Relative Viscosity and Free Energy of Activation of Viscous Flow of KNO₃ Solutions in Water-Acetamide Mixtures at Different Temperatures

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 CH IM I C A B, 198B_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ M a r i a n Wold an* R E L A T I V E V I S C O S I T Y AND FREE E N ER GY OF A C T I V A T I O N OF V I S C O U S FLOW OF KNOj S O L U T I O N S IN W A T E R - A C E T A M I D E M I X T U R E S AT D I F F E R E N T T E M P E R A T U R E S The r e l a t i v e v i s c o s i t y of KNO, s o l u t i o n s in w a t e r - a c e t a m i d e m i x t u r e s on the c o n c e n t r a t i o n , t e m p e r a t u r e and the c o m p o s i t i o n of the m i x t u r e is di sc uss ed . The e f f e c t i v e f l o w ing v o lu me of K N O 3 and the free e n e r g y of a c t i v a t i o n of v i s c o u s flow w e re cal­ c u l a t e d and the d e p e n d e n c e of these m a g n i t u d e s on concentration, c o m p o s i t i o n of the w a t e r - a c e t a m i d e m i x t u r e and t e m p e r a t u r e is di sc uss ed . The c o n c l u s i o n about the d i s o r d e r i n g e f fe ct of KNO, on the s t r u c t u r e of w a t e r - a c e t a m i d e m i x t u r e s has been drawn.

The v a r i a t i o n of v i s c o s i t y wi th t e m p e r a t u r e and s o l v ent c o m ­ p o s i t i o n has be en e m p l o y e d to st udy the i o n - s o l v e n t i n t e r a c t i o n by ma n y w o r k e r s [l] both in a q u e ous and n o n a q u e o u s so lu tio ns . The e f ­ fect of e l e c t r o l y t e on the v i s c o s i t y of a s t r u c t u r e d so lv e n t is due to three factors:

a) the s o l v a t i o n of the ions a c c o m p a n i e d by a v i s c o s i t y incr eas e a s s o c i a t e d wi t h the E i n s t e i n volu me e f fe ct (r|E ),

b) long ra nge o r d e r i n g by the ionic fi eld w h ic h al so in cr eas es the v i s c o s i t y of solvent,

c) the so c a l l e d " b r e aki ng " of s o l v e n t s t r u c t u r e by the s o l v a t e d ion w h i c h d e c r e a s e s v i s c o s i t y by d i s r u p t i n g H - b o n d e d gr ou pings.

The d e c r e a s e of v i s c o s i t y due to d i s r u p t i o n of s o l v e n t s t r u c t u r e is e v i d e n t l y m u ch g r e a t e r i m p o r t a n c e for w a te r than for other so lvents. In the p r e v i o u s pa per [2] the r e s u lts of m e a s u r e m e n t s of the v i s c o s i t y of w a t e r - a c e t a m i d e - N a l t e r n a r y s y s t e m and the e f fe ct of Nal on the s t r u c t u r e of w a t e r - a c e t a m i d e m i x t u r e s have be en di sc uss ed . It is k n ow n that KNO-j has a b r e a k i n g effe ct on wa ter st ru cture. Thus it s e em ed i n t e r e s t i n g what is the

influ-

•M-R e s e a r c h and D e v e l o p m e n t C e nt re for Standard •M-R e f e r e n c e Materials WZORMAT - B r an ch in Łódź.

en ce of a d di tio n of a c e t a m i d e on this effect. In the p r e s e n t pa per an a t t e mpt has been made to deal with the i o n - s o l v e n t i n t e r a c ­ tion of KNOj is w a t e r - a c e t a m i d e m i x t u r e s of v a r y i n g c o m p o s i ­ tion to see the effe ct of t e m p e r a t u r e and h y d r o g e n b o n d i n g on the t e m p e r a t u r e c o e f f i c i e n t of r e l a tiv e v i s c o s i t y dr)r /dT and e f f e c t i v e f l o w ing volu me of KNOj. The free ener gy of a c t i v a t i o n of the vi s c ous flow of these s o l u t i o n s have also be en c a l c u l a t e d for i n t e r p r e t i n g the i n f l uen ce of KNO-j upon the v i s c o s i t y of the w a t e r - a c e t a m i d e m i x t u r e s as a rate process.

