The Viscosities of Solutions of Chlorides in Certain Solvents - The

A Model for Calculating the Heat Capacity of Aqueous Solutions, with Updated Density and Viscosity Data. Marc Laliberté. Journal of Chemical & Engine...
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T H E VISCOSITIES O F SOLUTIONS O F CHLORIDES IK CERTAIN SOLI-ENTS' FRASK E. DOLIAK w'ni €1. T . RKIfX'OE Department

of

C h e n i i ~ t r i i .I n d i a n a t7nztersitij. RLoominqton, I n d i a n a Rrceii ed Jnniiaril 16, 19%

Recent theoretical studies have aroused new interest in the study of the viscosity of aqueous solutions. The measurements reported in this paper were made during a study of the physical properties of certain solutions that were, in the main, of non-aqueous character. As concerns viscosity the intention was primarily to test equations developed by Jones and his students (4, 5 ) b y attempting to apply them to the viscosities of non-aqueous solutions. MATERIALS

Absolute ethyl alcohol was prepared by repeated treatment with finely divided, freshly dehydrated calcium oxide. Aldehydes and other impurities were removed by the usual methods, and the product was thoroughly fractionated. Precautions were taken to exclude air and moisturc a t all times. The purity of the product was checked by measurements of the refractive index and the density. Only freshly prepared alcohol was used in making up the solutions. Carefully prepared conductivity water was used in making up aqueous solutions or solutions in mixed solvents containing water. Carbon tetrachloride mas purified by the method of McClendon (7). Pure, anhydrous acetic acid and ethyl acetate were further treated to remove water and fractionally distilled. Stannic chloride was prepared by distillation from a mixturc of the hydrate and concentrated sulfuric acid, and precautions were taken to prevent the decomposition of the acid. The anhydrous, liquid stannic chloride was collected in small tubes, which were sealed without allowing the contents to be exposed to the atmosphere. The purity of the product was checked by density measurements. Ferric chloride was prepared by treating thoroughly cleaned and dried pure iron with chlorine. All other salts 1 This paper has been prepaied from a portion of a thesis submitted by Frank E. Dolian to the Faculty of the Graduate School of Indiana University in partial fulfillmcnt of the requirements for the degree of Doctor of Philosophy. T o save space in < printing, represpntative graphical relationships. rather than complete plots of d l data. have frcquentlybeen given

1129

1130

F R A S K E. DOLIAX K I T H H. T. B R I S C O E

were prepared by thoroughly purifying and. carefully dehydrating the purest products obtainable. METHOD

The viscosities of the solutions were nieasured in a modified forni of the Ostwald type of viscometer. Precautions were taken to prevent changes in concentration by evaporation of volatile solvents and contamination with moisture from the air. The rneasurenients were made at E 0 C . & 0 . 0 5 O , and were checked by several determinations for each solution. The viscometers were cleaned and dricd with absolute alcohol and pure dry air. They were standardized with pure water. The time of flow was measured with a stop watch, which wab accurate in readings to 0.1 sec. The density measurements were made in pycnometers of approximately 25-ml. capacity in a constant temperature bath at 25°C. and calculated with reference to pure, carbon dioxide-frw water a t 4°C. Table 1 serves TABLE 1 S t a 71 du r diza t i on o,f

sco m e t c r s

I

VISCOMETER K O .

YOLCME O B L I Q U I D

I

T I M E OF P.4SS.LOE (X'ATEH)

nil.

scconda

6 8 6 6

91.95 85.14 73.48 76.46

PT (DENSITY

X TIME)

91.6782 84.8883 73.2682 76,2340

t o give information coiicerning the visconieters, including total time of passage of liquid, volumes of liquids used, etc. In view of likely percentages of error in the measureinents and in temperature control, the Yiscosity values have been rounded off to four figures. R E S U L T S A N D DISCUSSION

The densities and relative viscosities (with reference t o the viscosity of water as 0.00894 poise a t 25'C.) of solutions of nickel chloride, cobalt chloride, cupric chloride, ferric chloride, cadmium chloride, aluminum chloride, stannic chloride, and mercuric chloride in ethyl alcohol as the solvent are shown in table 2. The viscosities of six of these solutions are plotted against the weight fractions of the solutes in figure 1. The results show that these salts increase the viscosity of ethyl alcohol in the following .order: NiC'12 > hlCl3 > CoClz > CuC12 > FeC13 > CdC1, > SnCL > HgC12. Tlic result.: for solutions of aluminum chloride, nickel chloride, cupric chloridc, and cadniiuin chloride in water are shown in table 3 . The

