Ttle The solubltes of compressed acet solublty of compressed acetylene Author(s) Kyama, Ryo; Hraoka, Hroyuk Ctaton The Revew of Physcal Chemstry of Issue Date 1956-8-3 URL http://hdl.handle.net/2433/46734 Rght Type Departmental Bulletn Paper Textverson publsher Kyoto Unversty

The Revew of Physcal Chemstry of Japan Vol. 26 No. 1 (1956) THE SOLUBILITIES OF COMPRESSEfl ACETYLENE GAS IN LIQUIDS, The Solublty of Compressed Acekylene Gas n Tetrahydrofuran* IV HY RYO KIYAM AND IlIROYUKI HIRAOKA Inkroduckon In the prevous papers, the authors reported the solubltes of compressed acetylene gas n wa±er'>, methanol-' and benzene' and found that the solublty of acetylene n water at lugh pressures deva*.es nega±vely from Henry's law n the from N,=kP, where N: s the mole fracton of acetylene, P the partal pressure of acetylene and k a constant and the solublty s nearly proportonal to the fugac[y of acetylene, whle the solubhtes n methanol and n benzene a± hgh pressures devate postvely from Henry's law and moreover the soluton of benzene shows the postve devaton from Raoult's larv and ths devaton cottld be well explaned on the bass of the theory of regular solutons wth the Flory-Huggns entropy correcton arsng from the dfference n the nrolal volumes of the two substances. In the present paper, the solublty of acetylene n tetrahydrofuranhavng an electronegatve oxygen atom n the molecule, a donor solvent for acetylene, n the range of temperature from to 3 C and up to pressure 3 kg/cm', whch has been never measured, s reported and rather qualtatve consderatons upon the characterstcs of acetylene solutons are gven. I Expermentals Tetrahydrofuran used as the solvent s fractonated by dstllaton, after refluxng wth metallc sodum for several hours and a porton wth bolng pont 66.166.3 C (76 mmhg) s taken, and ts vapor pressure measured wth an sotenscope n the range of6 to 76 mmhg and ts densty from 5 to 3 C are represented by Eqs. (1) and (2), respectvely, dr=.979-9.93x1-"t-1.6x1-et (1) loge Pr=-122x1-'+,5.635.t+2~5, (2) where P, s n mmhg and t ~n degrees centgrade. ` Ths ncesgaton lras been dare by A. Itraoka, beng n fhe postgraduate course, under the d recfou of Prof. R. lcyarna. 1) H. Hraoka, Ths journal, 24, 13 (1954) 2) R. Kyama and H. Hraoka, bd., 25, 16 (1955) 3) R. Kyama and H. H'vaoka, bd., 25, 52 (1955)

The Revew of Physcal Chemstry of Japan Vol. 26 No. 1 (1956) 2 R. Kyama and H. Hraoka Acetylene used as the solute and the expermental procedures for the present measurements are all the same as those descrbed n the prevous reports. Resultr The vapor pressure and densty of tetrahydrofuran at each temperature used n the calculaton of the solublty are represented by Eqs. (1) and (2) and the coeffcents of dlataton by the absorpton of acetylene n tetrahydrofuran are assumed to have the same valve as n acetone'i because the data n tetrahydrofuran are lackng and the dfference among the values n the other solvents s comparatvely small f the solvents are lke one another,* and the correcton of the solublty due to the dlata+on s small. Table 1 Solublty of acetylene n tetrahydrofuran at one atmosphere Temperature, C Bunsen's coeh. 5 3.1 1 26. 15 22.? 19.5 25 17.3 The solublty of acetylene n tetrahydrofuran at one atmospherc pressure s gven n Table 1 and represented by Eq. (3), log, N_=8.85~x 1'_4.155 (3) where N_ denotes the mole fracton of acetylene and T the absolute temperature. In Tables 2 and 3, the solublty ofcompressed acetylene gas n tetrahydrofuran s gven n the mole fracton of acetylene and the numbers of cc of acetylene (S. T. P.) Table 2 Solublty of zcetylene n tetrahydrofuran (mole fracton of acetylene, N_) Press., Temp. C kglcmp 1 2 3 I 5 1 15? S U.341.519.237.439.691.231.369.491.595.74.192.323.433.532.613 s acetylene 4) Ths wll be confrmed n [he followng paper n whch tbe partal molal volumes of n varous solvents wll be reported. J. Horut, Sr. Posers Inst. Phys. Ctem, Resemch, Tokyo, ]7. 125 (1931)

