þ where x stands for mole fraction, Aiis the coefficient which

comes from fitting by Redlich–Kister equation [27] and Vi*is

molar volume of pure component i Excess partial molar

volumes VEm,1 and VEm,2 are then calculated as (Vm,1
V1)

and (Vm,2
V2).

The Redlich–Kister equation is as follows:

VE

m¼ x1x2

Xj

i¼0

Tables 3–8 present the densities, excess volumes, partial molar

and excess partial molar volumes for six binary studied

systems.

Also the excess molar volumes are fitted to Redlich–Kister

equation using least square method (minimizing the sum of

squared of difference between the experimental data and the

calculated values from Eq (5) ) This is done by using the

MathCAD 11(2001i) software using conjugate gradient

algo-rithm This is the preferred algorithm by the MathCAD 11

(2001i) software for the minimizing Standard deviations are

calculated using the following equation:

r ¼

PN

i¼1 VE

exp
VE

calc

N
P

0

@

1 A 1

ð6Þ

where P is the number of parameters and N is the number of

experimental data.

The Aicoefficients for the binary mixtures, at different tem-peratures along with their relevant standard deviations r, are given in Table 9

The values of standard deviations show that the fitting is very good.

As can be seen from Tables 3–8 all six mixtures show neg-ative excess volumes over entire range of composition which are reduced by growing temperature There are two important factors that affect the excess volume behavior in binary mix-tures:(a) the intermolecular interactions (including dipole– dipole interactions, cohesive and dispersive forces and hydrogen-bonding)and (b) the size, shape and packing ability

of component’s molecules (geometrical factors) in solution The negative excess volume comes from stronger intermolecu-lar interactions in mixture compared to pure components That is, contraction takes place in volume by mixing How-ever, inverse trend would be expected when expansion in volume occurs on mixing which implies that structural (repul-sive) effects are govern and prevailing to attractive interactions

in solution Tables 3–8 show that the values of excess molar volumes are absolutely larger, in nitrobenzene mixtures, com-pared to benzaldehyde ones These larger values can be attrib-uted to more polarity of nitrobenzene which leads to stronger attractive forces Further considering the tables also reveals that in both nitrobenzene and benzaldehyde solutions, for meta and para-xylene mixtures, excess volumes are relatively higher than those for ortho-xylene mixtures This behavior can be explained by noting to configurations of these mole-cules In ortho-xylene two vicinal methyl groups extend the steric restrain of molecule which in turn leads to weaker inter-actions with nitrobenzene or benzaldehyde The effect is less in meta or para isomer which shows relatively larger negative values of excess volumes.

Figs 2–4 illustrate the plot of excess volumes for binary mixtures of nitrobenzene against mole fraction of xylene For comparison, the reported results of Wang et al [3] are also shown Figures illustrate that by noting to the negative values

of excess volumes, there is agreement in the trend of data The figures show that by increasing temperature excess volumes reduce and tend to more negative values Valtz and his coworkers haveobserved similar behavior for some (triethylene glycol + alcohol) binary systems They explained this observa-tion by the packing effects which become more dominant by increasing temperature [28] The same behavior is also observed for poly (ethylene glycol) + methoxybenzene or ethoxybenzene binary solutions [29] ; pyridine + polyols bin-ary solutions [30] and methoxybenzene + xylenes binary mix-tures [31] This behavior may be justified based on growing packing ability of components by raising their kinetic energy.

By referring to Figs 2–7 it can be seen that the effect of tem-perature is to decrease the excess volume values in all binary studied systems This means that by increasing temperature, the attractive interactions are amplified in all six mixtures However, again, the nitrobenzene mixtures, compared to ben-zaldehyde solutions, prove relatively more sensitivity to this variation Thus, for example, charge transfer or any interac-tion complexes maybe formed between nitrobenzene (or ben-zaldehyde) and xylene [32] By increasing temperature, structural factors may show favorable effect and thereby solu-tion exhibits more compact structure at higher temperature As

-0.1

-0.08

-0.06

-0.04

-0.02

0

0.02

0.04

0.06

295 300 305 310 315 320

T / K

Fig 1 Deviation plot for pure component’s densities at studied

p-xylene, , benzaldehyde

Table 3 Densities q, excess molar volumes VmE, partial molar volumes Vm,i and excess partial molar volumes Vm,i of x o-xylene (o-C8H10) + 1
x benzaldehyde (C7H6O) at T = (298.15 to 318.15) K and ambient pressure.a

x q (g cm
3) VmE(cm
3mol
1) Vm,1(cm
3mol
1) Vm,2(cm
3mol
1) Vm,1E(cm
3mol
1) Vm,2E(cm
3mol
1)

