化 学物理 学报 第 巧 拴 第 4期 2 02年 8月 CHI NESE JOURNAL OF CHEMI CAL PHYSI CS N 2 [ . 1 [ } 1 4 2 V o l . A 1 u 5 g [0 3- 7713/20 2/04- 303- 4 I nf luence of Nonvol at i l e Sol ut e o n Bo i l i ng Po i nt o f Az e o t r o pe* S u n Re n y i . ’ De p ar t me n t o f Ch e mi s t y, r He n a n Un i v e r s i y, t Ka i f e n g 47 5 0 01 ) Sun Qi a n (De pa r t me t n o f Ch e mi s t y, r Ea s t Ch i n a No r ma l Un i v e r s i t y, S h a n g h ai 2 0 0 0 6 2) Abs t r a t T c h e i n f l u e n c e o f 1 0 n o n v o l a t i l e s o l u t e s o n b o i i l n g p o i n t o f me t h a n o l - t e t r a h y d r o f u mn a z e o t op r e wa s d e t e r mi n e d b y me a n s o f i s o b a r i c v a po r - l i q u i d e qu i ib l r i u m e x p e r i me n t s . Ba s e d o n c l a s s i c a l t h e r mo d y n a mi c s a c o n c l u s i o n o f u n i v e r s a l s i g n i fc a oc e wa s d e r i v e d, i . e .,a it l t l e n o n v o l a t i l e s o l u t e a l wa y s c a u s e s t h e e l e v a t i o n o f a z e o t r o p e' s b o i l i n g p o i n t i r r e s p e c - t i v e o f t h e v a r i a t i o n o f i t s v a p o r c o mp o s i t i o n . I t i s i n a g r e e me n t wi t h t h e e x p e r i me n t a l es r u l t s a n d t h e el r e v a n t r e po r t s i n t h e l i t e r a t u e r wi t h o u t e x c e p t i o n. Ke y wo r ds Me t h a n o l , Te t r a h y d r a f u r a n, No n v o l a t i l e s o l u t e, Az e o t op r s, B o i in l g p o i n t CLC -. . . her一〔3 645.1 6 Doer - l code, A 1 I nt roduct i on 2.1 M at eri al s A lo f t h e r e a g e nt s us e d i n t hi s pa pe r we r e a n a l y t i - a l r e a g e n t g r a d e . Th e s o l i d n o n v o l a t i l e s o l u t e s we r e Th e i n lu f e n c e o f n o n v o l a t i l e s o l u t e o n b o i l i n g p o i n t c o f l i q u i d mi x t u es r i s o f i mp o r t a n t s i g n i f i c a n c e i n g u i d i n g d r i e d a t 1 2 09 0 f o r 2 4 h p r i o r t o e x p e r i me n t s . Me t h a n o l s c i e n t i ic f r e s e a r c h e s a n d pr odu c t i o n p r a c ic t e s . As e v e - a n d t e t r a h y d of r u r a n we r e f u r t h e r p u r i f i e d a c c o r d i n g t o h e s t a n d a r d me t h o d, t he i r r e f r a c t i o n i n d e x e s(r n t z n c) rb y o d y k n o ws, n o n v o l a t i l e s o l u t e a l wa y s c a u s e s t h e t e 1 . 3 28 6 a n d 1. 4 07 0, r e s p e c t i v e l y. b o i l i n g p o i n t e l e v a t i o n i n p u r e s o l v e n t , h o we v e r , a n o m- wer . 