J j x £e ri me n ta lt

The m e t h o d of p u r i f i c a t i o n of a c e t a m i d e and KNO^ and the p r o ­ c e du re of m e a s u r e m e n t s of v i s c o s i t y were d e s c r i b e d e a r l i e r [3], The re su l t s of v i s c o s i t y m e a s u r e m e n t s of KNO-j s o l u t i o n s ma de at a s e ri es of c o n c e n t r a t i o n c o v e r i n g the range 0 . 0 2 - 0 . 5 m o le d m -î in the m i x t ure c o n t a i n i n g 5, 15, 30, 50 and 70 wt% of A c N H 2 in wa ter at 25, 40, 60, 75 and 85°C were p r e s e n t e d p r e v i o u s l y [3].

_ R e s u H s _ a n d _ D ^ £ u s s i o n

The re la tiv e v i s c osi ty of KNO^ s o l u t i o n s in w a t e r - a c e t a m i d e m i x t u r e s is p r e s e n t e d in Fi gu r e s 1-5. As it is seen from F i g u r e s 1-5 the r e la tiv e v i s c o s i t y of KNO^ s o l u t i o n s in w a t e r - a c e t a m i d e m i x t u r e s in cr eas es with the rise of c o n c e n t r a t i o n of e l e c t r o l y t e exce pt of m i x t u r e s c o n t a i n i n g s m a l ler than 50 w t !6 of A c N H 2 at 25°C. The i n cr eas e of the c o n t e n t s of a c e t a m i d e in the m i x e d solvent c a us es the rise of r e l a tiv e v i s c o s i t y s i m i l a r as the i n c r e a s e of te mp era tu re . It can be s u p p o s e d that the i n cr eas e of re la tiv e v i s c o s i t y of the d i s c u s s e d s y s t e m s is c a us ed by g r o w i n g v o lu me of s o l v a t i o n layers arou nd ions. From p a pe rs [4-6] it is f o l l ows that the t e m p e r a t u r e c o e f f i c i e n t of r e l a t i v e v i s c o s i t y dT) r /dT b e tt er i l l u s t r a t e s the s t r u ctu ra l c h a n g e s taki ng p l ac e in the s o l u t i o n than r e l a t i v e viscosity. In case of the e l e c t r o l y t e s o r d e r i n g s o l v ent s t r u c t u r e the dr) r /dT c o e f f i c i e n t is n e g a t i v e and it is po s i t i v e for s t r u c t u r e b r e a k i n g el ec t r o l y t e s . The values of drj f /dT c o e f f i c i e n t c a l c u l a t e d a n a l y t i c a l l y for w a t e r - a c e t a m i d e - K N O ^ te r n ary s y st em are g i ve n in Ta ble 1.

— I--- 1 <--- 1--- 1- - - ► 0.1 0.2 0.3 0.4 0.5 [ mol • kg'1 ] Fig. 1. R e l a t i v e v i s c o s i t y of K f ^ s o l u t i o n s in w a t e r - a c e t a m i d e m i x t u r e s vs c o n c e n t r a t i o n of K N 03(m) and c o m p o s i t i o n of m i x t u r e at 25°C: I - H 2O, 2-5 wt% A c N H 2 , 3-15 wt X A c N H 2 , 4-30 wtX A c N H 2 , 5-50 w t X A c N H 2 Fig. 2. R e l a t i v e v i s c o s i t y of K N O 3 s o l u t i o n s in w a t e r - a c e t a m i d e m i x t u r e s vs c o n c e n t r a t i o n of K N 03(m) and c o m p o s i t i o n of m i x t u r e at 40°C: 1-H20, 2-5 wtX A c N H 2 , 3-15 wtX A c N H 2 , 4-30 w t X A c N H 2 , 5-50 w t X A c N H 2 ■*> R e l a t i v e V i s c o s i t y an d Fr ee E n e r g y

Fig. 3. R e l a t i v e v i s c o s i t y of K N O 3 s o l u t i o n s in w a t e r - a c e t a m i d e m i x t u r e s vs c o n c e n t r a t i o n of K N 03(m) and c o m p o s i t i o n of m i x t u r e at 60°C : 1 - H 20, 2-5 w t * A c N H 2 , 3-15 wtX A c N H 2 , 4-30 wt% A c N H 2 , 5-5Û wt!S A c N H 2 , 6- 70 wtS AciÎH2 0.4 0.5 [ m o l - k g 1] Fig. 4. R e l a t i v e v i s c o s i t y of K N O 3 s o l u t i o n s in w a t e r - a c e t a m i d e m i x t u r e s vs c o n c e n t r a t i o n of K N 03(m) and c o m p o s i t i o n of m i x t u r e at 75°C: 1 - H 20, 2-5 wt% A c N H 2 , 3-15 w t % A c N H 2 , 4-30 w t X AcNH2 , 5-50 wtX A c N H 2 , 6-70 wt* A c N H 2 M a r i a n W o l d a n