T = 298.15 K

T = 303.15 K

T = 308.15 K

T = 313.15 K

T = 318.15

Table 4 Densities q, excess molar volumes VmE, partial molar volumes Vm,iand excess partial molar volumes Vm,i of x m-xylene (m-C8H10) + 1
x benzaldehyde (C7H6O) at T = (298.15 to 318.15) K and ambient pressure.a

x q (g cm
3) VmE(cm
3mol
1) Vm,1(cm
3mol
1) Vm,2(cm
3mol
1) Vm,1E(cm
3mol
1) Vm,2E(cm
3mol
1)

T = 298.15 K

T = 303.15 K

T = 308.15 K

T = 313.15 K

T = 318.15

a

Uncertainties for x = 0.0002 q = ±5  10
4(g cm
3) and for VE, V and V E= ±0.0005 (cm
3mol
1)

Table 5 Densities q, excess molar volumes VmE, partial molar volumes Vm,i and excess partial molar volumes Vm,i of x p-xylene (p-C8H10) + 1
x benzaldehyde (C7H6O) at T = (298.15 to 318.15) K and ambient pressure.a

x q (g cm
3) VmE(cm
3mol
1) Vm,1(cm
3mol
1) Vm,2(cm
3mol
1) Vm,1E(cm
3mol
1) Vm,2E(cm
3mol
1)