1131

VISCOSITIES OF SOX-SQI-EOUS SOLUTIOSS

salts iiicreasc the viscosity of water in the following order: XlCl, > NCl, > CuCl, > CdCl?. Except for the aiiomalous behavior of aluminum chloride, the order in which the salts affect the viscosity of each solvent is the same as the order of their molecular weights. The relative effect of aluminum chloride upon the viscosity of ethyl alcohol is greater than TABLE 2 T*iscositics oj' solutions qf s n l l s I'u e t h y l ulcohrrl HgCIl Densit! 25",4"C

Kei $11 t fraction

\$eight fraction

I

0.00000 0.01008 0.01996 0.04164 0 08035 0 84515 0.15020 0 90406 I 0 0122 __~__ SnClr Weight fraction

1

00000 005.50 01095 02172 04266 08242

1

1

I

I

~

COCI?

Density

!$eight

0 0 0 0 0 0

'

I

1

0108 0112 0114 0126 0144 0193

I

~

1

?5",4"C

~

00000 00424 00845 01679 03313 06454,

._

_

0 0 0 0 0 0

Weight fraction

, Densit>-

Weight fraction

'I

25":4TC.

,

0.78641 0.78920 0.79173 0.79739 0.80832

_

-

\\eight

___

0 78523 0 0108 0 78888 0 0111 0 79276 0 0113 0 79994 0 0119 0 81462 0 0132 0 84139 0 0162

Deri-it!

fraction

25'/4"C

0 OOLOO (1 00192 0 00382 0 00757 0 01492

0 0 0 0 0

-

I)

-~

78533 0 0110 78849 0 0112 79145 0 0114 798111 0.0120 81012 0 0131 __

-

CUCl

______

0 00000 0,00393 0.00784 0.01557 0.03072

_

78545 0 0107 787951 0 0108 79083 0.0111 79583 0 0115 80648 0 0121 828081 0 0137

__

CdCI.

'I

_

xic1

Densit\

78545 1 0 0107 I 0 00000 78913 1 0 0109 0 00515 79213 0 0110 0 01024 79890 1 0 0113 0 02030 81356 0.0119 0 03986 84217 0 0132 0 07719

0 0 0 0 0 0

__

_fraction _ _ _ _1 25"/4"C _

25'/4'C

Densit!

Raight frdction

r,

0.00000 I 0 7853OI 0 0 00380 I 0 78860 0 0 00757 0.791611 0 0.01501 0 79798 0 0 02955 1 0 81075 0 0 05734 0 83563 0 __

- ____

______ 0 0 0 0 0 0

Derisiti

25" 4°C

_ _ _ _ _ _ _ _ _ _ .

