Thermodynamic Functions of Activation for Viscous Flow in Electrolyto-Water-Organic Solvent Systems. Part I. NaI Solutions in Mixtures of Water with Isopropanol and Tert-butanol

A C T A U N I V E R S I T A T I S L O D Z I E N S I S FOLI A C H I M I C A B, 1988

Anna Ka c p e r s k a * , S t e f a n i a Taniewska-Osiriska* T H E R M O D Y N A M I C F U N C T I O N S OF A C T I V A T I O N FOR V I S C O U S FLOW

IN E L E C T R O L Y T E - W A T E R - O R G A N I C S O L V ENT S Y S T E M S PART I. Nal S O L U T I O N S IN M I X T U R E S OF WATER

WI TH IS OP ROP AN OL AND T E R T - B U T A N O L

F u n c t i o n s of a c t i v a t i o n for vi sc o u s flow A H * , A S * , and AG* h a ve be en c a l c u l a t e d for the s y s t e m s N a l - w a t e r - i s o p r o p a n o l in the ra nge of t e m p e r a t u r e s 2 8 8 . 1 5 - 3 1 3 . 1 5 K and N a l - w a t e r - t e r t - -b ut ano l in the range of t e m p e r a t u r e s 2 9 9 . 1 5 - 3 1 3 . 1 5 K. The c a l ­ c u l a t i o n s were m a de for Nal s o l u t i o n s with c o n c e n t r a t i o n s 0.5,

1.0 and 2.0 m o le s of salt per 100 m o le s of the s o l v e n t on the ba sis of our p r e v i o u s v i s c o s i t y data. The re su l t s o b t a i n e d have been i n t e r p r e t e d from the point of view of al co h o l e f fe ct on the w a te r s t r u c t u r e and that of Nal on a mixed s o lv e n t structure.

I n t r o d u c t i o n

In our ea rl i e r p a pe rs [1-3] we r e p o r t e d the r e s u l t s of v i s c osi - m e t r i c i n v e s t i g a t i o n s for the systems: N a l - w a t e r - i s o p r o p a n o l at 288.15, 298.15, 313.15 K and N a l - w a t e r - t e r t - b u t a n o l at 299.15, 308.15 and 313.15 K. M a k i n g use of these data and m e a s u r e d d e n s i t i e s of N a l - w a t e r - t e r t - b u t a n o l s y s t e m at 308.15 and 3 13. 15 K, put in T abl e 2, the t h e r m o d y n a m i c f u n c t i o n s of a c t i v a t i o n of v i s c o u s flow have be en c a l c u l a t e d for b o th i n v e s t i g a t e d systems. R e s u l t s and D i s c u s s i o n As it is k n o w n the t e m p e r a t u r e d e p e n d e n c e of l i qu id v i s c o s i t y may be e x p r e s s e d by E y r i n g ’s e q u a t i o n [4]: * D e p a r t m e n t of P h i s ica l C h e m ist ry , I n s t i t u t e of C h e m i s t r y , U n i ­ v e r s ity of Łódź. [6ll

T a b l e 1 fOO M e an m o la r vo lumes, V(cm mol ), of Nal s o l u t i o n s in w a t e r - i s o p r o p a n o l m i x t u r e s

at 288.15, 298. 15 and 313.15 K c a l c u l a t e d on the b a se of d e n s i t y data from pa per [ l ] ; c - c o n c e n t r a t i o n of Nal in m o l e s per 100 m o l e s of m i x e d solv ent

c = 0 c = 0.5 c = 1.0 c = 2.0 X IPAX 288 15 298 15 313 15 288 15 298 15 313 15 288 15 298 15 313 15 288. 15 298 15 313 15 0 18 03 20 08 18 16 18 11 18 15 18 25 18 20 -18 25 18 35 18 36 18 42 18 54 1 .5 18 82 18 86 18 95 18 90 18 94 19 05 18 98 19 03 18 52 19 14 19 21 19 33 5 .0 20 58 20 65 20 80 20 70 20 73 20 89 20 73 20 82 20 98 20 90 20 99 21 16 7 .5 21 82 21 95 22 15 21 91 22 03 22 23 22 00 22 11 22 32 22 16 22 28 22 50 10 .0 23 14 23 29 23 54 23 22 23 37 23 62 23 30 23 45 23 71 23 47 23 62 23 87 15 .0 25 .87 26 07 26 41 25 95 26 14 26 48 26 03 26 22 26 55 26 18 26 37 26 64 20 .0 28 70 28 95 29 34 28 76 29 00 29 39 28 83 29 07 29 43 28 94 29 16 29 56 25 .0 31 57 31 83 32 29 31 61 31 87 32 32 31 66 31 92 32 37 31 32 00 32 44 30 .0 34 45 34 77 35 27 34 47 34 79 35 28 34 51 34 83 35 31 34 57 34 88 35 35 40 .0 40 26 40 67 41 27 40 25 40 67 41 26 40 26 40 64 41 24 40 25 40 66 41 24 50 .0 46 11 46 62 47 36 46 08 46 57 47 30 46 04 46 51 47 26 45 98 46 45 47 16 60 .0 52 04 52 60 53 46 51 96 52 52 53 36 51 91 52 46 53 28 51 79 52 28 53 12 70 .0 57 .99 58 65 59 60 57 89 58 52 59 46 57 78 58 42 59 35 57 60 58 21 59 13 80 .0 63 .99 64 71 65 78 63 84 64 57 65 60 63 71 64 41 65 44 63 45 64 12 65 13 85 .0 67 00 67 75 68 88 66 82 67 57 68 66 66 66 67 38 68 48 66 36 67 07 68 13 90 .0 69 98 70 83 72 08 69 79 70 60 71 74 69 61 70 38 71 62 69 29 70 05 71 .22 92 . 5 71 53 72 33 73 56 71 33 72 10 73 30 71 12 71 88 73 13 70 72 71 45 72 62 95 .0 73 07 73 87 75 14 72 85 73 62 74 86 72 .65 73 .39 74 63 72 27 73 .01 74 .18 97 .5 74' 61 75 42 76 71 74 39 75 16 76 43 74 15 74 .93 76 20 73 74 74 .47 75 .71 100 .0 75 19 76 91 78 25 75 92 76 07 77 99 75 64 76 .39 77 72 75 17 75 90 77 .21 An na K a c p e r s k a , S t e f a n i a T a n i e w s k a -O s i ń s k a