The Revew of Physcal Chemstry of Japan Vol. 26 No. 1 (1956) The Solubltes oi Compressed Acetylene Gas n Lquds, IV 3 Table 3 Solublty of acetylene n tetrahydtofuran Temp., C Press., kg/cm= a ~.a 5 1~ 112 ~.~ 64~ 1 296 217 ~~ 129 15 2 25 617 264 42 649 27 37 929 o.~.e 25kB' " zok os ~~ T N n O.a O C oa g ~ 'C to C C 2'C L6 1A 2` s 2 1. 15k8/~^' 1 ykflj.7 ~a~` ~.8 5 1 15 2(1 33 3A 35 3.6 Partal p ssurc of acetykoa kg/cm' I /T ~ 1' Fg. L Solublty of acetylene n tetrahydro- Fg. 2 Logarthm of mole fracton of acetylene furan as functon of partal pressure ploted aganst recprocal of absolute of acetylene temperature contaned n 1 cc of tetrahydrofuran, respectvely. In Fg. 1, n whch the mole fracton of acetylene s plotted aganst thepartalpressure of acetylene, t s observed that the solublty at hgh pressures devates negatvely from Henry's law n the form N.,=kP and Fg. 2 shows that a nearly lnear relatonshp exsts between the logarthm of the mole fracton of acetylene and the recprocal of the absolute temperature at each pressure wthn the temperature range of the present nvestgaton. The converson of the total pressure to the partal pressure of acetylene has been made usng Dalton's law, and the mole fracton of tetrahydrofuran n the gaseous phase calcular_ed accordng to the method developed by Robn of nl., whch s descrbed later-

L V The Revew of Physcal Chemstry of Japan Vol. 26 No. 1 (1956) 4 R. K}ama and H. Hraolsa Consderatons The authors have measured the solubltes of acetylene n water, methanol, benzene and tetrahydrofuran and these solubltes aze classfed nto two cases n vew of the effect of the partal pressure of acetylene. One s the case n whch the solublty at hgh pressures devates postvely from Henry's law and the other the case n whchthe solublty :devates negatvely. The solubltes n methanol and n benzene belong to the former and those n water and n tetrahydrofuran to the latter, as s seen from Fg. 3 n whch the mole fracton of acetylene s plotted aganst the. partal pressure of.acetylene. In the latter case. t s notable that the solublty n water s exceptonally low and proportonal to the fugacty of acetylene and the solublty n tetrahydrofuran s the hghest among those n these solvents used and ffty tmes as hgh as the mole fracton of acetylene n water at 2 C and 2 kg/cm=. It may be consdered that the solublty of acetylene n alcohol or n nonpolar solvents n general belongs to the former and the solublty of acetylene n donor solvents or n water to the latter, when the solublty s represented by the mole fracton of acetylene. -~ hfethanol.5 TecrahYdMfuran os 2 OS Y b T Q Q Bemene t ~_ os y Water Pamrene `c.~ 3 Sfethanol `o ='.4 <`.2 Tetrahvdrofuran Wafer o s o t; zo zs an o oz o.a ob oa partal Dressure of acetylene: kgrem' h7ole franon of acetykne..h4 Fg. 3 Solublty of acetylene as functon of Fg. 4. Actvty of acetylene plotted aganst partal pressure of acetylene at ~ C mole fracton of acetylene at 2 C Now, pure lqud acetylene n equlbrum wth ts vapor at each temperature s chosen as the standard state of acetylene n the lqud soluton, then the actvty of acetylene n the lqud soluton n equ]brum wth the gaseous phase s equal to the rato of the fugacty of acetylene n the soluton [o that n the pure lqud state. The futlacty of pure acetylene s already reported and the concentraton of the