T = 298.15 K

0.0000 1.0414 0.0000

0.0701 1.0270
0.1119 123.0228 101.9113
0.9062 0.0004

0.1032 1.0204
0.1707 123.1243 101.9077
0.8047
0.0032

0.2007 1.0002
0.2128 123.3062 101.8759
0.6228
0.0350

0.3038 0.9796
0.2475 123.4404 101.8150
0.4886
0.0959

0.4025 0.9605
0.2614 123.5485 101.7323
0.3805
0.1786

0.5013 0.9419
0.2499 123.6300 101.6090
0.2990
0.3019

0.5944 0.9250
0.2377 123.6883 101.4386
0.2407
0.4723

0.6974 0.9069
0.2112 123.7531 101.1836
0.1759
0.7273

0.7999 0.8894
0.1596 123.8311 100.8627
0.0979
1.0482

0.8992 0.8730
0.0998 123.9014 100.4335
0.0276
1.4774

1.0000 0.8567 0.0000

T = 303.15 K

0.0000 1.0369 0.0000

0.0701 1.0224
0.1112 123.5968 102.3646
0.9574 0.0016

0.1032 1.0160
0.1903 123.7209 102.3627
0.8333
0.0003

0.2007 0.9958
0.2308 123.9424 102.3364
0.6118
0.0266

0.3038 0.9752
0.2633 124.0754 102.2747
0.4788
0.0883

0.4025 0.9561
0.2746 124.1624 102.1786
0.3918
0.1844

0.5013 0.9375
0.2599 124.2250 102.0307
0.3292
0.3323

0.5944 0.9206
0.2442 124.2766 101.8306
0.2776
0.5324

0.6974 0.9025
0.2133 124.3463 101.5384
0.2079
0.8246

0.7999 0.8851
0.1702 124.4359 101.1794
0.1183
1.1836

0.8992 0.8687
0.1056 124.5189 100.7297
0.0353
1.6333

1.0000 0.8524 0.0000

T = 308.15 K

0.0000 1.0324 0.0000

0.0701 1.0179
0.1125 124.2055 102.8102
0.9950 0.0009

0.1032 1.0115
0.1924 124.3254 102.8072
0.8751
0.0021

0.2007 0.9913
0.2334 124.5438 102.7768
0.6567
0.0325

0.3038 0.9707
0.2657 124.6923 102.7141
0.5082
0.0952

0.4025 0.9516
0.2764 124.8005 102.5795
0.4000
0.1863

0.5013 0.9331
0.2724 124.8781 102.5055
0.3224
0.3255

0.5944 0.9162
0.2556 124.9345 102.3882
0.2660
0.5181

0.6974 0.8981
0.2227 125.0021 102.1694
0.1984
0.8052

0.7999 0.8807
0.1772 125.0877 101.8029
0.1128
1.1646

0.8992 0.8643
0.1095 125.1674 101.3463
0.0331
1.6313

1.0000 0.8480 0.0000

T = 313.15 K

0.0000 1.0279 0.0000

0.0701 1.0135
0.1253 124.7505 103.2679
1.1179 0.0085

0.1032 1.0070
0.1961 124.9433 103.2691
0.9251 0.0097

0.2007 0.9868
0.2389 125.2237 103.2412
0.6447
0.0182

0.3038 0.9662
0.2728 125.3602 103.1694
0.5082
0.0900

0.4025 0.9471
0.2842 125.4589 103.0693
0.4095
0.1901

0.5013 0.9286
0.2805 125.5381 102.9260
0.3303
0.3334

0.5944 0.9117
0.2633 125.6021 102.7374
0.2663
0.5220

0.6974 0.8936
0.2295 125.6814 102.4727
0.1870
0.7867

0.7999 0.8763
0.1963 125.7757 102.1561
0.0927
1.1033

0.8992 0.8599
0.1270 125.8494 101.6908
0.0190
1.5686

1.0000 0.8436 0.0000

T = 318.15

0.0000 1.0234 0.0000

0.0701 1.0089
0.1174 125.3371 103.7265
1.2064 0.0130

0.1032 1.0025
0.1999 125.5682 103.7294
0.9753 0.0159

0.2007 0.9823
0.2446 125.8599 103.6956
0.6836
0.0179

0.3038 0.9617
0.2799 125.9797 103.6080
0.5638
0.1055

0.4025 0.9427
0.3041 126.0870 103.4982
0.4565
0.2153

0.5013 0.9242
0.3011 126.1927 103.3593
0.3508
0.3542

0.5944 0.9073
0.2841 126.2844 103.1933
0.2591
0.5202

0.6974 0.8892
0.2499 126.3868 102.9826
0.1567
0.7309

0.7999 0.8718
0.2019 126.4872 102.7491
0.0563
0.9644

0.8992 0.8555
0.1448 126.5449 102.3343 0.0014
1.3792

1.0000 0.8393 0.0000

Table 6 Densities q, excess molar volumes VmE, partial molar volumes Vm,iand excess partial molar volumes Vm,iof x o-xylene (o-C8H10) + 1
x nitro benzene (C6H5NO2) at T = (298.15 to 318.15) K and ambient pressure.a

x q (g cm
3) VmE(cm
3mol
1) Vm,1(cm
3mol
1) Vm,2(cm
3mol
1) Vm,1E(cm
3mol
1) Vm,2E(cm
3mol
1)

T = 298.15 K

T = 303.15 K

T = 308.15 K

T = 313.15 K

T = 318.15

a

Uncertainties for x = 0.0002 q = ±5  10–4(g cm
3) and for VmE, Vm,iand Vm,iE= ±0.0005 (cm
3mol
1)

Table 7 Densities q, excess molar volumes VmE, partial molar volumes Vm,iand excess partial molar volumes Vm,iof x m-xylene (m-C8H10) + 1
x nitro benzene (C6H5NO2) at T = (298.15 to 318.15) K and ambient pressure.a

x q (g cm
3) VmE(cm
3mol
1) Vm,1(cm
3mol
1) Vm,2(cm
3mol
1) Vm,1E(cm
3mol
1) Vm,2E(cm
3mol
1)

T = 298.15 K

T = 303.15 K

T = 308.15 K

T = 313.15 K

T = 318.15

Table 8 Densities q, excess molar volumes VmE, partial molar volumes Vm,iand excess partial molar volumes Vm,iof x p-xylene (p-C8H10) + 1
x nitro benzene (C6H5NO2) at T = (298.15 to 318.15) K and ambient pressure.a

x q (g cm
3) VmE(cm
3mol
1) Vm,1(cm
3mol
1) Vm,2(cm
3mol
1) Vm,1E(cm
3mol
1) Vm,2E(cm
3mol
1)

T = 298.15 K

T = 303.15 K

T = 308.15 K

T = 313.15 K

T = 318.15 K

a

Uncertainties for x = 0.0002 q = ±5  10
4(g cm
3) and for VE, V and V E= ±0.0005 (cm
3mol
1)

Table 9 Coefficients of the Redlich–Kister equation, Eq (5) for excess molar volume of binary mixtures along with standard deviations,r, at various temperatures

Nitrobenzene + p-Xylene

Nitrobenzene + m-Xylene

Nitrobenzene + o-Xylene

Benzaldehyde + p-Xylene

Benzaldehyde + m-Xylene

Benzaldehyde + o-Xylene

-0.3

-0.2

-0.1

0

0.00 0.20 0.40 0.60 0.80 1.00

V m

3.mol

-1)

x

Fig 2 Excess molar volume for binary mixtures of o-(CH3)2

C6H4+ C6H5NO2 at T = 303.15 K and T = 313.15 K versus

o-xylene mole fraction T = 303.15 K: , this work, , Wang et al

[3], T = 313.15: , this work, , Wang et al.[3]; solid lines are

-0.50 -0.40 -0.30 -0.20 -0.10 0.00

0.00 0.20 0.40 0.60 0.80 1.00

V m

3.mol -1)

x

Fig 3 Excess molar volume for binary mixtures of m-(CH3)2

C6H4+ C6H5NO2 at T = 303.15 K and T = 313.15 K versus

et al.[3], T = 313.15: , this work, , Wang et al.[3]; solid lines