w h er e h is P l a n c k ’s co nstant, V is m o la r volu me of so lution, N is A v o g a d r o ’s n u mb er and A G *, A H * and A S * are the free e nergy, e n t h a l p y and e n t r o p y of a c t i vat io n, r e s p e ct iv el y. E q u a t i o n (1) can be b r o u ght to (2) by i n c l u d i n g A S * and V to c o n s t a n t A

f) = A . exp (2)

The form of e q u a t i o n (2) is e s s e n t i a l l y id en tic al wi th A r r h e n i u s ’ e q u a t i o n [4] so AH * can be e q u a t e d to E v ^g (e ne rgy of ac t i v a t i o n ) from A r r h e n i u s ’ eq uation. E q u a t i o n (2) lets us c a l c u l a t e mean enthalpy of a c t i v a t i o n of vi sc o u s flow (energy of ac t i v a t i o n ) , Â R * , from the f u n c t i o n In h = f ( 1 / T ). The valu es of free e n er gy of a c t i v a t i o n have been c a l c u l a t e d by m e an s of e q u a t i o n (1) in w h ic h V is a me a n m o la r volu me of the solution.

Ta ble 1 shows the c a l c u l a t e d v a lu es of m e an m o l a r v o lu me of Nal s o l u t i o n s in m i x t u r e s of wa ter with is o p r o p a n o l (IPA) and in Table 2 there are valu es for Nal s o l u t i o n in the m i x t u r e s of w a te r with t e r t - b u t a n o l (TBA) in all t e m p e r a t u r e s i n ve sti ga te d. The c a l c u l a t e d v a lu es AG*, ÂTï* and TAS* for the m i x t u r e s of w a te r with IPA and TBA and also for Nal s o l u t i o n s in these sy st e m s are p r e s e n t e d in T a bl es 3-6.

T a b l e 2 De ns iti es , p ( g . c m ' ’5), and mean m o la r volumes, V i c m ^ m o l ' 1 ), of Nal s o l u t i o n s in w a t e r - t e r t - b u t a n o l m i x t u r e s at 299.15, 308.15 and 313.15 K c - Nal c o n c e n t r a t i o n in m o le s per 100 m o le s of the m i xe d

solvent. De ns i t y data at 299.15 K are taken from p a pe r [2]

c = 0 c = 0.5 c = 1.0 c = .0 V _Po V _P V _P V _P V 1 2 3 4 5 6 7 8 9 299.15 K 0 0.99681 18.07 1.0279 18.16 1.0585 18.25 1.1172 18.44 5 0.9704 21.46 0.99 62 21.55 1.0215 21.63 1.0702 21.82 10 0.9420 25.08 0.9645 25.15 0.9866 25.21 1.0283 25.38

Ta ble 2 (contd) 1 2 3 4 5 6 7 8 9 20 0.8964 32.62 0.9139 32.65 0.9312 32.68 0.96 54 32.74 30 0.8654 40.27 0.8799 40.26 0.8940 40.25 0.92 23 40.23 40 0.8434 47.94 0.8553 47.94 0.8677 47.88 0.8911 47.81 50 0.8260 55.77 0.8367 55.68 0.8469 55.61 0.86 75 55.45 60 0.8126 63.60 0.8222 63.45 0.8313 63.34 0.84 96 63.10 70 0.8018 71.45 0.8104 71.26 0.8183 71 .13 0.83 47 70.81 BO 0.7931 79.31 0.8007 79.10 0.8083 78.89 0.82 35 78.46 90 0.7854 87.23 0.7930 86.91 0.8001 86.64 0.81 B4 85.67 95 0.7822 91.18 0.78 92 90.86 0.7961 90.56 0.81 00 89.95 100 0.7799 95.04 - - - -308.15 0 0.99406 18.12 1.0249 18.22 1.0550 18.31 1.1135 18.50 5 0.9650 21.58 0.9910 21.66 1.0162 21.75 1.0647 21.93 10 0.9354 25.26 0.9566 25.36 0.9785 25.42 1.0202 25.59 20 0 .8901 32.85 0.90 55 32.95 0.92 46 32.91 0.95 58 33.06 30 0.8608 40.48 0.874B 40.49 0.8B85 40.50 0.91 62 40.50 40 0.8348 48.46 0.8469 48.42 0.85 90 48.36 0.8819 48.31 50 0.8176 55.77 0.8283 56.24 0.8387 56.16 0.85 87 56.02 60 0 .8042 64.26 - - 0.8227 64.00 0.8414 63.71 70 0.7930 72.25 0.8015 72.06 0.8099 71 .87 0.82 62 71.54 80 0.7842 80.21 0.7928 79.89 0.79 95 79.75 0.81 47 79.30 90 0.7765 88.23 0.7837 87.94 0.7909 87.65 0.8054 87.05 95 0.7732 92.24 0.7802 91 .91 0.78 72 91.59 0.80 06 91.01 100 0.7711 96.13 0.7764 95.96 - - - -313.15 0 0.99 224 18.16 1.0230 18.25 1.0525 18.36 1.1110 18.54 5 0.9626 21.63 0.9883 21.72 1.0132 21.81 1.0623 21.98 10 0.9314 25.37 0.9531 25.45 0 . 97 46 25.53 1.0168 25.67 20 0.8846 33.05 0.9017 33.09 0.91 85 33.13 0.95 22 33.19 30 0.85 45 40.78 0.8686 40.78 0.88 24 40.78 0.91 00 40.77 40 0.8321 48.62 0.8438 48.59 0.85 64 48.51 0.8792 ' 48:46 50 0.8132 56.65 0.82 34 56.58 0.8341 56.47 0.85 44 56.30 60 0.7991 64.67 0.8087 64.51 0.81 82 64.35 0.83 66 64.08 70 0.7878 72.72 0.7965 72.51 0.8051 72.30 0.82 14 71.96 80 0.7787 80.78 0.7865 80.53 0.79 40 80.31 0.80 96 79.80 1

