survismeter for simultaneous viscosity and surface tension study for molecular interactions

15

Research ArticleReceived: 16 September 2007 Accepted: 1 November 2007 Published online in Wiley Interscience: 4 January 2008

(www.interscience.com) DOI 10.1002/sia.2663

Survismeter for simultaneous viscosity andsurface tension study for molecularinteractionsMan Singh∗

Survismeter simultaneously measures viscosities and surface tensions of several standard solvents (AR, methanol, ethanol,glycerol, ethyl acetate, n-hexane, diethyl ether, chloroform, benzene, CCl4 and formic acid) and freshly prepared solutionsof urea (U), 1-methylurea (MU), 1,3-dimethylurea (DMU) at several temperatures. Analysis for accuracies and hydrophobicinteractions were made with data of solvents and solutions respectively. It replaces the use of viscometers and stalagmometerfor viscosity and surface tensions individually. A decrease with one –CH3 of MU and an increase with two –CH3 of DMU inviscosities for 288.15–298.15 K with reverse trend for 303.15–308.15 K are noticed. Surface tension decreases from U to MUand increases with DMU at a slightly higher rate, but decreases with temperature. The –CH3 is noticed to weaken hydrophilicinteractions and strengthening hydrophobic interactions with stronger structure effecting changes in MU and DMU. Copyrightc© 2008 John Wiley & Sons, Ltd.

Keywords: survismeter; viscosity; surface tension; dimethylurea; structure breaking

Introduction

Viscosities (η, N s m−2) and surface tensions (γ , N m−1) ofsolvents were compared with those of Ubbehold viscometerand stalagmometer respectively, with ±1.1 × 10−5 N s m−2 and±1.3 × 10−6 N m−1 deviations. The data are useful for processesthat deviate from ideal solutions.[1] Several chemical substancessuch as urea, guanidine hydrogen chloride, and dithioerythetoldo develop nonideal solutions and denature proteins and suchinformation on 1-methylurea (MU) and 1,3-dimethylurea (DMU)are interesting. The MU and DMU with –CH3 interact withpeptide bonds of proteins[2] offering as most formidable mediafor biochemical processes.[3 – 7] The –CH3 weakens the hydrogenbonding ability of –NH2 and (>C O)[8 – 25] groups. Viscosities andsurface tensions for antiwrinkle creams, facial creams, sunburn oilsand petroleum, sol-gels, emulsions, lotions, bio-fluids, inks, syrups,and coating materials etc. are useful. Similarly oil, blood, shampoo,and real-life fluids, which often do not perfectly obey a fairlystraightforward Bernoulli’s concept require such data. Jean LouisPoiseuille (Poise = P), a French physician studied blood viscosities(4 × 10−3 Pa s) with blood flow in small blood vessels with a flowrate proportional to r4, where r is a vessel diameter. A decrease inr by 2 reduces the flow rate by 16. It is a question of worry aboutcholesterol levels that clog arteries – even a minor change in sizeof a blood vessel can have a significant impact on the rate of bloodpumping by our heart. Viscosity in N s m−2 (SI), 1 P = 0.1 N s m−2,1 cP = 0.001 N s m−2, is an energy for flow because P N ms/m3 = N s/m2 as P = [Force, N)× (thickness, m)× (time, s)]/[(areaof tube, m2) × (distance, m)]. Similarly cohesion force is anintermolecular attraction between like molecules and adhesionbetween unlike molecules. High surface tensions show strongercohesion forces and poor wetting due to low adhesion forces and acapillary action to transport the liquid and nutrients in plants, andsometimes in animals. Hence survismeter is useful for such systems.

Experiment

Standard solvents [AR, Merck, India] were freshly distilledbefore they were used. The t was noted with 1 × 10−2 selectronic timer and n with a drop counter, respectively.[4,17]

Solutions, w/w, in deionized, triple-distilled water were degassedwith 1 × 10−6�−1 cm−1 conductivity. Urea, methylurea, anddimethylurea (AR E Merck) were dried overnight in a vacuumdesiccator for 24 h and stored in a P2O5 filled desiccator.