Fig. 5. R e l a t i v e vi sc o s i t y of K N G 3 s o l u t i o n s in w a t e r - a c e t a m i d e mi x t u r e s vs c o n c e n t r a t i o n of KNC^Cm) and c o m p o s i t i o n of m i x t u r e at 85°C : 1-H_> 0, 2-5 wtX Ac N H 2 , 3 - 1 5 wtX A c N H 2 , 4-30 wtX A c N H 2> 5-50 wtX

A c N H 2 , 6-70 wtX A c N H 2 , 7-85 wtX AcNHj, 8-95 wtX A c N H 2

As it is seen from Table 1 the valu es of dt| r /dT c o e f f i c i e n t of i n v e s t i g a t e d s y s t e m are p o s i t i v e in the w h ol e range of i n v e s t i g a ­ ted c o n c e n t r a t i o n s and c o m p o s i t i o n s of m i x e d solvent. It is easy to n o t i c e that c o e f f i c i e n t d rj r /dT i n c r eas es with the rise of c o n ­ c e n t r a t i o n of KNOj in the s o l u t i o n and it d e c r e a s e s wi th the in ­ c r ea se in te m p e r a t u r e and c o n t ent s of a c e t a m i d e in the mixture. From this one can c o n c l u d e that KNOj has d i s o r d e r i n g e f fe ct on the s t r u c t u r e of w a t e r - a c e t a m i d e mi xtures. This e f fe ct i n c r eas es

T a b l e 1

The valu es of di-| r /dT of KNO^ s o l u t i o n in w a t e r - a c e t a m i d e m i x t u r e s [ l .l O- ^ deg

m K N 0j Water 95 wtX H 2 ()-5 w t X AcNH 2 85 wtX H2D-15 w t X A c N H 2 [mol .kg-1] 25° 40° 60° 75° 85° 25° 40° 60° 75° 85° 25° 40 0 60° 75° 85° 0.05 2.2 1.6 1.1 0.9 0.8 2.2 1.6 1.2 1.0 0.9 2.2 1 .6 1.2 1.0 0.9 0.10 4.3 3.3 2.4 2.0 1.8 4.1 3.2 2.3 1.9 1.7 4.1 3. 2 2.3 1.9 1.7 0.20 8.6 6.7 4.8 4.0 3.4 8.3 6.6 4.8 3.7 3.1 8.0 7. 5 4.8 3.8 3.2 0.30 12.8 10.0 7.2 5.7 5.2 12.2 9.7 7.0 5.4 4.8 12.2 9. 6 7.0 5.6 4.8 0.40 16.0 13.2 10.2 8.4 7.4 16.3 12.9 9.6 7.5 6.6 16.3 12.9 9.3 7.6 7.0 0.50 20.4 16.4 12.2 9.8 8.6 20.4 15.9 11.5 9.3 8.6 20.4 15. 9 11.5 9.4 8.6 m KN0, 70 wtX H 20-30 w t X A c N H 2 50 w t X H 2 0-50 wtX A c N H 2 70 wtX AcN H 2 -30 wtX H 2 0 [ m o l . k g -1] 25° 40° 60° 75° 85° 25° 40° 60° 75° 85° 60 D 75° 85° 0 . 05 2.1 1.5 1.0 0.9 -0.8 1.8 1.4 1.0 0.8 0.7 0.8 0.8 0 .7 0.10 3.8 3.0 2.2 1.7 1.6 3.6 2.8 2.1 1.8 1.6 1.8 1.7 1 6 0.20 7.9 6.1 4.2 3.3 3.0 6.9 5.5 4.1 3.5 3.3 3.S 3.2 2 9 0.30 11.8 9.2 6.4 5.1 4.7 10.4 8.4 6.1 5.2 4.9 5. 3 4.8 4 6 0.40 15.8 12.1 8.4 6.7 6.1 13.6 11.0 8.3 7.0 6.6 6.8 6.5 6 2 0.50 19.6 15.0 10.6 8.6 7.9 17.1 14 .0 10.6 8.5 7.6 9. 1 7.5 6 5