~

~~~

FeCl I

AlCli

_ ~ __ _ ____---___

Density

25"!4"C:.

I

0.0109 0 0111 0 0111 0 0115 0 0119

'

0.00000 0 00526 0 01050 0 02028 0 01131 0 07957

-~

~

'I

-I

~

I

0 0 0 0 0 0

78572 0.0108 78935 79173~0 0112 80058 0 0117 81375 84549 0 0144

-___

_.___

___ - -

-

one might predic from a consideration of molecular I\ c.ight s alone, and in x-atcr the effect is still further pronouncrd. This bchar-iur may be the result of the reaction of aluriiiiiuni chloride with tht. solwilts t o form large numbers of ions in the solutions. This explanation \~-ouldbe in keeping with hlcleod's (8) principle that the formation of ions leads to a decrease in the free space and to an increase in the viscosity. That the effect is

1132

F l l A N K E. DOLIAK W I T H H. T. BRISCOE

caused by ions appears to be substantiated, at least in part, by a comparison of the results in alcoholic and aqueous solutions. If the change in viscosity, or the viscosity increment, Aq, is plotted against the weight fraction of the same solute in different solvents, the curves are found to rise more steeply in every case for the solutions in ethyl alcohol than they do for the aqueous solutions. This might be predicted from the interionic attraction theory. The "tightening" effect and consequent increase in viscosity should probably be less in water than in alcohol, because of the great difference in the dielectric constants of the two liquids. The viscosity increment- weight fraction curves for solutions of several salts in

-

TABLE 3 T'iscositics of aqueous solutions o j certain salts ~

~

II

AlClP Weight fraction

0.00000 0.00230 0.00470 0.00930 0.01840 0.03610 _____ -_________

I

~

,

Densit\ 25'/4'C

0.99704 0 99949 1.00157 1.00585 1.01536 1,03297 -

CdCl? Xeight fraction

n

0 0089 0.0091 0 0092 0 0095 0 0101 0.0113

1

0 0 0 0 0 0

, 1

00000 00190 00378 00760 01500 02960

- -

i

Density 25"/4"C.

7 .

0.00000 0.00-120 0.00830 0.01650 0.03250 0 06350

0.99704 1 ,00097 1,00479 1.01161 1.02726 1.0 5 6 G

,

0 99704 0.99879 1 00047 1 00284 1 01055 i 02306

11

1 1

1

__. __ . ________________

0 0089 0.0090 0 0090 0 0091 0 0092 0 0095

NlCl

CUCI? Weight fraction

Densit\ 25'/4'C

_-

____

0.0089 0 0091 0 0092 0.0094 0.0098 0 0108

Weight fraction

Densit> 250/4"C.

0 00000 00290 0 00570 0 01140 0 02250 0.04410

0 99704

I

7

-

0 0089 0 0091

n

1

1 00270 1 00748

1.Ill848 1 03974

___-

'

0 0 0 0

0092 0093 0097 0103

methyl alcohol were found (in work not reported here) to lie in all caws between the curves for ethyl alcohol and water. The effect of a solute upon the viscosity of a solvent has also been explained frequently as the result of the action of particles of the dissolved substance upon the association of solvent molecules. I n an effort to dctermine the effect of a change of solvent upon the viscosity of a solution of aluminum chloride, the viscosities of solutions in different mixtures of ethyl alcohol and hvater were investigated. These two solvents were selected because the viscosity-mole fraction curve for these two liquids shows a very decided maximum. This maximum has long been recognized and is generally attributed to "further association and eventually complex

VISCOSITIES O F NOK-AQUEOCS SOLUTIOXS

1133

formation" by the two liquids. This is in accordance with the thcory of Dunstan and Thole (2), although it is sometimes stated that such maxima arc cauaed by dissociation of "associated complexes" or of molecules. The viscosities of solutions of aluminum chloride in different mixtures of ethyl alcohol and water are given in table 4 and shown graphically in figure 2. If the theory of Dunstan and Thole is correct, it appears that the addition of aluminum chloride to a mixture of ethyl alcohol and water leads to an increase in the association of t h r two liquids, since the solute

i

i'

-1

i

i

i: 061 OO? 003 @D? 005 I">&CO- 008 009 O!O 0 ' 1

n:F;r.i.-r

rP?C-l3h

FIG.

3. SPL~TF

1

12Ic;. 1. Thc viscosities of solution of salts in et,hyl alcohol. I, Si('12; 11, .41("la; 111. ("rd'l?; IV, FeC13; V, SnCI,; VI, HgCl2. FIG,2 . Viscosities of solutions of aluminum chloride in mixtures of ethyl alcohol and water. The concentrations of aluminum chloride are (in moles per liter) 0.0000, 0.0937, 0.1871, and 0.3718, reading from t'he bottom curve t o the one a t the t,op.