Table 2 (contd) 1 2 3 4 5 6 7 8 9 90 95 100 0.77 16 0.76 78 0.76 48 88.79 92.89 96.92 0.7785 0.77 43 0.77 16 88.53 92.61 96.55 0 . 7856 0.78 15 88.24 92.25 0.7996 0.7954 87.68 91 .60 T a b l e 3

F u n c t i o n s of a c t i v a t i o n for vi sc ous flow in w a t e r - i s o p r o p a n o l system- A * * - m e an ener gy of a c t i v a t i o n in the range of tempera tu re s: 2 8 8. 15 - 313.15 K, A G * - free e n er gy of ac ti vat io n, AS * - e n t r o p y

of a c t i v a t i o n for vi sc ous flow

x_aX AH * A G * , k J m o l '1 TAS* , kJmol 1 kJmo l'* 288 .15 298 . 15 313 .15 288 .15 298 . 15 313 . 15 0 ' 16 79 9 .44 9 .43 8 .83 7 .35 7 . 36 7 96 1 .5 19 .49 10 . 19 9 .82 9 .42 9 .30 9 .67 10 .07 5 .0 24 .46 11 .65 11 17 10 .60 12 .81 13 30 13 .86 10 .0 29 .19 12 .93 12 34 11 59 16 . 26 16 .84 17 60 15 .0 30 15 13 59 12 99 12 24 16 .56 17 .17 17 91 20 .0 29 38 13 .93 13 35 12 69 15 .45 16 03 16 69 25 .0 29 24 14 19 13 62 13 00 15 .05 15 62 16 24 30 .0 28 63 14 36 13 82 13 23 14 .28 14 82 15 41 40 .0 27 25 14 54 14 06 13 54 12 .71 13 18 13 70 50 .0 26 04 14 62 14 20 13 74 11 42 11 84 12 30 60 .0 24 97 14 66 14 28 13 87 10 30 10 69 11 09 70 .0 23 98 14 70 14 36 13 99 9 28 9 62 9 98 80 .0 23 17 14 76 14 45 14 12 8 42 8 72 9 05 85 0 22 84 14 80 14 51 14 19 8 04 8 32 0 65 90 0 22 82 14 86 14 59 14 27 7 96 8 23 8 55 92 5 22 65 14 91 14. 64 14. 33 7 74 8 01 8. 32 95 0 22 58 14 96 14. 70 14 38 7 62 7. 89 8 20 97 5 22.74 15 55 14 76 14. 45 7 19 7. 98 8 .29 100 0 22.58 15 06 14. 85 14. 51 7 52 7. 73 8 .07

T a b l e 4

Fu n c t i o n s of ac t i v a t i o n for viscous flow in w a t e r - t e r t - b u t a n o l system; A R * - m e an ener gy of a c t i v a t i o n in the range of t e m p e r a t u r e s of 299.15 - 313.15 K, A G * - free ener gy of activat io n, A S * - entropy

of ac t i v a t i o n for v i s c ous flow

A H * AG* , kJmol" 1 T A

_s*.

kJmol-]

x a ,% _{k J m o l -1 299 .15 308 15 313 15 299}

»

308 . 15 313 15 0 15 85 9. 13 8 93 8 83 6 72 6 . 92 7 02 5 24 24 11 68 11 33 11 10 12 56 12 .91 13 14 10 27 99 13. 07 12 63 12 40 14 92 15 .36 15 59 20 29 84 14. 52 14 07 13 84 15 31 15 .77 16 00 30 30 60 15. 25 14 80 14 55 15 35 15 .79 16 05 40 31 01 15. 71 15 29 15 01 15 30 15 .71 16 00 50 31 50 16. 02 15 59 15 32 15 49 15 .91 16 18 60 31 81 16. 24 15 81 15 54 15 5b 16 .00 16 28 70 31 94 16. 41 15 99 15 71 15 53 15 .95 16 23 80 32 65 16. 59 16 14 15 86 16 06 16 .51 16 78 90 33 96 16. 79 16 31 16 03 17 17 17 .65 17 93 95 35 43 16. 93 16 40 16 10 18 50 19 .03 19 32 100 37 32 17. 11 16 54 16 19 20 21 20 .77 21 13 T a b l e 5