w i th the rise of c o n c e n t r a t i o n of KNOj but it d e c r e a s e s w i th the rise in t e m p e r a t u r e and c o n t e n t s of a c e t a m i d e in the mixture. From this it f o l l ows that the i n f l u e n c e of a d d i t i o n of a c e t a m i d e on w a t e r - KNOj i n t e r a c t i o n s is s i m i l a r to t e m p e r a t u r e effect. It is k n ow n that the i n c r e a s e of t e m p e r a t u r e d i s o r d e r s the s t r u c ­ ture of solution, t h e r e f o r e one can c o n c l u d e that a d d i t i o n of a c e t a m i d e to wate r d e c r e a s e s the d i s o r d e r i n g e f fe ct of KNO-j on w a t e r st ru cture. One can s u p p o s e that the m o l e c u l e s of a c e t a m i d e form with w a te r the m i x e d a s s o c i a t e s in w h ic h the H - b o n d s are s l i g h t l y w e a k e r than h y d r o g e n bo nds in p u re w a t e r [7, 8].

In o r de r to veri fy the h y p o t h e s i s that the v o lu me of s o l v a t i o n laye rs i n cr eas e with the rise of t e m p e r a t u r e and c o n t e n t s of a c e ­ tami de in the m i x e d so lv e n t the valu es of e f f e c t i v e f l o w ing v o lu me of KNOj in w a t e r - a c e t a m i d e m i x t u r e s we r e c a l c u l a t e d on the basi s of E i n s t e i n ’s e q u a t i o n [9] :

w h e r e $ is the f r a c t i o n of volu me o c c u p i e s by one m o le of solu te p a r t i c l e s in so lu tion. B r e s l a u and M i l l e r [10] have a s s u m e d that $ = V g .c w h e r e V Q is the e f f e c t i v e r i gi d m o la r v o lu me of f l o w i n g and c is mo la rity. This V 0 has been s t r i c t l y d e f i n e d as the v o l u m e w h ic h a mo le of solu te p a r t i c l e s o c c u p i e s when considered, fr o m p u r e l y h y d r o d y n a m i c reasons, as ri gid m i c r o s c o p i c spheres. In case of e l e c t r o l y t e s V g may be r e g a r d e d a 3 the v o lu me of ions form ed from one mo l e of e l e c t r o l y t e t o g e the r w i th their s o l v a t i o n laye rs

[ l l ] . F i n a l l y the valu es of e f f e c t i v e m o la r v o l u m e of f l o w i n g for KNQj in w a t e r - a c e t a m i d e m i x t u r e s w e re c a l c u l a t e d from

As it is seen from F i gu re 6 the e f f e c t i v e m o l a r v o l u m e of KNOj in w a t e r - a c e t a m i d e m i x t u r e s d e c r e a s e s a litt le w i t h the ri se of c o n c e n t r a t i o n of e l e c t ro ly te . By e x t r a p o l a t i o n of V g to c = 0 were e s t i m a t e d the l i m i t i n g e f f e c t i v e m o l a r f l o w i n g vo lumes, V°. The valu es of V^ o b t a i n e d are c o l l e c t e d in Ta ble 2 and p r e s e n t e d in F i g u r e 7 and 8 as a f u n c t i o n of the c o m p o s i t i o n of m i x e d so lv e n t and te mp era tu re .

The i n c r e a s e of c o n t e n t s of a c e t a m i d e in m i x t u r e c a u s e s the gra­

(1)

dual rise of \l° (Figure 7). Simi lar in cr e a s e s wi th the rise of te m p e r a t u r e (Figure 8). It is prov es that the volume of h y d r o d y n a m i c unit in cr eas es wi th the i n c r eas e of c o n t e n t s of a c e t a m i d e and

Fig. 6 . The de p e n d e n c e of the e f f e c t i v e m o la r volume of fl ow i n g for K N O 3 in w a t e r - a c e t a m i d e m i x t u r e s vs c o n c e n t r a t i o n of K N O 3 (m) and c o m p o s i t i o n of m i x t ure at d i f f e r e n t tempera tu re s: 1-H? 0, 2-5 wt% Ac N H 2 , 3-15 wt% A c N H 2 , 4-30 wt% A c N H 2 , 5-50 wt% A c N H 2 , 6-70 wtS