2 App a r a t u s a nd p r o c e du r e a l o u s v a r i a t i o n o f b o i l i ng p o i n t d e p r e s s i o n i s p o s s i bl e a s 2 w e l l s o me t i me s i n mi x e d s o l v e n t " " 1 . N e v e t r h e l e s s , a Al v a p o r - l i q u i d e q u i l i b r i u m me a s u r e me n t s we r e l i t e r a t ur e s u r v e y s h o ws t ha t n o nv o l a t i l e s o l u t e a l wa y s ma d e b y us i n g a mo di ie f d r e c i r c ul a t i o n s t i l l o f Ot h me r c a u s e s t h e b o i l i n g p o i n t e l e v a i t o n o f a z e o t op r e, s u c h a s t y p e f o r s a l t e fe c t s t u d i e s . De t a i l s o f t h e s t i l l a n d e x t h e b o i l i n g p o i nt e l e v a t i o n c a u s e d b y v a r i o us s a l t s i n p e r i me n t a l p oc r e d u r e a r e d e s c r i b e di ". T h e i n t e na r l e t h a n o l - wa t e r a z e o t op r e ` ' a n d v a r i o u s n o n v o l a t i l e s o l - pr es s u r e o f t h e s t i l l wa s ma i nt ai n e d a t c o ns t a nt v a l u e 0 0. 3 k P a) b y l i n k i n g a s e t o f p r e s s u r e s t a b i l i z i n g u t e s i n me t h a n o l - a c e t o n e - c h l o of r o r m e m e o t op r e " i . I s i t (1 o f u ni v e r s a l s i g n i f i c a n c e ? Th i s c o nc l u s i o n wa s p r o v e d t o b e t r u e i n t h i s p a p e r b e c a u s e i t n o t o n l y c a n b e d e r i v e d f r o m t h e r mo dy n a mi c s, b ut a l s o c o n s i s t s wi t h a l l kn o wn e x p e r i me nt a l r e s u l t s . 2 Ex pe ime r nt al a pp a r a t u s a n d mo ni t o r e d b y us i n g a di g i t a l di s pl a y ba - r o me t e r . The bo i l i n g p o i nt o f mi x e d s o l v e nt wa s me a s - u r e d b y u s i n g a me r c u y- r i n- g l a s s t h e r mo me t e r(1 /1 00 ( : d i v i s i o n s ) a n d t h e e l e v a t i o n o f a z e o t r o p e ' s b o i l i n g p o i n t b y us i n g t he Be c kma n n t he r mo me t e r . Th e e qu i l i b r i u m v a p or c o mp o s i t i o n wa s d et e r mi ne d b y me a n s o f r e f r a c - *P r o j e c t s upp or te d by t he s c i e nc ea n d t e c h n o l o g y c o mmi t t e e a n d t h e e d u c a t i o n c o mmi t t e e o f He n a n p r o v i n c e 3 kr T o wh o m c o r r e s p o n d e n c e s h o u l db e a d dr e s s e d, E- ma i l ; t y. s u n @ 2 6 3. n e t Rec ei v ed da t e一2001 05- - 2g 万方数据 化 304 学 物 理 学 第1 5卷 报 t h - st artc omposat on at9tven pressu le az eot r opewi I t y pe wi t h a c c u r a c y o f 0. 00 03 wa s us e d. The a z e o - t r o p i c c o mp o s i t i o n o f me t h a n ol - t e t r a h y d of r u r a n bi n a y r l i q u i d mi x t ur e wa s o b t a i n e d b y me a n s o f me a s ur i n g x- c u r v e. Th e b i n a r y s o l ut i o n' s v a p o r - l i q u i d e qu i l i b r i u m da t a we r e d e e me d t he r mo dy na mi c c o n s i s t e n t b y t h e He i i ng t o n me t h o d. t heCi bbs Duhem 助 些 t i on mea s ur eme nt s, a nd an . Abbe r e f r a c t o me t e r o f WZS- x RT as f ol l ows o f l i qui d pha s eis 十 二 d R A T ,= H , _ (I) 了 了万口t R了 ‘ -- s ubs c r i pt s i a nd s r epr e s e nt a c o mp onentof a n d n o nv o l a t i l e s o l ut e, r e s p e c t i v e l y;x i s t he f r a c t i o n o f c o mpo ne n t m azeotrope calculated x 2. 