Fu n c t i o n s of ac t i v a t i o n for vi sc ous flow of Nal s o l u t i o n s in wate r- - i s o p ro pa no l mixtures; A H * - m e an e n e r g y o f a c t i v a t i o n in th erange of t e m p e r a t u r e s of 2 8 8 . 1 5 - 3 1 3 . 1 5 K, A G * - free ener gy of activat io n, AS* - en tr opy of ac t i v a t i o n for viscous flow, c - Nal c o n c e n t r a t i o n

in mo les per 100 mo les of m i xe d solvent

X -_. % A H * AG*, k J m o l '1 TAS*, kJmol

-1 IPA kJmol 288 15 298. 15 313 15 288 15 298.15 313 15 1 2 3 4 5 7 8 c = 0.5 0 16. 82 9 48 9. 19 8 88 7 33 7.62 7 93 1 . 5 18. 94 10 18 9 .83 9 46 8 75 9.10 9 48 5 .0 23. 85 11 60 11.14 10 59 12 25 12.70 13 26 in .0 27. 54 12 81 12.30 11 60 14 73 15.24 15 95 15 .0 29. 01 13 52 12.96 12 26 15 49 16 .05 16 75

Ta ble 5 (contd) 1 2 3 4 5 6 7 8 20.0 28.63 13.89 13.34 12.71 14.75 15.30 15.92 25.0 28.40 14.17 13.63 13.04 14.23 14.77 15.36 30.0 27.81 14.35 13.84 13.28 13.46 13.97 14.53 40.0 26.62 14.56 14.11 13.61 12.06 12.51 13.01 50.0 25.78 14.68 14.27 13.82 11.10 11.51 11.96 60.0 24.79 14.74 14.37 13.97 10.05 10.42 10.83 70.0 23.86 14.80 14.47 14.11 9.06 9.39 9.75 80.0 23.28 14.89 14.59 14.26 8.39 8.69 9.03 85.0 22.92 14.94 14.67 14.34 7.97 8.25 8.58 90.0 22.86 15.02 14.76 14.42 7.84 8.10 8.44 92.5 22.85 15.08 14.81 14.49 7.77 8.04 8.36 95.0 22.82 15.13 1 4 . B7 14.55 7.68 7.94 8.27 97.5 22.85 15.20 14.93 14.62 7.65 7.92 8.23 100.0 23.18 15.28 15.01 14.67 7.90 8.17 8.50 c 1.0 0 16.36 9.50 9.22 B . 94 6.87 7.15 7.43 1.5 18.56 10.18 9.87 9.41 8.38 B . 70 9.15 5 23.09 11.55 11.13 10.60 11.54 11.96 12.49 10 27.00 12.77 12.26 11.61 14.23 14.73 15.39 15 28.04 13.46 12.93 12.28 14.58 15.11 15.76 20 27.57 13.84 13.33 12.74 13.73 14.24 14.83 25 27.76 14.15 13.63 13.07 13.61 14.13 14.69 30 27.21 14.34 13.85 13.32 12.87 13.36 13.89 40 26.19 14.58 14.14 13.67 11.62 12.05 12.52 50 25.44 14.72 14.32 13.88 10.73 11.12 11.56 60 24.55 14.80 14.44 14.05 9.75 10.11 10.50 70 23.66 14.87 14.56 14.20 8.79 9.10 9.46 80 23.24 14.99 14.69 14.36 8.25 8.55 8.87 85 22.91 15.05 14.78 14.45 7.86 .8.14 8.46 90 22.98 15.60 14.88 14.55 7.39 8.11 8.44 92.5 22.91 16.20 14.93 14.62 7.71 7.98 8.29 95 23.04 16.27 15.00 14.68 7.77 8.04 8.36 97.5 23.23 15.34 15.07 14.74 7.89 8.16 8 . 49 100 23.21 15.41 | 15.16 14.80 7.80 8.05 8.40

Table 5 (contd) 1 2 3 4 5 6 7 8 C = 2.0 0 15.50 9.52 9.29 9.03 5.98 6.21 6.47 1.5 17.72 10.19 9.90 9.58 7.53 7.82 8.14 5.0 22.13 11.51 11.11 10.64 10.62 11.02 11.49 10.0 25.09 12.65 12.22 11.63 12.44 12.87 13.46 15.0 26.35 13.37 12.90 12.31 12.98 13.45 14.04 20 26.41 13.79 13.31 12.78 12.62 13.10 13.63 25 26.62 14.12 13.64 13.13 12.50 12.98 13.49 30 26.36 14.34 13.89 13.39 12.02 12.47 12.97 40 25.63 14.61 14.21 13.75 11.02 11.42 11.88 50 25.03 14.80 14.41 14 .00 10.23 10.62 11.03 60 24.32 14.92 14.56 14.19 9.41 9.76 10.13 70 23.43 15.01 14.70 14.37 8.42 8.73 9.06 80 23.13 15.16 14.87 14.56 7.97 8.26 8.57 85 22.87 15.24 14 .98 14.66 7.63 7 .90 8.21 90 22.84 15.35 15.10 14.78 7.49 7.74 8.06 92.5 23.01 15.42 15.16 14.84 7.59 7.85 8.17 95 23.12 15.49 15.23 14.91 7.63 7.89 8.21 97.5 23.92 15.57 15.31 14.98 7.74 8.01 8.33 100 23.23 15.64 15.40 15.05 7.59 7.82 8.18