T a b l e 2 The v a lu es of v'2 , V° and V golv for K N 0 3

in w a t e r - a c e t a m i d e m i x t u r e s [cm5 m o l ’ 1]

T

Wate r 5 wt% AcNH^ 15 wtX A c N H 2

[ ° c j V°

2 *e° V sol V V° * 2 V solv V° vsol V

25 38.0 -24 0 -62 0 39.0 -22 4 -61 4 41.0 -19 2 -60.2 40 39.3 -1 6 -40 9 40.4 -0 4 -40 8 42.4 2 4 -40.0 60 40.4 20 8 -19 6 42.0 22 0 -20 0 44 .6 24 8 -19.8 75 41.0 33 6 -7 4 42.7 34 4 -8 3 45.6 37 6 - 8.0 85 41.1 40 8 -0 3 42.7 41 6 -1 1 45.0 44 8 -0.2 j 30 wt% A c N H 2 50 wt% A c N H 2 70 wt% A c N H 2 [°C] VI _{V sol V} V° v° (n o rH > l > V° ^sol V 25 44.0 -12 0 -56 0 48.0 -0 8 -48 8 - _ _ 40 45.6 8 8 -36 8 49.0 17 6 -31 4 - - -60 47.0 29 2 -17 8 49.9 38 0 -11 9 51.2 51 6 0.4 75 40.0 41 6 -6 4 49.8 49 2 -0 6 50.6 61 6 1 1 . 0 85 47.7 48 0 0 3 49.4 56 0 6 6 50.0 68 0 18.0

t e m p era tu re . The n e g a t i v e values of V° for KNOj at 25°C one can e x p l a i n by large b r e a k i n g effe ct of KNO^ on the s t r u c t u r e of w a t e r - a c e t a m i d e mi xt ure s. At h i gh er t e m p e r a t u r e the m i x e d w a te r- a c e t a m i d e a s s o c i a t e s with w e ak er than in w a t e r H - b o n d s are mo re s u s c e p t i b l e 5 to d i s r u p t i o n than w a te r as so cia te s. More free m o l e ­ cu les w h ic h can take part in ionic s o l v a t i o n appe ar then in the s o lu tio n. S i m i l a r e f fe ct on s o l v a t i o n of KNO^ has acetamide. T h e r e f o r e one can say that a c e t a m i d e d i s o r d e r s of w a t e r st ru ctu re .

M o re i n f o r m a t i o n s c o n c e r n i n g of i n t e r a c t i o n s KN Oj- m i x e d solvent one can o b ta in fr om the d e p e n d e n c e of v o lu me of s o l v a t i o n layers a r ou nd ions on the c o m p o s i t i o n of m i x e d so lv e n t and te mp era tu re . The v o lu me of s o l v a t i o n layers, V s o i v one can c a l c u l a t e from e q u a ­ tion .

VS * *5 • » S O lv ° >

Fig. 7. The d e p e n d e n c e of the l i m i tin g e f ­ f e c t i v e m o l a r v o lu me of flowing, V|, for K N O 3 in w a t e r - a c e t a m i d e m i x t u r e s vs c o m p o s i t i o n of

m i x t u r e at d i f f e r e n t t e m p e r a t u r e s

Fig. 8 . The d e p e n d e n c e of the l i m i t i n g e f ­ fe c t i v e m o la r v o l u m e of fl owing, V§, for K N O 3 in w a t e r - a c e t a m i d e m i x t u r e s vs t e m p e ra tu re : 1 - H 20, 2-5 wt% A c N H 2 , 3-15 wtX A c N H 2 , 4-30 wtX A c N H 2 , 5-50 wtX A c N H 2 , 6- 70 wt X A c N H 2 M a r i a n W o l d a n

wh er e V° is the pa rt i a l mo lal v o lu me of el ec t r o l y t e . The values of V g Q i v o b t a i n e d for KNO^ in w a t e r - a c e t a m i d e m i x t u r e s are gi ven in Ta ble 2.