3 Res ul t s Tl i e VLF : da t a o f me t h a no l - t e t r a h y dr of ur a n a z e o - t op r e a n d t h e c o mp a r i s o n wi t h t h e l i t e r a t u r e v a l ue a r e , hown i n Tabl e 1. The dat a of i nf luenc e of 1 0 nonv ol a- i s a n d x, ( i= ]_K) o n s o l u t e - f r e e b a s i s , s o工x=I e t oa c o ns t a n t ; x, i s t h e mo l e r a t i o o fsolut z e ot r o pe; H i s t h e e n t ha l p y o f s o l ut i o n c o n t a i n i n g 1m o t a z e o t r o p e S u p p o s e t h e c h e mi c a l p o t e n t i a l s o f c o mp o n e n t i a n d -I - t e s , v i z .,, u } a n d p t,ma y b e r e p r e s e n t e d b y f u g a c i t y t u r a n a z e o t r o p e a r e g i v e n i n Ta b l e 2, i n wh i c h t h e e x - a 关a n d a c t i v i t y a,r e s pe c t i v e l y, i t f o l l o w s t h a t p l a n a t i o n o f[ Y] a n d[ A ] s t a y i n g b e h i n d. 7 L二F L ' i ( T)+R TI n f ,( 。二I一K) ( 2) I ' a b l r I Va p o r - l i q u i d e q ui ib l r i u m d a t aj-t h . . . 1 , k =W.( T, 尸)十RT 1 n a , ( 3) t r t 汕v dn而种 2- 1 .甲e B y s u b s t i t u t i n g Eq. ( 2)a n d( 3)i n t o Eq.(1)a n d 之 /1几 PA P. T日k巴门I - c o mbi ni ng wi t h 60. as 1m 3 t i l e s o l u t e s o n t he b o i l i ng p o i nt o f me t h a n o l - t e t r a h y d r o - = a } ( 4 r 7 } 6 ) 0.476 I li . P叩e r 60 82 H。 一 H. dx.十 一一二二 二不万一d7' (4) d l n a二{ 垫 1 01_3 \ax Rl ‘ wher e H0,a nd H, ar et h e mo l a r e n t h a l py o fsolute at 3 Di scussi on t at e and sl anda司 s p a r t i a l mol a r e n t h a l p y , t h i t a s t 3. 1 The r modynami c c ons i de r at i on r espeo l i v e l y. I t i s f o u n d ki nd of nonvol at i l e s ol ut e di s s ol v es i n an W h T e A n l 1 , e 2 1 0 . . . . . o f 1 0 n o n v o l a t i l e s o l u t e s o n b o i l i n g p o i n t o f me t h a n o l , - t e t r a h y d r o f u r a n 2 a z e o no p e( :=0. 47 6, P二1 0 0. 3 k P a) S o l u t e :・1 0 2 y , pT /K 一[ Y] [ A]一 ’・t o , S o l ue f r e e 0 0. 4 76 0 I J口 二・t o , y , pT / K 一_ YI [ . 4[’・1 0 2 Sol ut e f - 0 0. 476 0 1. 03 0. 458 0.1 48 1 2.1 2 KOH 1. 04 0. 442 0.104 39. 70 2.06 0.429 0.330 27.14 2.08 0. 41 9 0.250 49.1 6 3. 08 0.398 0. 520 41.11 3.1 2 0.379 0.41 0 57. 78 Cuf : l 2 0. 98 0. 471 0. 078 2. 55 Nat 0.1 0 0. 450 0.060 钧 21 1. 96 0. 肠 5 0.1 80 4. 31 0.20 0. 429 0.1 20 52.1 8 2.94 0. 459 0. 324 5. 38 0.30 0. 403 0.I 98 61. 68 KI 0.44 0. 472 0. 038 3.59 C. Cl i 0.1 0 0. 44 9 0. 0 9 4 引4 6 0.88 0.466 0.088 7.30 0.20 0. 429 0.1 90 41. 加 1. 32' 0.肠 ] 0.1 24 10.47 0.30 0.41 0 0.258 49. 71 NH,N0, 0. 68 0. 4 72 0. 0 44 2. 79 Hg Br z 0. 81 0. 480 0. 03 4 1 . 90 1.37 0.467 0.076 6.37 1. 62 0. 482 0. 056 2. 48 2.05 0.462 0.132 7.84 2. 43 0. 483 0. 078 2. 83 Na Br 0. 36 0. 469 0. 03 6 9.11 Hg Cl i 1 . 01 0. 48 6 0. 0 9 0 5. 3 8 0. 72 0. 461 0. 070 1 6.38 2. 02 0. 497 0.184 11.00 1. 08' 0. 457 0. 088 1 9.89 3.03 0. 51 0 0. 336 1 4.43 甲 Snwr .l rd 万方数据 Sd w。 