increases the viscosity of the mixture corresponding to the maximum more than it does any other mixture of the two solvents. I t is difficult to rsplain these results purely upon the basis of ionic effects. Minima in viscosity-concentration curves (1, 9) have been explained by assuming that one substance causes the dissociation of associated niolecules of the other. Results of this character are shown by our data for mixtures of ethyl alcohol and carbon tetrachloride (table 5 and figure 3). The position of the minimum in the region of dilute solutions of ethyl alcohol carries out thc idea that dissociation is more complete at high diliition.

1131

F R A S K E. DOLIAK WITH H. T. BRISCOE

SOLYEST COMPOSITIOh ( M O L E FRATTIOX OF H.0)

AICI, C O S C E S T R A I I O S I S MOLY’i PER LITEI:

‘ISCOSITY

0,147

0 .0000 0.1874 0.3748

0.0129 0.0180 0.0242

0 302

0 ,0000 0 1874 0 37ih

0.0153 0.0206 0 0276

0.449

0 . 000(1 0.0937 0.1874 0.3748

0.0182 0.0209 0.0226 0.0306

0.685

0.0000 0.0937 0.1874 0 3748

0.0228 0.0255 0.0269 0.03-12

0 830

0 0000 0.0937 0.187.4 0.3718

0.0227 0.0249 0.0262 0.0315

0 929

0 0000

0,0150 0.0165 0.0172 0.0205

0.0937 0.1874 0.3748

TABIX 5 I.iscosities of’ethyl alcohol-carbon t r t m c h l o r i d c solutions COXCENTRATIOS (MOLE FRACTION O F ~.__

__

cch) ~

.- ..

-

__-

VISCOSITT

0.000 (C2Hc0€€)

0.0107

0.063 0.131

0.0107 0.0107

0.20.5 0.330

0.0105 0.0102

0.473 0.642 0,843 0.917 1.000 (CCla)

0,0098 0,0094 0 . 0089

0.0089 0.0092

V I S C O S I T I E S O F h-ON-A4QCEOVS SOLUTIOXS

1135

Jones and Talley and Jones and Dole (4,5 ) have proposed an equation,

to express the relation between the relative visco4ty and the concentration, c, in moles per liter. This equation can be transformed into

-q -

1

770

di Ii

=

A i B&

I

i

i

I

I

I

, %

‘:LE

-QP‘

0

.Q 9 l V

102

--7ab:*LI)QlDf

FIG.3

9

v%

FIG. 4

FIG.3. T h e viscosities of iiiixtures of ethyl alroliol and carbon tetrachloride FIG.4. The Falkenhagen equation. 0 , S i C l z ; 0 , A1Cl3; 0 , FeCI3 77-

Whcn

-1

_ 770 _

4

is plotted against di, the result is a straight line, whose inter-

cept on the vertical axis is A and whose slope is B. -9 - 1

The values of ‘

d C

!and

6for different solutions of

salts in ethyl

alcohol are given in table 6. The results for three of these solutions are shown in figure 4. A11 the curves are similar to one or the other of the two types shown in this figure, and, in order to save space, those given have been selected as typical cases. Straight lines passing through, or approximately through, the zero point on the vertical axis were obtained for solutions of cobalt chloride, ferric chloride, stannic chloride, cupric chloride,

1136

FRANK E. D O L I h N WITH H. T. BRISCOE

mercuric chloride, and cadmium chloride in ethyl alcohol. For these curves the value of the constant A is approximately zero, and the relation TBBLE 6 Viscosities of solutions of certain salts in ethyl alcohol

NiC12 in C2HbOI-I

0.0000 0.0117 0.0233 0.0466 0.0932

(70 =

0.0110)

indet . 0.134 0.231 0.411 0.695

0.0110 0.0112 0.0114 0.0120 0.0134

HgCL in C z H 5 0 H ( q 0 = 0.0107)

00.00 10.82 15.26 21.60 30.53

0.0000 0.0313 0.0625 0.1250 0.2500 0.5000

0.0107

indet.

00.00

0.0110 0.0111

0 086 0.098

25.00 35.36

0.0122

0.188

I

70.71

___~_

.____

FeC13 in C Z H ~ O H ( 7 0 = 0.0107)

0.00000 0.02059 0.04118 0.08235 0.1647 0 3294

0.0107 0.0109 0.0111

1

0.0137

indet.

0.00000

i 0.111 1

::::::I

~

SnClr in C 2 H b 0 H(q0 = 0.0107)

~,

~

0.0109 0.0110 0.0113 0.0119 0 0132

0.190 0.258 0.335 0.486

40.58 1 0.13319 57.40 I ' 0 26638 ___. pllp -_-_ __ -

indet. 0.171 0.132 0.202 0.307 0.463

00.00 12.9 18.2 25.8 36.5 51.6

1

~

CdClz in C Z H ~ O H ( 7 0 = 0.0110)

~

SnC14 in CzHbOH (va

=

0.00439) ___..

0 .oooo 0.0169 0.0339 0.0677 0.1354

0.12.50 0.5000

I 0.0109 j indet.

I

0.0111 0.0111 0.0115 0.0119

0.0117 0.0144

!

1

1 ~

0.098 0.089 0.186 0.251

0.231 0.478

1

00.00 13.00 18.41 26.02 36.80

1

ll ~

0.0000 0.0394 0.0789 0.1577 0.3154 0.6308

0.0044 0.0045 0.0047 0.0050 0.0055 , 0.0072

indet. 0.139 0.224 0.349 0.438 0.811

-

00.00 19.87 28.09 39.71 56.16 79.42

35.36 70.71

between viscosity and concentration is expressed for these solutions by the equation --' - 1

+Bc

170

The positive value of B indicates the positive slopes of the curves.

1137

VISCOSITIES O F NON-AQUEOUS SOLUTIONS