F u n c t i o n s of a c t i v a t i o n f o r vi sc ous flow of Nal s o l u t i o n s in wate r- - t e r t - b u t a n o l mixtures; A H * - me an e n er gy of a c t i v a t i o n in the r ange of t e m p e r a t u r e s of 2 9 9 . 1 5 - 3 1 3 . 1 5 K, A G * - free ener gy of ac ti vat io n, A S * - en tr o p y of a c t i v a t i o n for v i s c ous flow, c - Nal c o n c e n t r a t i o n

in moles per 100 m o le s of m i x e d solv ent

X TBA ’ *

A H * , kJmol

AG*, kJmol-1 TAS*, kJmol-1

299.15 308.15 313.15 299.15 308.15 313.15 1 2 3 4 5 6 7 8 c = 0.5 0 15.62 9.17 8.99 8.88 6.45 6.64 6.72 f 5 23.35 11.64 11.32 11.10 11.70 12.03 12.25 10 27.00 13.04 12.64 12.42 13.96 14.36 14.58

Table 6 (contd) 1 2 3 4 5 6 7 8 20 29 .28 14 .53 14 10 13 .88 14 .75 15 .18 15 .40 30 30 .22 15 .28 14 .86 14 .61 14 .93 15 .35 15 .61 40 30 .53 15 .76 15 .36 15 .09 14 .77 15 .16 15 .43 50 31 .09 16 .10 15 .69 15 .42 14 .99 15 .40 15 .66 70 32 13 16 .53 16 .09 15 82 15 .61 16 .04 16 .32 80 32 9 3 16 .71 16 .25 15 99 16 .22 16 .68 16 .94 90 34 31 16 .94 16 .45 16 15 17 .37 17 .86 18 . 16 95 36 75 17 .11 16 .55 16 .24 19 .64 20 .21 20 .51 100 43 21 16 73 16 06 26 48 27 .15 c = 1.0 0 15 23 9 20 9 04 8 93 6 04 6 20 6 .31 5 22 64 11 62 11 32 11 11 11 .02 11 32 11 .53 10 26 22 13 02 12 64 12 43 13 21 13 59 13 .79 20 28 29 14 53 14 13 13 92 13 76 14 17 14 .38 30 29 78 15 30 14 97 14 67 14 48 14 81 15 .12 40 30 58 15 81 15 41 15 14 14 77 15 17 15 .44 50 31 18 16 15 15 74 15 48 15 03 15 44 15 .70 60 31 66 16 40 15 99 15 72 15 25 15 67 15 .94 70 32 21 16 62 16 19 15 92 15 59 16 01 16 28 80 33 07 16 82 16 37 16 10 16 25 16 70 16 97 90 34 95 17 08 16 58 16 28 17 87 18 37 18 67 95 35 92 17 27 16 70 16 39 19 65 20 23 20 54 c = 2.0 0 14 71 9 27 9 10 9 03 5 45 5 61 5 69 5 21 16 11 58 11 33 1 1 14 9 58 9 83 10 03 10 24 65 12 99 12 65 12 47 11 66 12 00 12 18 20 27 53 14 55 14 17 13 98 12 99 13 37 13 56 30 29 03 15 36 14 96 14 75 13 67 14 07 14 28 40 30 05 15 89 15 51 15 25 14 16 14 54 14 80 50 30 55 16 00 15 87 15 64 14 55 14 68 14 91 60 31 83 16 56 16 14 15 88 15 26 15 69 15 94 70 32 63 16 80 16 36 16. 10 15 83 16 28 16 53 80 3 3 62 17 05 16 58 16. 30 16 58 17 04 17 32 90 36 10 17 36 16 84 16 56 18 74 19. 26 19 54 95 38 17 17 60 17 01 16. 68 20 58 21 17 21 49

Fig. 1. Fu nc t i o n s of a c t i vat io n of vi sc ous flow in w a t e r - i s o p r o p a - nol m i x t u r e s at 298.15 K; A G * - free energy, A H * - me an e n er gy (in the range of t e m p e r a t u r e s of 2 8 8 . 1 5 - 3 1 3 . 1 5 K), A S * - en tr o p y of

a c t i v a t i o n of v i s c ous flow

In Fi gu r e s 1 and 2 energy, en tr opy and free ener gy of a c t i v a ­ tion of visc ous flow are p r e s e n t e d as a func tio n of alcohol c o n ­ tents in m i xt ure s of wa ter with IPA and TBA. The ener gy and entropy of a c t i v a t i o n curves of both syst ems d i f f e r in their shapes. Both c u rv es for w a t e r - I P A m i x t u r e s (Figure 1) go thro ugh the maxima

_ J - - - 1- - - 1_ _ _ _ _ _ _ _ _ I_ _ _ _ _ _ _ _ _

20

40

60

80

100

mole % ale.

water - IPA

F i g . 2. F u n c t i o n s of ac t i v a t i o n of vi sc o u s flow in w a t e r - t e r t - b u t a - nol m i x t u r e s at 299.15 K; A G * - free energy, A H * - mean ener gy (in the range of te m p e r a t u r e s of 2 9 9 . 1 5 - 3 1 3 . 1 5 K), A S * - en tr o p y of