孙仁义等:非挥发性溶质对共沸物沸点的影响 第 4期 a a l n x a ,r 少 . d x ,K \H R T z( ' ) d T” 叉x , d I n f ,+尤 ・ wh e r e A, H, i s t h e pa ti r a l mo l a r v a p o r i z a t i o n e n t ha l p y o f c o mp o n e n t i . Un d e r c o n di t i o n o f v a p o r - l i qui d e q u i l i br i - 飞05 s h o u l d b e x.Th i s i mp l i e s!A] IG 〔 ‘ } ・ 〔 ‘ 卜丁 ) ( A ・ ‘ ' } R ' 0 V H ' l 1 d T 。 Y 卜A ] = Y F - 1 x ; l n Y ' , ( 6) y del e sul t i s as f ol l ows I Y , t her x z , ( △,) 2、 9) a re 〔 Y ] = } - x Y ' , A y .芝 倒 r e l a t i o ns hi p i n t o Eq. ( 5) a n d i n t e g r a t i ng Eq. ( 5) x. 二0 t o x, ,r e c a l l i n g二(I=I一K) a n d P a l l const ant a nd ( p , ma y b e t a ke n a s c o n s t a n t a p p r o x i ma t e s m l a a r g l l e As t o〔Y],l e t Ay二y 卜 y,t h u s【Y; c a n b e t a k e n a s a f u n c t i o n o f Ay , t h r o u g h s e r i e s e x p a n s i o n 1 12 va por pha s e ns e ti r ng a - i t s f ug a ci t y c o e f f i c i e nt , r e s pe ct i v e l y I a in amount of t he s a me o r de r as x, when x, i snot too f=f ' y } W . ,P, y,g y p ; r e p r e s e n t v a p o r ' s t o t a l p r e s - .t he mol e f r a ct i on o f c o mpone nt a F o r a z e o t op r e x二y, , a n d艺△,二0, t h e f i r s t ” t e r m o f A y ; i n Eq. ( 9 )i s e q u a l t o z e r o . Th e s q u a r e t e r m o f Ay , i s a l wa y s n e g a t i v e s o t h a t「Y]i s a s ma l l n e g a t i v e v a l u e . Ac c o r d i n g t o t h e p h a s e r u l e t h e n u mb e r o f d e g r e e s o f f r e e d o m i s e q u a l t o 1u n d e r t h i s c o n d i - (7) (8) t i o n, s o Ay , ma y b e eg r a r de d a s a u n i t a y r f u n c t i o n o f x , a nd mus t be p op r o ti r o na l t o i t a pp r o x i ma t e l y wh e n x s u p e r c r i p t s r e p r e s e n t s t h e s y s t e m c o n t a i n i n g n o n v o l a - t i l e s o l u t e. Eq. ( 6) i s t h e t he r mo d yn a mi c Eq. o f n o n- v o l a t i l e s o l u t e' s e f f e c t o n t he b o i l i n g p o i n t o f a z e o t r o p e. l o o l a r g e. Th e r e f o r e, t he s i g n o f t h e l e f t s i d e i n Eq ( 6) i s ma i n l y d o mi n a t e d b y [ A],i t mu s t b e p o s i t i v e t hi s i mp l i e s t ha t t h e b o i i l ng p o i nt o f a z e o t r o pe mu s t b e Si n c e t h e v a l u e i n t he p a r e n t he s e s o n t h e r i g h t s i d e o f e l eva t ed i n di l ut e s ol ut i on at l eas t . Eq. ( 6) i s p o s i t i v e, i f t h e s i g n o f t h e l e f t s i d e i s p o s i - 3.2 Di scussi on t i v e, t he b o i l i n g p o i nt o f c o n t a i n i n g no nv o l a t i l e s o l ut e s y s t e m, v i z .,T ` , mu s t b e h i g h e r t h a n t h a t o f t he s y s - t e m wi t h o u t a ny s o l u t e, v i z .,T, i n d t h e r wo r d s, t he b o i l i n g p o i n t mu s t b e e l e v a t e d. T h e e x p e r i me n t a l r e s u l t s i n Ta b l e 2 i n d i c a t e t h a t 1 0 no n v o l a t i l e s o l ut e s a l l c a u s e t h e b o i l i n g po i n t c l e v a - wher e [ A 卜f f J , x ' ( 弩 I r 产 i s n o t t o o l a r g e . Th i s me