Survismeter

Survismeter (calibration, 06 070 582/1.01/C-0395, NPL-India) con-sists of six bulbs and five limbs; upper openings of limb numbers2, 3, 4, and 5 are made with standard glass joints $B 7 and $B10(Fig. 1).[4,17] Another end of limb number 1 is fused with bulb num-ber 10 and 2, 3, and 4 via bulb numbers 5, 6, 7, and 8 to bulb number9, while number 5 is attached with bulb number 10. Bulb number10 holds liquid, bulb number 9 and limb number 3 via tube number12 control pressure, capillaries are of 0.5 mm id and of 130-mmlength. Bulb number 10 holds 15×10−3 dm3 but 10×10−3 dm3 istaken with 5×10−3 dm3 empty volume for pressure. Bulb number9 holds 4 × 10−3 dm3, bulb numbers 8 of 5 × 10−3 dm3 and 7 isof 4 × 10−3 dm3. Survismeter constant with water is 0.1 m2 s−2.

Viscosities

Liquid from bulb number 10 is sucked to an upper mark ofbulb number 5 via bulb numbers 9 and 6, by blocking the joint

∗ Correspondence to: Man Singh, Chemistry Research lab, Deshbandhu College,University of Delhi, New Delhi, India. E-mail: [email protected]

Chemistry Research lab, Deshbandhu College, University of Delhi, New Delhi,India

Surf. Interface Anal. 2008; 40: 15–21 Copyright c© 2008 John Wiley & Sons, Ltd.

16

M. Singh

Figure 1. Numbers 1, 2, 3, 4, and 5 on upper ends of survismeter are limbs,and 5, 6, 7, 8, 9, and 10 are operational bulbs. The numbers depicted alongwith the vertical lines are dimensions of the instrument, and darkenedvertical tubes between the bulbs 6 and 9, and 8 and 9, the capillaries forviscous and drop wise flows respectively. Bulb number 10 holds liquidin and limb number 11 sucks out from bulb number 10, and number 12controls pressure of bulb number 9.

numbers 3, 2, and 1 with air tight stoppers. Joint number 4 wasfitted with movable L shaped hollow stopper fitted syringe; thestopper and syringe were connected via a silicon tube of 1.5-mminner diameter and joint number 1 remains open. A plunger ispushed back to suck a liquid up from bulb numbers 10 to 5 viabulb numbers 9 and 6, and then the stopper from joint number3 is withdrawn for the liquid to flow back from bulb number9 to 10. It evacuates bulb number 9 for pressure control, anda syringe stopper from joint number 4 is withdrawn, for liquidto flow back to bulb number 10. A capillary of bulb number 6is fused with bulb number 9, for an unhindered viscous flowfor a liquid to flow back from bulb number 6 to bulb number10 via number 9. The flow time is measured within upper andlower marks of bulb number 6; the instrument is mounted onstainless steel stand and calibrated with water at ±0.05 ◦C control,read with Beckman thermometer. For subsequent solutions, theprevious liquid is sucked out via limb number 11 with suctionpump with socket number 5. For sucking out, joints 2, 3, and 4are blocked and number 1 remains open, and bulb number 10 isevacuated. Then bulb numbers 10, 9, 8, 7, 6, and 5 are rinsed withthe next subsequent liquid, and t is measured for ‘n’ number ofsamples.