As it is se en from Table 2 the v o lu me of s o l v a t i o n layers for KNOj is n e g a t i v e e x ce pt the m i xe d s o l v e n t s c o n t a i n i n g 70 wt% of A c N H 2 and the m i x t u r e s c o n t a i n i n g 30 and more wt% of Ac NF^ at 85°C. The v a lu es of V „ „ lw _{sol v} i n c r eas e w i th the rise of c o n t e n t s of A c N H 0 ₂ in m i x e d s o l v ent and t e m p e r a t u r e (see F i gu re 9). P r o b a b l y it is c a us es by d i s o r d e r i n g e f fe ct of t e m p e r a t u r e and a d d i t i o n of aceta-m i de on w a te r st ru cture. F r oaceta-m F i gu re 9 one can e s t i aceta-m a t e the v alu e of t e m p e r a t u r e s (T ) for w h ic h V g o i v is equal to zero i.e. the KNOj is no ns o l v a t e d . The t e m p e r a t u r e T Q de pe n d s on c o m p o s i t i o n of w a te r-- a c e t a m i d e m i x t u r e and it d e c r e a s e s wi th the rise of c o n t e n t s of a c e t a m i d e in the m i x t u r e (Fig ure 10). T h e r e f o r e one can c o n c l u d e that in ca ses w h en Vs q1v is n e g a t i v e the v i s c o s i t y of m i x e d s o l v ent a r ou nd ions K +N0j s u m m a r y is s m a l l e r than v i s c o s i t y in bu lk of s o lvent. It p r o v e s that in this ca se KNO^ d i s o r d e r s the s t r u c t u r e of w a t e r - a c e t a m i d e mi xt ure s. In case when ^s o i s/ > 0 , K N 0 j is p o s i t i v e s o l v a t e d and it c a us es the i n cr eas e in v i s c o s i t y of m i x e d solvent. The c o n c l u s i o n s o b t a i n e d from the a n a l y s i s of the f u n c t i o n V , =

sol v = f ( x A c ^H . T) are c o n f i r m e d by the c o ur se of the d e p e n d e n c e of v o lu me e x p a n s i o n c o e f f i c i e n t oc of w a t e r - a c e t a m i d e - K N O ^ te rn ary s y s t e m as a f u n c t i o n of the c o m p o s i t i o n of m i x t u r e and t e m p e r a t u r e [.12] . A c c o r d i n g to E y r i n g ’s theo ry c o n c e r n i n g l a m i n a r flow of liquid [13] the d y n a m i c v i s c o s i t y of s o l u t i o n can be d e s c r i b e d by e q u a t i o n

I ■

f

w h e r e h is P l a n c k ’s co ns tan t, N is A v o g a d r o ’s number, V is m o la r v o lu me of solvent, R is the gas co ns tant, T is the t e m p e r a t u r e in K e l v i n and A G * , A S * and A H * are free energy, e n t r o p y and enthalpy of a c t i v a t i o n of v i s c ous flow r e s p e ct iv el y. The v a lu es of p a r t i ­ c u la r 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 were c a l c u l a t e d from f o l l o w i n g formulas: A G * = RT l n ( S ) A H * = R d ln rç /d(y) (5) (6)

Fig. 9. The d e p e n d e n c e of V s 0iv f ° r KNO^ in w a t e r - a c e t a m i d e m i x t u r e s vs te mp era tu re : 1-15 wt% A c N H 2 , 2-30 wt% A c N H 2 , 3-50 w t * A c N H 2 , 4-7Ó wt% Ac n h2 V/» ON

Fig. 9. The d e p e n d e n c e of VgQ-^v = 0 f o r KNOj in w a t e r - a c e t a m i d e m i x t u r e s vs c o m p o s i t i o n of mi x t u r e M a r i a n W o l d a n

The valu es of free e n er gy of a c t i v a t i o n of v i s c o u s flow for w a t e r - a c e t a m i d e - K N O j t e r n ary s y st em [k.l.mol-1]

(X - p e r c e n t a g e by w e i g h t of A c N H 2 ) c K N 0 3 [ m o l . d m ’ 3] OX 5X 15X 30X 50X a) 25° C 0.02 7.00 7.31 7.95 8.99 10.61 0.05 7.00 7.31 7.95 8.98 10.61 0.07 7.00 7.31 7.95 8.98 10.61 0.10 6.99 7.30 7.94 B . 98 10.61 0.15 6.98 7.30 7.94 8.98 10.61 0.20 6.98 7.29 7.93 8.97 10.61 0.30 6.96 7.28 7.92 8.97 10.61 0.40 6.95 7.26 7.91 8.96 10.61 0.50 6.93 7.25 7.90 8.95 10.61 b) 40°( 0.02 6.56 6.86 7.50 8.51 10.05 0.05 II II II 8. 52 II 0.07 II II II II II 0.10 II 6.87 II II 10.06 0.15 II II II II II 0.20 II II II II 10.07 0.30 II II II 8.53 10.08 0.40 II II 7.51 B . 54 10.09 0.50 II 11 11 II 10.10