w i t h i n the range of 10-15 mol X IPA and very s h a l l o w m i ni ma of about 95 mol X IPA. On the ot her hand the ener gy and entr opy of a c t i v a ­ tion in w a t e r - T B A syst em chan ge the pl ots twice w i th in the range 10-20 mol % TBA and 90 mol % TBA (Figure 2). In c o n t r a d i s t i n c t i o n to the shape of curv es A G * the curv es i l l u s t r a t i n g the d e p e n d e n c e of e n t r o p y and ener gy of a c t i v a t i o n on m i x t u r e c o m p o s i t i o n in water -IPA s y st em are si mi lar in shapes to each ot her wh ich m e a n s that they show a maxi ma in wa ter rich region and a m i ni ma in a lco hol rich region. Maxi ma are found in the range of c o m p o s i t i o n in wh ich many p h y s i c o - c h e m i c a l p r o p e r t i e s of the s y s t e m show ma xi m a l o r d e r i n g of wa ter s t r u c t u r e due to a d d i t i o n of a small amount of alco hol [5-8], In w a t e r - T B A syst em the curv es of ener gy and e n t r o p y of ac t i v a t i o n of vi sc o u s flow are of the shap es very s i m i lar to ea ch other and d i f f e r e n t from the shap es of curv es of free ener gy of a c t i v a t i o n in this system. As it has been m e n t i o n e d above in the range 10-20 mol % TBA there can be o b s e r v e d r e f r a c t i o n s of curv es of e n er gy and entropy of a c t i v a t i o n in the d i s c u s s e d system. The lack of m a x i m a on A H * and T A S* c u rv es (Figure 2) does not perm it to wa tch a c o m p o s i t i o n of the hi gh e s t degr ee of the orde r of the system.

When the c o n t e n t s of w a te r in i n v e s t i g a t e d sy st e m s ex ce eds 15 mol % IPA and about 20 mol % TBA fu rt her a d d i tio n of alcohol s h ou ld ca use b r e a k i n g of the t h r e e - d i m e n s i o n a l lattice of H - bonds in wa ter and thus, ener gy and en tr opy of a c t i v a t i o n of v i s c ous flow s h ou ld diminish. In the w a t e r - I P A s y st em this really h a p p e n s so and the valu es of both f u n c tio ns d e c r e a s e t o g e t h e r with the in crease of al co hol c o n t e n t s up to about 95 mol X, that is up to the c o m p o s i ­ tion be ing in ac c o r d a n c e with the m i n i m u m of ener gy and e t ro py of activat io n. On the other hand in w a t e r - T B A s y st em e n er gy and e n t r opy of a c t i v a t i o n grow to a very little degr ee t o ge the r wi t h the increase of al co hol cont ent up to about 90% TBA. In the case of w a t e r - I P A syst em d e s t r o y i n g wate r s t r u c t u r e by IPA m o l e c u l e s and the pr oc ess of c r e a t i n g va ri ous mi xed a s s o c i a t e s p r o b a b l y do mi nan te , h e nc e a d e c r e a s i n g energy of a c t i v a t i o n can be observed. In w a t e r - T B A syst em the effe ct of d e s t r o y i n g the w a te r s t r u c t u r e will be compensated- by an a s s o c i a t i o n process, the latt er le ad i n g to fo rm ing mixed a s s o c i a t e s of d i f f e r e n t structures. This will ma ke the vi sc ous flow d i f f icu lt be ca u s e of c o n s i d e r a b l e b r a n c h i n g of TBA m o l e cul es . About 90 mol % TBA and 95 mol % IPA the ma xi m a l n u mb er of a s s o c i a t e s of B r o w n and I v e s-ty pe [9] is p r o b a b l y formed. In w a t e r - T B A s y st em the

m i n i m u m of the d i e l e c t r i c p e r m i t t i v i t y is o b s e r v e d at ca. 90 mol %

al co h o l [9, 10] w h ic h may pr ove a m a x i mal s h i e l d i n g of pola r grou ps in w a te r and alcohol m o l e c u l e s by h y d r o p h o b i c chains. A b ov e 90 mol % of TBA the c o n s i d e r a b l e incr eas e of e n er gy and e n t r o p y of a c t i v a t i o n is o b s e r v e d p r o b a b l y c o n n e c t e d with f o r m a t i o n of a s t r u c t u r e charac­ teristic of alcohol [lO] at this c o m p o s i t i o n range.

The ma xi mal va lue of e n er gy and e n t r o p y of a c t i v a t i o n in w a t e r - T B A s y s t e m is o b s e r v e d in pure alco hol and thus the s t r u c t u r e c h a r a c t e r i s t i c of al co hol in the ca se of its b r a n c h i n g m o l e c u l e s (as it is with TBA) make s the V i s c o u s flow c o n s i d e r a b l y d i f f i c u l t and r e q u ire s a gr oat deal of ener gy and e n t r o p y of ac ti vat io n.

In figu re 3 the e n er gy and en tr o p y of a c t i v a t i o n for v i s c ous flow c u r v e s refer to d i f f e r e n t Nal c o n c e n t r a t i o n s (0.5, 1.0, 2.0 mo­ les of salt per 100 m o le s of m i xe d s o l v ent ) in w a t e r - I P A m i x t u r e s at 298. 15 K. The pl ots of ener gy and e n t r o p y of a c t i v a t i o n of Nal s o l u t i o n are a n a l o g o u s to these of m i xe d solvent. They go th ro u g h the m a x i m a about 15 mol % and m i ni ma w i t h i n the range of c o m p o s i t i o n 90 -95 mol % IPA. The a c t i v a t i o n e n e r g i e s of Nal s o l u t i o n for d i f f e r e n t c o n c e n t r a t i o n in w a t e r - I P A m i x t u r e s in the range of c o m p o ­ s i ti on 0-80 mol % IPA are lower than in p u re solvent. It may s u g g est a d e s t r o y i n g effe ct of Nal on the m i x e d s o l v e n t s t r u c t u r e . The h i gh er salt c o n c e n t r a t i o n we have the s t r o n g e r d e s t r o y i n g e f fe ct occurs. Si mi l a r re su l t s were o b t a i n e d for w a te r s o l u t i o n of Nal by G o o d [ll] and M i l l e r and D o r a n [12]. In Mai s o l u t i o n s c o n t a i n i n g more than 80 mol % IPA the a c t i v a t i o n ener gy e x c e e d s the a c t i v a t i o n energy of the solvent, w h ic h may s u g g e s t that in this ra nge of c o m p o s i t i o n s Nal ma kes the o r d e r i n g e f fe ct on the s o l v e n t s t r u c t u r e .