Surface tensions

Liquid from bulb number 10 is sucked to bulb numbers 9, 8, and 7,by blocking the joint numbers 4, 3, and 1 with air tight stoppers andjoint number 2 is fitted with a syringe stopper. The joint number 1remains open; a plunger is pushed back to suck up the liquid frombulb numbers 10 to 7 via bulb numbers 9 and 8, respectively. Thestoppers from joint number 3 are withdrawn for the liquid frombulb numbers 9 to 10 to evacuate bulb number 9 for pressure.Limb number 12 allows air pressure to push a liquid down frombulb number 9 to 10; the syringe stopper is withdrawn from jointnumber 2, for downward flow of liquid. A capillary of bulb number8 is extended to bulb 9 and remains hanging by 3–4 mm, for dropformation and detachment. The drops are counted within theupper and lower marks of bulb number 8; after measurements, theliquid is sucked out via limb number 11 using a suction pump withsocket number 5. For this, the joints 2, 3, and 4 are blocked, andnumber 1 remains open for suction to evacuate bulb number 10.

Critical overview

Since inception,[8 – 12] no single instrument has been used for both tand n simultaneously. Singh[26] has studied specific viscosities andWilhelmy, duNouy, Jaeger, Sugden, and Ferguson have studiedcapillary action but Hakines and Brown emphasized surface forcewith individual instruments. An error analysis was conducted andhas shown to build credibility in this device.

Result

Density (ρ) measurements are explained elsewhere; viscosities (η)and surface tension (γ ) were calculated from flow times and dropnumbers respectively with the usual equations.

Literature and experimental data are given in Table 1 andregression constants in Table 2. A contribution of –CH3, groupsfor η and γ data are analyzed as under.

x – CH3 = MU − U, x(2 – CH3) = DMU − U, x(3 – CH3) = TMU − U (1)

x – CH3 = DMU − MU, x(3 – CH3) = TMU − MU, x(2 – CH3)

= TMU − DMU (2)

The 2–CH3 and 3–CH3 infer contributions of 2 and 3–CH3

groups and x = η or γ ; the data are given in Table 2. Regressionconstants are depicted in Figs 2–5.

Discussion

The γ 0 values for ureas (Table 2) are as DMU > U > MU, withhigher cohesive forces for DMU. Hence stronger hydrophobicinteractions produce higher cohesive forces for N-ureas due toeffective caging of bulk water. It develops stronger integratedmolecular forces among ureas with stronger adhesion withglass. Thus –CH3 groups in association with N+ and >CO−

develop stronger heteromolecular forces with higher surfaceforces. The γ 0 values of MU decrease at each temperature. Itsasymmetric structure due to –CH3 unbalances the surface forcesbut γ 0 values for DMU are higher due to symmetric structure(Table 2). The U and MU with comparatively stronger hydrophilicinteractions have lower γ 0 values with weaker surface forces(Table 1).

www.interscience.wiley.com/journal/sia Copyright c© 2008 John Wiley & Sons, Ltd. Surf. Interface Anal. 2008; 40: 15–21

17

Survismeter for simultaneous viscosity and surface tension

Table 1. Surface tensions (γ /10−3 N m−1) and viscosities (η±4.4×10−5 N s m−2) with literature � = Exp. – Lit. The exp. and lit. are for experimentaland literature, respectively

Measurements with survismeter

Surface tension Exp. – Lit. Viscosity Exp. – Lit

Systems T (K) Lit. Exp. � Lit. Exp. �

Methanol 298.15 22.28 22.31 0.03 0.547 0.549 0.002

293.15 22.55 22.48 0.07 – – –

Ethanol 293.15 22.40 22.46 0.06 1.060 1.061 0.001

Glycerol 298.15 64.00 64.03 0.03 1.490 1.489 −0.001

Glycerol 293.15 63.40 – – 1.490 – –

Ethyl acetate 298.15 23.15 23.17 0.02 0.441 0.443 0.002

n-hexane 298.15 17.90 17.86 −0.04 1.790 1.794 0.004

Diethyl ether 293.15 72.8 72.768 −0.032 0.233 0.2332 0.002

Chloroform 293.15 27.1 27.101 0.001 0.58 0.5810 0.001

Benzene 293.15 28.9 28.889 −0.011 0.652 0.6518 −0.0002

CCl4 293.15 27.0 27.002 0.002 0.969 0.9691 0.0001

Formic acid 293.15 31.40 31.44 0.04 1.465 1.4649 −0.0001

The literature values are extracted from Refs. [2,4 -6].