The curves for aluminum chloride and nickel chloride in ethyl alcohol differ from those of the other salts in that the straight lines connecting the points pass below the zero of the vertical axis. This means that for these solutions the value of the constant A is negative. The meaning of the constants A and B has been considered by Falkenhagen and Vernon (3), Jones and Dole (4), and Jones and Talley ( 5 ) . Fallienhagen and TTernoncompute A for aqueous solutions of a uni-univalent salt by means of the following equation:

1 in which 770 and Do are the absolute viscosity and dielectric constant of water a t temperature T , and Zl and Z2 represent the equivalent conductances TABLE 7 Viscosities 01solutions of HgCL i n acetic acid W E I G H T FRACTION

0.00000 0.00550 0.01100 0.02200

DEXSITT

25"/4"C.

1.04465 1.04929 1.05429 1.06344

t)

I

0.0117 0.0117 0.0118 0.0120

Viscosities of solutions of SnC14 in ethyl acetate I W E I G H T FRACTIOK

0 .00000 0.01110 0.02220 0.04440 0.08570 0.16090

t)

0.89374 0.90208 0.90997 0.92565 0.95853 1.02197

I

I

0,0044 0.0045 0.0017 0.0050 0.0055 0.0072

of the two ions a t zero concentrations. This equation shows that the value of A is determined largely by the different factors involved in the Debye-Huckel theory. For a given salt in a given solvent, A depends upon the valence type of the salt, upon the dielectric constant of the solvent, and upon the mobilities of the ions of the salt. Of the factors that determine B, very little is known at the present time, but results obtained (2) with aqueous solutions of sucrose and urea indicate that the value of this constant depends upon factors that involve relationships between mo!ecules of solute and solvent, rather than ions. The results obtained in this investigation for a majority of the salts in ethyl alcohol show that the conditions determining A are not of great

1138

FRAXK E. DOLIAK WITH H. T. BRISCOE

significance, or possibly that the effects of different factors cancel each other. The negative values of A for solutions of aluminum chloride and nickel chloride in ethyl alcohol must arise, according to the equation of Falkenhagen and Yernon, from very great differences in the mobilities of the ions present in the solution. Such a condition might be expected in solutions coiitaiiiing highly complex solvated metallic ions and simple anions. Although they are somewhat apart from the other results reported in this papc'r, we have added in table i the viscosities of solutions of mercuric chloride in glacial acetic acid and stannic chloride in ethyl acetate. So far as we know the viscosities of these solutions have not been reported previously. The results for stannic chloride in ethyl acetate show a sharp increase in slope a t higher concentrations, indicating a probable maximum and complex formation. This solution gives a negative value for A and a positive value for B in the Falkeiihagen and Vernon equation. SUMMAH1'

The viscosities arid densities of solutions of eight metallic (ahlorides in ethyl alcohol, of solutions of four of the same salts in water, of aluminum chloride in mixtures of ethyl alcohol and water, of mercuric chloride in acetic acid, of stannic chloride in ethyl acetatr, and of carbon tetrachloride in ethyl alcohol are reported. All of the salts studied increased the viscosity of the solvent, and the viscosity increase is greater for alcohol than for water. Aluminum chloride increases the viscosity of the solution of ethyl alcohol and water having the maximum viscosity to a greater extent than it does the viscosity of any other niisture of these two liquids. The viscosity-concentration curve for mixtures of ethyl alcohol and carbon tetrachloride has been shown to give a minimum. Results for the solutions in ethyl alcohol have been discussed in the light of different theories, especially the Jones and Dole equation involving the viscosity of solutioiis of electrolytes. IIEFEHESC'ES (1) BAKER:J. Chem. Yoc. 101, 1416 (1912). (2) DUNSTASAND THOLE: The Viscosity of Liquids. Longmans, Green and Co., London (1917). (3) F A L K E N H A G E N AND V E R N O N : Physik z 33, 140 (1932); Phil. ?\fag. 171 14, 537 (1932). (4) JONES AND DOLE:J. Am. Chem. Soc 61,2950 (1929). (5) JOXES AND TALLEY: J. Am. Chem. Roc. 66,624 (1933). (6) JONES AND V E U E Y :Am. Chem. J . 37, 405 (1906). (7) MCCLENDON: J. Biol. Chem. 60, 295 (1924). (8) MCLEOD:Trans. Faraday Roc. 1 9 , 6 (1923); 21, 15 (1925) (9) WAGNER: Z. physik. Chem. 76, 367 (1911).