W h il e a n a l y s i n g the c o ur se of c u rv es of a c t i v a t i o n e n t r o p i e s of Nal s o l u t i o n s and the so lv e n t in this s y s t e m in IPA ri ch re gi ons it s h ou ld be o b s e r v e d that ab ove 90 mol % IPA the c u rv es o v e r l a p in all t e m p e r a t u r e s i n v e s t i g a t e d (Figure 3 and 4) on ac co u n t of low valu es AS*. The a c t i v a t i o n e n t r o p i e s for the v i s c o u s fl ow of Nal s o l u t i o n c o n t a i n i n g fr om 0 to 90 mol % IPA are lower than in pure s o l v e n t so in this ra nge of c o m p o s i t i o n Nal d e s t r o y s the s t r u c t u r e of the mixture.

In F i gu re 5 can be found plot s of a c t i v a t i o n e n er gy and e n t r opy of Nal s o l u t i o n (with salt c o n c e n t r a t i o n of 0.5, 1.0, 2.0 mo le of e l e c t r o l y t e per 100 m o l e s of so lv ent ) in the m i x t u r e s of w a te r wi th

Fig. 3. Energy, AH*, and entropy, T A S * , of a c t i v a t i o n of vi sc ous flow of Nal s o l u tio ns in w a t e r - i s o p r o p a n o l m i x t u r e s at 298.15 K; x - solvent, A - 0.5, o - 1.0, • - 2.0 m o le s of Nal per 100 moles

of m i xe d solv ent

TBA vers us TBA co nt ent in the m i xe d so lv e n t at 299.15 K. The shapes of the curves of ac t i v a t i o n ener gy and entr opy of Nal s o l u tio ns are a n a l o g o u s to the curve of the solvent. T o g e t h e r w i th the grow th of TBA cont ent s in the s y s t e m both f u n c t i o n s grow in the w h ol e range

Fig. 4. E n t r opy of a c t i v a t i o n of v i s c o u s flow in w a t e r - i s o p r o p a n o l m i x t u r e s (full lines) and in Nal s o l u t i o n s in this m i x t u r e with c o n ­ c e n t r a t i o n of 2.0 m o le s of salt per 100 m o le s of the m i x e d so lv e n t

(broken lines) at: o,a - 288. 15 and - 313. 15 K

of c o m p o s i t i o n of the solvent. At first, up to 20 mol % TBA the gr ow th is rapid, then the curv es c h an ge their c o u r s e s and up to a b ou t 90 mol % TBA very little grow th is observed. A b ov e 90 mol % TBA agai n a fast g r ow th of a c t i v a t i o n e n er gy and e n t r o p y of both the so lv e n t and Nal s o l u t i o n s can be seen. E n er gy and e n t r o p y of a c t i v a t i o n of Nal s o l u t i o n s are lower than the i d e n tic al f u n c tio ns in pu re so lv ent in the ra nge of 0-65 mol % TBA, which, as it has

mol %TBA

Fig. 5. Energy, A H *, and entropy, TAS*, of ac t i v a t i o n for v i s c o i - flow of Nal so lu tio ns in w a t e r - t e r t - b u t a n o l m i x t u r e s at 259.15 k; x - solvent, a - 0.5, o - 1.0, • - 2.0 mo les of Nal per 100 mole s of

Fig. 6 . En tr o p y of a c t i v a t i o n for v i s c ous flou in w a t e r - t e r t - h u + a no m i x t u r e s (full lines) and of Nal s o l u t i o n s in this m i x t u r e with salt c o n c e n t r a t i o n 2.0 mo les per 100 m o le s of the m i xe d so lv ent

(broken lines) at: o,a - 508. 15 K, . ,9 - 313 15 y

been al re a d y m e n t i o n e d before, su gg e s t the d e s t r o y i n g e f fe ct of the e l e c t r o l y t e on a m i xe d so lv e n t st ru ctu re . In Nal s o l u t i o n s with TBA c o n t e n t s high er than 65 mol % the a c t i v a t i o n e n e r g y and e n t r o p y

e x c e e d s the ac t i v a t i o n ener gy and en tr o p y of the s o l v ent w h ic h makes us think that Nal orde rs the so lv ent structure.

In Figure 6 it is seen that the p o s i t i o n of i n t e r s e c t i o n poin ts of a c t i v a t i o n en tr opy of Nal s o l u t i o n s with the c o n c e n t r a t i o n of 2 mole s of salt per 100 m o le s of so lv e n t and a c t i v a t i o n e n t r o p y of w a t e r - T B A m i x t u r e s does not d e pe nd on the te m p e r a t u r e in the i n v e ­ st i g a t e d range of tempera tu re s. Thus, the in fl uen ce of Nal ch an ges from a de s t r o y i n g one into o r d e r i n g the s t r u c t u r e of the w a t e r - a l c o - hol m i x t u r e about 65 mol X TBA. The sign of the t e m p e r a t u r e c o e f f i ­ cient of the r e la tiv e v i s c osi ty of Nal s o l u t i o n s in w a t e r - T B A syst em (p o s iti ve up to 65 mol % TBA and n e g a t i v e above this c o m p o s i t i o n [3]) su pp o r t this conclusion.