Table 2. Contribution of methyl group calculated from [(N-ureas) − (urea)]/n; n represents number of –CH3 groups -

For ρ0

T (K) MU − U DMU − U TMU − U DMU − MU TMU − MU TMU − DMU

293.15 0.00000 −0.00005 −0.00003 −0.00010 −0.00003 0.00000

298.15 0.00000 −0.00015 −0.00015 −0.00030 −0.00020 −0.00015

303.15 −0.00030 −0.00005 −0.00005 0.00020 −0.00003 −0.00005

For γ 0

293.15 −0.90 0.42 1.31 1.75 2.05 2.20

298.15 −0.95 0.38 1.29 1.72 2.03 2.19

303.15 −1.28 0.49 1.69 2.26 2.68 2.90

For [η]

293.15 0.2300 0.6363 0.7819 1.0426 0.9659 0.9276

298.15 −0.4261 0.8778 1.6363 2.1817 2.3237 2.3900

303.15 −0.0523 1.2200 1.8698 2.4932 2.5105 2.5192

Trends for Ss are as 293.15 > 298.15 > 303.15 for U;293.15 > 303.15 > 298.15 for MU and 298.15 > 293.15> 303.15 for DMU which illustrate the temperature ef-fects of surface forces on hydrogen bonding with compo-sitions. Thus U produces stronger structure breaking abilityat 293.15 K than at 298.15 and 303.15, while the MU, astronger structure breaking at 293.15 K than at 303.15 and298.15 K and DMU with similar structure breaking actions ateach temperature.

Comparatively at a temperature of 298.15 K, stronger structurebreaking actions occurs than at 293.15 and 303.15 K. The [η] forureas are as DMU > MU > U, DMU > U > MU, and DMU >

U > MU at 293.15, 298.15, and 303.15 K, respectively (Table 2).The DMU, with a larger size, produces higher hydrodynamicvolume and stronger torque due to a cage of bulk water aroundit. The large-sized molecules show higher [η] values but with

a decrease in [η] values, the D values increase. Negative andpositive [η] values infer weaker and stronger solute–solventinteractions. The higher [η] values infer urea as a structurebreaker, which are supported with the Sv values; a temperaturedependence of [η] is related to a structure making or breakingaction.

The γ 0 and [η] values along with their respective slopevalues (Table 1) infer –CH3 groups responsible for struc-ture making. The [η] values for the U, DMU for their0.01–0.09 m solutions elsewhere[21] are different from thanthose of ours which are reported by Singh.[23,26] The tran-sition in values with compositions infers micelle formation;the –CH3 groups increase the γ 0, but an increase in [η]values is noted at 298.15 and 303.15 K (Table 2). Hence thehydrophobic interactions enhance both the surface tensionand viscosities.

Surf. Interface Anal. 2008; 40: 15–21 Copyright c© 2008 John Wiley & Sons, Ltd. www.interscience.wiley.com/journal/sia

18

M. Singh

ρ (288.15 K) = 0.99844 + 0.00261 n -0.00093 n2

ρ (293.15 K) =0.99714 + 0.00226 n -0.00073 n2

ρ (298.15 K) =0.99584 + 0.00191 n -0.00053 n2

ρ (303.15 K) = 0.99454 + 0.00156 n -0.00033 n2

ρ (308.15 K) = 0.99324 + 0.00121 n -0.00013 n2

0.99300

0.99321

0.99342

0.99363

0.99384

0.99405

0.99426

0.99447

0.99468

0.99489

0.99510

0.99531

0.99552

0.99573

0.99594

0.99615

0.99636

0.99657

0.99678

0.99720

0.99741

0.99762

0.99783

0.99804

0.99825

0.99846

0.99867

0.99888

0.99909

0.99930

0.99951

0.99972

0.99993

1.00014

1.00035

0, n = 0, H2N-CO-NH2

n = number of -CH3 groups

ρ, g

cm

-3

288.15 293.15. 298.15. 303.15 308.15K

1 2

Figure 2. Densities 1 × 103 kg m−3 with number n of –CH3 groups in ureas; the coefficient of the equation is obtained on regression of densities with n.