Table 3 (contd) C K N 0 3 [ m o l .d m ’ 5] 0% 5% 15* 30* 50* 70* c) 60°C 0.02 6.08 6.38 7.00 8 .00 9.52 12.24 0.05 li II II 8.01 9.53 12.25 0.07 6.09 II 7.01 II II 12.26 0.10 II 6.39 II 8.02 9.54 12.27 0.15 6.10 6.40 7.02 8.03 9.55 12.29 0.20 6.11 " 7.03 8.04 9.56 12.31 0.30 6.12 6.42 7.05 8.06 9.60 12.35 0.40 6.14 6.44 7 .06 8.08 9.62 12.39 0.50 6.15 6.45 7.08 8.10 9.64 12.42 d) 75°C 0.02 5.77 6.06 6.63 7.62 9.18 11.00 0.05 5.78 II 6.64 7.63 9.19 11.01 0.07 5.79 6.07 6.65 II 9.20 11.03 0.10 5.80 6.08 6.66 7.64 9.21 11.04 0.15 5.81 6.09 6.67 7 .66 9.23 11.06 0.20 5.82 6.10 6.68 7.67 9.25 11.08 0.30 5.84 6.13 6.71 7.70 9.28 11.13 0.40 5.87 6.15 6.74 7.73 9.32 11.17 0.50 5.89 6.17 6.76 7.76 9.35 11.21 e) 8 5°C 0.02 5.59 5.86 6.41 7.42 8.97 10.73 0.05 5.60 5.87 6 . 42 7.43 8 .99 10.74 0.07 II li 6.43 7.44 9.00 10.75 0.10 5.61 5 .88 6.44 7.45 9.01 10.77 0.15 5.63 5.90 6.46 7.47 9.03 10.79 0.20 5.65 5.91 6.47 7.49 9.05 10.82 0.30 5.67 5 .94 6.51 7.52 9.09 10.87 0.40 5.70 5.97 5.54 7.56 9.13 10.92 0.50 5.73 6.00 6.57 7.59 9.17 10.96

A S * = (AH* - A G * ) / T (7)

In Table 3 the valu es of A G * for w a t e r - a c e t a m i d e - K N O j ternary s y s t e m are gi ven only b e c a u s e the c h a r a c t e r of c h a n g e s of A H * and AS* on c o n c e n t r a t i o n of KNOj, c o n t e n t s of A c N H 2 and t e m p e r a t u r e is i d en tic al as in case of AG*.

Fr om l i t e r a t u r e [14-15] it fo ll ows that in c a se when the e l e c t r o ­ lyte o r de rs the s t r u c t u r e of w a te r the free e n e r g y of a c t i v a t i o n of vi sc o u s flow i n c r e a s e s with the rise of c o n c e n t r a t i o n of solu­ tion and inversely. As it can be seen from Table 3 in case of KNOj s o l u t i o n s in w a t e r - a c e t a m i d e m i x t u r e s the valu es of A G * at 25 and 40 C are p r a c t i c a l l y co nstant. On the ot her hand the increase of a c e t a m i d e c o n t e n t s in m i x t u r e c a us es the rise in va lue AG*. One can be s u p p o s e that KNOj at 25 and 40°C does not c h an ge the i n t e r a c t i o n s am ong w a te r and a c e t a m i d e m o l e cul es . The a d d i t i o n of a c e t a m i d e c a us es the i n cr eas e in AG*. P r o b a b l y it is c o n n e c t e d with the f o r m a t i o n of g r e a ter and g r e a t e r a m o u n t s of m i x e d a s s o ­ ciat es h a v i n g t h r e e d i m e n s i o n a l st ru ctu re , w h ic h m a k e s the vi sc ous flow of s o l u t i o n m o re di ff icult. At 60°C and h i g h e r the v a lu es A G * i n c r eas e with the rise of c o n c e n t r a t i o n of KNOj in solution.