a n s Ay , i s a s ma l l a mo u n t o f t h e s a me o r d e r a s二,a n d(Ay) ’ o r [ Y] i s a s ma l l a - mo u n t o f t h e h i g h e r o r d e r t h a n x , o r [ A ] wh e n x , i s n o t t i o n o f me t ha n o l - t e t r a h y d r o f u r a n a z e o t r o p e, a l t h ou g h t h e v a r i a t i o n o f a z e o t r o p e ' s v a p o r c o mp o s i t i o n c a u s e d b y Hg Cl r a n d Hg Br z i s d i f f e r e n t f r o m t h e o t h e r s . Th e e x p e r i me n t a l r e s u l t s i n t hi s p a pe r a n d t he r e l e v a n t r e - A s f o r t h e s i g n o f【 A],i t d e p e n d s o n t h e s i g n o f p a r t i a l d i f f e r e n t i a l i n Eq . ( 8 ) . Ac c o r d i n g t o t h e mo d y - n a mi c s p, o r I n a , mu s t b e a n i n c r e a s i n g f u n c t i o n o f x , a t p o t r s i n t h e l i t e r a t u r e t 3 ' ' j a r e i n a g r e e me n t w i t h a b o v e c o n s t a n t t e mp e r a t u r e a nd pr e s s ur e. I f n o t s o, s o l ut e s h o ul d d i f f u s e f om r t h e l o we r c o n c e nt r a t i o n r e g i o n t o c o n c l us i o n wi t h o u t e x c e p t i o n. t h e h i g h e r o n e wh e n i t d i s s o l v e s i n a z e o t op r e, i t i s i m- p o s s i bl e. Th i s me a ns t h a t n o t o n l y t h e p a ti r a l d i f f e r e n- t i a l, 。Eq . ( 8 ),b u t a l s o t h e v a l u e o f[A]。 a l wa y s p o s i t i v e, a n d[ A3wi l l g e t mo r e a n d mo r e p o s i t i v e wi t h i n c r e a s i n g o f i n t e g r a t i o n l i mi t x.Al t e na r t e l y, a c c o r d - i ng t o t h e t h e o y r o f s o l ut i o n c h e mi s t y r t h e l o g a r i t h m o f a c t i v i t y c o e f f i c i e n t c a n b e r e p r e s e n t e d b y a p o we r s e r i e s t i o o f t he m wa s g i v e n i n t he f i f t h c o l um o f Ta bl e 2 i n o r de r t o ma ke c o mpa r i s o n b e t we e n t h e i r ma g ni t u de s S i n c e t h e s i g n o f [ Y] i s o p p o s i t e t o[ A],t h e r a - Th e c a l c u l a t i o n p oc r e d u r e i s a s f o l l o ws; f i r s t l y,[Y〕 wa s c a l c u l a t e d o u t a c c o r d i n g t o Eq. ( 7);t h e n, t h e i n - t e g r a t i o n o n t h e r i g h t s i d e o f Eq. ( 6) wa s c a l c u l a t e d b y a s s umi ng t ha t△ H ma y b e r e g a r d e d a s c o ns t a nt a nd r e p l a c e d wi t h t he mo l a r v a p o r i z a t i o n e n t h a l p y; f i n a l y, o f l i q u i d c o n c e n t r a t i o n",、 . e . ,a=x , e x p I f ( x , ) I . [A马wa s o b t a i n e d b y i n s e ti r n g t h e a b o v e r e s u l t s i n t o I n s e ti r n g a b o v e r e l a t i o n s h i p i n t o Eq. ( 8) a n d r e c a l l i n g Eq. ( 6). T h e mo l a r v a p o r i z a t i o n e n t h a l p y o f me t h a n o l f ( X)、 、a p o we r s e r i e s o f x,[A ] c a n b e r e d u c e d t o a n d t e l r a h y d r o f u r a n(t a k e n f r o m [ 6了)a r e 3 9 21 5 a n d t h e p o we r s e r i e s o f x , a n d t h e