Critical Behavior With n = CH3

But [η] value from 0 to 1 CH3 shows a higher decreaseat lower temperatures but at higher temperatures, a mildincrease (Fig. 3). The [η] shows a linear increase with n thatshows critical points. But γ 0 show stronger decrease from 0to 1 CH3 which further increase from 1 to 2 CH3. At lowtemperatures the n shows higher decrease at CH3 = 1, but

at 308.15 K, a continuous decrease (Fig. 4). The variation in γ 0

with CH3 is an increase at 288.15, but decreases at 293.15,298.15, 303.15, and 308.15 K (Fig. 5). Hence stronger hydrophobicinteraction occur at lower temperature due to CH3 rather thanat comparatively higher temperatures. Comparatively, urea withamino (–NH2) and ketonic (>C O) groups strongly disrupthydrogen-bonded water. Hydrogen bonding centers with ureaare 2(–H–N–H–) + 2(–H–N–H–) + 1(>C–O−) = 5; thus the


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η (288.15 K) = 1.1049 - 0.1076 n + 0.0559 n2

η (293.15 K) = 1.0044 - 0.0651 n + 0.0349 n2

η (298.15 K) = 0.9039 - 0.0226 n + 0.0139 n2

η (303.15 K) = 0.8034 + 0.0198 n - 0.0070 n2

η (308.15 K) = 0.7029 + 0.0623 n - 0.0281 n2

0.6765

0.6890

0.7015

0.7140

0.7265

0.7390

0.7515

0.7640

0.7765

0.7890

0.8015

0.8140

0.8265

0.8390

0.8515

0.8640

0.8765

0.8890

0.9015

0.9140

0.9265

0.9390

0.9515

0.9640

0.9765

0.9890

1.0015

1.0140

1.0265

1.0390

1.0515

1.0640

1.0765

1.0890

1.1015

1.1140

1.1265

0, n = 0, H2N-CO-NH2

n = number of -CH3 groups

η, g

cm

-1 s

-1

2881.5 293.15. 298.15. 303.15 308.15K

1 2

Figure 3. Viscosities 0.1 kg m−1 s−1 with number n of –CH3 groups in ureas; the coefficient of the equation is obtained on regression of viscosities with n.

5 times hydrophilic : 0 times hydrophobic remains effectivefor urea.

Conclusion

The ability of DMU is stronger than MU. DMU acts as a hydrogenbond acceptor. Interactions of N-ureas with water are not asfavorable as of urea, and from urea to N-ureas, the systems movetoward a well-organized state because stable caging occurs dueto greater degree of hydrophobicity. 2–CH3 groups attributesymmetry to the DMU.

Acknowledgements

The author is thankful to University Grant Commission, Govt. ofIndia, for financial support and Dr A.P. Raste, Principal, DBC, forinfrastructural support.

References

[1] Singh M, Chand H, Gupta KC. J. Chem. Biodiv. 2005; 2: 809.[2] Singh M. J. Chem. Sci. 2006; 118(3): 269.[3] Singh M. J. Biochem. Biophys. Methods 2006; 67(2,3): 151.