Fr.om this one can c o n c l u d e that in this case KNO^ is p o s i t i v e s o l v a t e d and it m a ke s the vi sc ous flow of s o l u t i o n more di ff icult. It is ob vi o u s that the i n c r eas e of t e m p e r a t u r e of s o l u t i o n c a us es l o o s e n i n g of s t r u c t u r e be ca u s e of d i s o r d e r i n g it by s t r o n g e r thermal m o t i o n s of m o l e cul es . This effe ct m a ke s e a s i e r the v i s c ous flow of s o l u t i o n and the values of A G * decrease.

The c o n c l u s i o n s o b t a i n e d in this p a pe r are in a g r e e m e n t with the c o n c l u s i o n f o l l o w i n g from the a n al ysi s of B c o e f f i c i e n t of the Jones- - D o l e ’s e q u a t i o n on co nc e n t r a t i o n , c o m p o s i t i o n of m i xe d s o l v e n t and t e m p e r a t u r e [3] for w a t e r - a c e t a m i d e - K N O ^ system.

R e f e r e n c e s

[1] S t o k e s R. H., M i 1 1 s R., 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 of Ph ys ica l C h e m i s t r y and C h e m i c a l Physics, Vol. 3, P e r g a m o n Press, New York (1965).

[2] T a n i e w s k a-0 s i r t s k a S., W 0 1 d a n M . , Acta Univ. Lodz., Folia Chim., 1 , 121 (1982).

[3] W o l d a n M., J. Chem. Eng. Data, 30(4), 479 (1985).

[

]

[5] T a n i e w s k a-0 s i r t s k a S., W o l d a n M., Zesz.Nauk. Uniw. Ł odz., Ser. II, z. J24, 33 (1978).

[6] S t 0 k e s R. H., M i 1 1 s R., V i s c o s i t y of E l e c t r o l y t e s and Re la t e d Propert ie s, New York (1965).

[7] G o n c h a r o v V., Y a s t r e m s k i P . S . , Izv. Vyssh. Ucheb. Zaved. Khim. Khim. Tekhnol., 19, 4, 602 (1976).

[a] G o n c h a r o v V . , L j a s h c h e n k o A . K . , Y a s t ­ r e m s k i P. S., Zhur. S t r u k t . Khim., 1 J , 4, 662 (1976). [9] E i n s t e i n A., Annal. Phys., 34, 591 (1911).

[10] B r e s l a u B. R., M i 1 1 e r J. F., J. Phys. Chem., 7<4, 1056 (1970).

[11] R o b i n s o n R. A . , S t o k e s R. H., E l e c t r o l y t e S o l u ­ tions, B u t t e r w o r t h s Sei. Publ., L o nd on (1959).

[12] W o l d a n M., Acta Univ. Lodz., Folia chim. , 5_, 105 (1985). [13] G 1 a s s t o n e S., L a i d 1 e r K., E y r i n g G., The

Theo ry of Rate Pr oc esses, New York (1941).

[14] G o o d W., El ec tro ch im . , Acta, 9_, 203 (1964); 10, 1 (1965); U , 759 (1966); 12, 1031 (1967). [15] N i g h t i n g a l e E. R., B e n c k R. F., J. Phys.Chem., 63, 1777 (1959). M a r i a n W o ld an LE PK 0Ś6 W Z GL ĘDN A I EN ER G I A S W O B O D N A A K T Y WAC JI L E P K I E G O P R Z E P Ł Y W U R 0 Z W T W 0 R Ó W K N O 3 W M I E S Z A N I N A C H W O D A - A C E T A M I D W KI LKU T E M P E R A T U R A C H

P r z e d y s k u t o w a n o z a l e ż n o ś ć lepk ośc i w z g l ę d n e j r o z w t o r ó w KNO3 w m i e s z a n i n a c h w o d a - a c e t a m i d w za l e ż n o ś c i od s t ę ż e n i a r o z t w o r u , tem­ pe ra tur y i skła du mi es zan in y. O b l i c z o n o i p r z e d y s k u t o w a n o z a l e ż n o ś ć ef e k t y w n e j molo wej ob ję toś ci l e p k i e g o p r z e p ł y w u K N O 3 i en er gii s w o ­ bodnej a k t y wac ji le pk ieg o p r z e p ł y w u w za le żno śc i od st ęż enia, s k ł a ­ du m i e s z a n i n y w o d a - a c e t a m i d i te mp era tu ry . W y s n u t o w n i o s e k o n i s z ­ c z ąc ym w p ł y wie K N O 3 na s t r u k t u r ę m i e s z a n i n wo da - a c e t a m i d .