l o we s t o r d e r t e r m o f i t 2 7 6 5 6 J /mo l , r e s p e c t i v e l y . I t i s e v i d e n t t h a t工Y] i s 万方数据 化 学 物 理 学 第1 5卷 报 a l wa y s n e g a t i v e a n d i t s a b s o l u t e v a l u e d e c r e a s e s a t a at i l e sol ut e f om r t her mo dy na mi c s, i . e.,a l i t t l enonvol f a s t e r p a c e t h a n[ A] wi t h a p p oa r c h i n g o f x , t o z e o, r t h e r e f o r e,[A ] b e c o me s a p r i ma y r f a c t o r d o mi n a t i n g a l wa y s c a us e s t h e b o i l i ng p o i nt azeotr ope cr ea s e. By v er i f y i ng, i t was i n a gr e eme nt wi t h t he t h e v a r i a t i o n o f a z e o t r 叩e' s b o i l i ng p o i nt i n d i l ut e s o l u- p e r i me n t a l r e s u l t s i n t h i s p a p e r a n d t h e r e l e v a n t r e p o r t s t i on at l east . i n t he l i t e r a t ur e wi t hout e xc e pt i on. e m X - I n f a c t , t h e b o i l i n g p o i nt o f e a c h a z e o t r o p e i s s t i l l r a i s e d a l t h o ug h t h e me a n c o nc e nt r a t i o n o f 1 0 n o nv o l a - p o s s i b l e t h a t「Y] b e c o me s n e g a t i v e a n d i t s a b s o l u t e v a l u e i s mo r e t h a n t h e v a l u e o f[ A] e v e n i n d i u l t e s o - l o t i o n s i n c e t h e f i r s t o r d e r t e r m i n Eq . ( 9) ma y b e n o t z e o, r i n t h i s c a s e, t he a n o ma l o u s o f b o i l i n g po i n t de - p r e s s i o n wi l l o c c ur ca,sunGal ser sun 叫圈 t o t he n a r ow r r e g i o n wi t h o u t a n y p r a c t i c a l s i g n i f i c a n c e. As c o n c e ns r n o na z e o t opi r c mi x t ur e s, h o we v e r , i t i s lli Li uW B Wa ng J J, Zhu o K L, e t a l . Ac i a Ch i mi c a Si n i 叫匡 t i l e s o l u t e s r e a c h e s 0. 0 2 , i . e .,t h e me a n v a l u e o f x i s e q u a l t o 0. 0 2, h e n c e, t h e c o n c e n t r a t i o n o f n o n v o l a t i l e s o l u t e r e s u l t i n g i n b o i l i n g p o i n t e l e v a t i o n i s n o t l i mi t e d 56: 21 1 R 9 9 Y 8Chew. I己 d . En g. ( Ch i n a) 一 1 M 9 7 6 A 1 996, 47 4 C 0 h 1 - , R. Adv an La br a do r M D. Al v a r e zJ 155, 85 J. He - Uni v .,2002, 3 2: 26 Hu a n g Z Q I n t r o d u c t i o n o f No n e l e c t ol r y t i c a l S o l u t i o n Th e o y, r Be i j i n g Sci ence Pr es s [ 6] Ya o Y B, Xi e T,G助 t 1 y r 9 8 , 5 YM 1973. 4 Handh- k ofP h y s i c a l Ch e ni r s - Sh a n幼a iSc i e nc e a nd Te c h nol o g y Pr e s s 4 Concl usi on A c onc l us i o n o f uni v e r s a l s i g ni f i ca nc e wa s de r i v ed 非挥发性溶质对共沸物沸点的影响‘ 孙仁义 孙 茜 ( 河南大学化学化工学院,开封 4 7 5 0 01 ) 〔 华东师范大学化学系 上海 2 0 0 0 6 2) 摘 要: 测定了1 0种非挥发性溶质对甲醇 一四氢吠喃共沸物沸点的影响. 发现与共沸物平衡的气相组成 因非挥发性溶质不同发生了不同的变化, 但所有非挥发性溶质都引起共沸物沸点升高。运用热力学原理对 实验结果进行了讨论. 理论分析及对分析结果的实验检验表明, 少量非挥发性溶质总引起共沸物沸点升高是 一个具有普遍意义的结论. 关键词: 甲醇;四氢吠喃;非挥发性溶质;共沸物;沸点 中图分类号 064 5. 1 6 文献标识码 : A 河南省科委、 河南省教委资助项目. 通讯联系人,E- ma i l ; y. r s u n @ 2 6 3 . n e t 万方数据
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