20

M. Singh

γ (288.15 K) = 73.822 - 1.9805 n + 0.9885 n2

γ (293.15 K) = 73.357 - 1.9220 n + 0.863 n2

γ (298.15 K) = 72.892 - 1.8615 n + 0.7365 n2

γ (303.15 K) = 72.427 - 1.803 n + 0.611 n2

γ (308.15 K) = 71.962 - 1.7425 n + 0.4845 n2

70.20

70.35

70.50

70.65

70.80

70.95

71.10

71.25

71.40

71.55

71.70

71.85

72.00

72.15

72.30

72.45

72.60

72.75

72.90

73.05

73.20

73.35

73.50

73.65

73.80

0, n = 0, H2N-CO-NH2 1 2

n = number of -CH3 methyl groups

γ , d

yne

cm-1

Figure 4. Surface tension, 1 × 10−3 N m−1 with number n of –CH3 groups in ureas; the coefficient of the equation is obtained on regression of surfacetension with n.

[4] Singh M, Kumar Vinod. Int. J. Thermodyn. 2007; 10(3): 121.[5] Singh M. Visionmeter: a novel instrument for teaching chemical

sciences to the visually handicapped. Experimental Techniques, SEM.Blackwell: 2007; (in press).

[6] Singh M. J. Mol. Liq. 2007; 135: 188.[7] Singh M. Bulg. J. Chem. Edu. 2006; 15(6): 426.[8] Franks F. Water, A Comprehensive Treatise, vol. 4. Plenum Press:

New York, 1978.[9] Shellman JA, Schellman C. In The Proteins, vol. 2, Neurath H (ed).

Academic Press: New York, 1974.

[10] Franks F, Desnoyers JE. In Water science review, vol. 1, Franks F (ed).Cambridge University Press: Cambridge, UK, 1985; 171.

[11] Modig K, Kurian E, Prendergast FG, Halle B. Protein Sci. 2003; 12:2768.

[12] Singh M. J. Instrum. Exp. Tech. 2005; 48: 270.[13] Apelblat A, Manzurola E. J. Chem. Thermodyn. 1999; 31: 869.[14] Nelson DL, Cox MM. Lehninger Principles of Biochemistry (3rd edn).

Macmillan Worth Publishers: Hampshire, UK, 2001–2002; 89.[15] Singh M, Kumar A. J. Solution Chem. 2006; 35(4): 587.[16] Singh M. J. Chem. Thermodyn. 2006; 39: 240.


21


2

0.985

-1.059

0.667

-1.125

0.348

-1.192

0.030

-1.258

-0.289

-1.30

-1.08

-0.86

-0.64

-0.42

-0.20

0.02

0.24

0.46

0.68

0.90

1.12

1.34

1.56

1.78

2.00

-1.10 -0.88 -0.66 -0.44 -0.22 0.00 0.22 0.44 0.66 0.88 1.10

variation in surface tension with n

num

ber

of C

H3

grou

p

288.15

293.15

298.15

393.15

308.15 K

Figure 5. Variation in surface tension values with carbon number n.

[17] Lubert S. Biochemistry (4th edn). W.H. Freeman and Company,Butterworth-Heinemann: New York, 1995; 185.

[18] Singh M. Phys. Chem. Liq. 2006; 44(5): 579.[19] Stokes RH, Mills R. Viscosity of electrolytes. Pergmaon press: Oxford,

1964; 31.[20] Einstein A. Ann. Phys. (Leipzig) 190(19): 29.[21] Huggin ML. In Principles of Polymer Chemistry, Flory PJ (ed). Cornel

University Press: Ithaca, 1953; 308.[22] Levine IN. Physical Chemistry (4th edn). Tata McGraw-Hill Publishers:

New Delhi, 1995; 458.

[23] Shoemaker DP, Garland CW, International Student (ed). Experimen-tal in Physical Chemistry. McGraw-Hill Kogakusha: 1967; 249.

[24] Stokes RH, Mills R. Viscosity of Electrolytes. Pergmaon Press: Oxford,1964; 31.

[25] Huggin ML. In Principles of Polymer Chemistry, Flory PJ (ed). CornelUniversity Press: Ithaca, 1953; 308.

[26] Singh M. J. Indian Chem. Soc. 2005; 82: 129.


survismeter for simultaneous viscosity and surface tension study for molecular interactions

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