It shou ld be po in t e d out that the i n t e r s e c t i o n point of curv es of a c t i v a t i o n ener gy and e n t r opy of Nal s o l u t i o n s in w a t e r - T B A m i x t u r e s with curv es of the so lv ent is d i s t i n q l t l y cl ear in both a c t i v a t i o n f u n c tio ns and its p o s i t i o n does not d e pe nd on the t e m p e ­ ratu re .

It can be as su med that a c t i v a t i o n ener gy and e n t r opy for vi sc ous flow are f u n c tio ns re f l e c t i n g s t r u c t u r a l ch an g e s in s o l u ­ tions. N e v e r th el es s, it may h a pp en that the c h a n ges of a c t i v a t i o n e n tr o p y of s o l u t i o n s are so scan ty that they cann ot c o n s t i t u t e a base for dr ow i n g any c o n c l u s i o n s c o n c e r n i n g the salt e f f e c t on the s o lv e n t s t r u ctu re as it takes pl ace in the range of al co hol rich c o m p o s i t i o n s in w a t e r - I P A system. The c h a n ges of a c t i v a t i o n energy in this s y st em are more d i s t i n c t than these of a c t i v a t i o n entropy.

The be h a v i o u r s of the i n v e s t i g a t e d sy st e m s are d i f f e r e n t which may s u g g est an unequal i n f l uen ce of a l c o h o l s on w a te r Structure. In the case of s y st em c o n t a i n g TBA it is likely that c l a t h r a t e s exist as it is sh own in the work s by J u i l l a r d and et al.

[ 13] and by I w a s a k i and F u j i y a m a [l4] .

R e fe re n c e s

[l | T a n i e w s k a - O s i r i s k a S., K a c p e r s k a Acta Univ. Lodz., Folia chimica, 2_, 25 (1983). [2] T a n i e w s k a-0 s i ń s k a S., K a c p e r s k a

Acta Univ. Lodz., Folia chimica, 2^ 89 (1983). [3] T a n i e w s k a-0 s i ń s k a S., K a c p e r s k a

[4] The I n t e r n a t i o n a l E n c y c l o p e d i a 0 Ch e m i c a l Physics, Vol. 3, ed. R [5] Water, A C o m p r e h e n s i v e Treatise, (1973). [6] B r u u n S. G . , H v i d t A., £1, 930 (1977). [7] T a n i e w s k a-0 s i ń s k a Obsh. Khim. , 44., 1665 (1974). [B] T a n i e w s k a-0 s i rt s k a 3. Sol. Chem. , J_ , 12 (1978). [9] B r o w n A. C., I v e s D. J. (1962). [10] F r a n k s F., I v e s 0. 3. [11] G o o d W., E l e c t ro ch im . Acta, 11 , 759 (1966); U , 767 (1966); [12] M i l l e r M. L., D o r a n (1956). [13] J u i l l a r d J., M o r e l 3. Chim. P h y s . , _69, 787 (1972). [ 1 4 ] l w a s a k i K . , F u j l y a m (1977). Ph y s i c a l C h e m i s t r y and H. Stokes, New York (1965). Vol. 2 ed. F. Franks, 357

Ber. der B u n s e n - G e s s e l l s c h a f t , S., P i e k a r s k i H., Zh . S., P i e k a r s k i H., G., 3. Chem. Soc., 1 9 6 2 , 160B C., Quart. Rev., 2£, 1 (1966). 9, 203 (1964); 10, 1 (1965); 12, 1031 (1967). M., J. Phys. Chem., 60, 186 J. P . , A v e d i k i a n L., a T., 3. Phys. C h e m . , 81, 1908 Anna K a c p ers ka , S t e f a n i a T a n i e w s k a - O s i ń s k a T E R M O D Y N A M I C Z N E FU NK C3E A K T Y W A C 3 I L E P K I E G O P R Z E P Ł Y W U W U K Ł A D A C H E L E K T R 0 L I T - W 0 D A - R 0 Z P U S Z C Z A L N I K O R G A N I C Z N Y CZĘŚĆ I. R O Z T W O R Y Nal W M I E S Z A N I N A C H WODY Z I Z 0 P R 0 P A N 0 L E M I T E R T - B U T A N O L E M O b l i c z o n o t e r m o d y n a m i c z n e fu nk c j e a k t y wac ji l e p k i e g o p r z e p ł y w u A H *, A S * i A G * dla u k ł a d ó w N a l - w o d a - i z o p r o p a n o l w z a k r e s i e t e m p e ­ r a tu r 2 8 8 . 1 5 - 3 1 3 . 1 5 K i N a l - w o d a - t e r t - b u t a n o l w z a k r e s i e t e m p e r a t u r 2 9 9 . 1 5 - 3 1 3 . 1 5 K. O b l i c z e n i a w y k o n a n o dla r o z t w o r ó w Nal o s t ę ż e ­ n i ac h 0.5, 1.0 i 2.0 m o le soli na 100 moli r o z p u s z c z a l n i k a . U z y s k a ­ ne w y ni ki z i n t e r p r e t o w a n o z punk tu w i d z e n i a w p ł y w u a l k o h o l u na struk­ turę wody oraz Nal na s t r u k t u r ę m i e s z a n e g o r o z p u s z c z a l n i k a .