J The Revew of Physcal Chemstry of Japan Vol. 26 No. 1 (1956) The SolubIl[es of Compressed Acetylene Gas n Lquds, IV 5 lqud solvent n the gaseous phase necessary to the calculaton of the fugacty of acetylene n solutons s assumed to be approxmately computed by Eq. (4) accordng to Robn et al.~, log ~ n ~-(A+131T)P (4) where m s the mass of the lqud solvent per 1 cc of the gaseous phase of densty p n Amagat unt and ara the mass of the lqud solvent contaned n 1 cc of the gaseous phase n the absence of the compressed gas. shown n the table. The constants n Ey. (4) are System A A acetylene-water -.187 2.45 acetylene-methanol -.234 2.1 acetylene-benzene -.544 5.75 acetylene-tetrahydrofuran.16 In [he last system, acetylene-tetrahydrofuran. the frst term A on the rght hand sde of Eq. (4) contans only the contrbuton by the Poyntng effect, and the second term s taken nto no account because the approprate physcal constants of Letrahydrofuran necessary to the calculaton are unavalable. Then the fugacty of acetylene n solutons n equlbrum wth the gaseous phase s calculated as an approxmaton usng Lews-Randall's law, f =f_ N_, where. f., s the fugacty of acetylene n the soluton and f_ the fugacty n the pure state. 1'he dfference between the value of the fugacty thus obtaned and the value under the assumpton that the gaseous phase s pure acetylene s consderable at hgh temperatures and low pressures, but the dfference s only slght at low temperatures and hgh pressures. Fg. 4, n whch the actvty of acetylene n each soluton at 2 (; s plotted aganst the mole fracton of acetylene, shows [hat the postve devatons from Raoult's law are found n the souton of acetylene n water, methanol and benzene, whereas the negatve devaton n the soluton of acetylene n tetrahydrofuran, In the dscusson of the solutons of compressed gases, the change of free energy or actvty wth pressure mus*_ be taken nto account and ths change s related by the well known thermodynamc equa~son to the partal molal volume of the solute n solutons. In the followng paper the authors wll report on the measurements of the partal molal volume of acetylene n the wde range of concentraton n the varous solvents. So, n the present paper qualtatve consderatons about the characterstcs of acetylene solutons may be rather gven n the followng. Acetylene-toater system As mentoned prevously, the solutons of acetylene n wa*.er, alcohol and nonpolar solvents, such as benzene, devate postvely from Raoult's law. Among t4zm, aqueous I ~ 5) S. Robn et B. Vodar, J. Fhys. e! Fad.,.13, 264 (1952)

The Revew of Physcal Chemstry of Japan Vol. 26 No. 1 (1956) 6 R. Kyama and H. Hraoka soluton shows the lazgest postve devaton and Fg. 5 ndcates that the sotherms of the. actvty aganst the mole fracton at 2 C and 3 C are Imear and nearly concde wth each other but the actvty at a low temperature gradually decreases from the 37 K 3UC O.f v temperature _T 1 C o Q4 T 1 C 2 C G os.~ 1'C 3 C ~a~ OAW OA1.15 ~2D ttolo frazton of acetylene,,~, Fg. 5 Actvty of acetylene n water plotted aganst mole fracton of acetylene values at 2 C and 3 C, These ndcate that the heat of sohtton of lqud acetylene n water s negatve, that s, exothermc and the excess partal molal entropy of soluton has a lazge negatve value. The assumpton I ~1 that the rare gases and hydrocarbon gases form "ceberg" when they dssolve n cold water and that those molecules n soluton may be surrounded by orented cages of water molecules, gves a fne nterpretaton for the characterstcs of aqueous soluton of acetylene and t s ohserved that the sotherms at temperatures hgher than the crtcal temperature of the hydrate of acetylene, whch s obtaned from the cross pont of the vapor pressure of acetylene and that of the gas hydrate and s equal to 16 C ~, would neazly concde, whereas the sotherms at lower temperatures are drawn lower wth decreasng temperatures and from ths the partal molal heat capacty of acetylene n aqueous soluton s supposed to be large at lower temperatures. Acetylene-metlrauol system Acetylene methanol system shows a postve devaton from Raoult's law, as a net result of varous factor, the assocaton of methanol, the dfference n the nternal pressures of the two substances, the nteracton of methanol and acetylene, the dfference n the molal volumes of the two substances and so on. The temperature 6) H. S. Frank and M. N. Evans, J. Chem. Phys., 13, 57 (19x5) 7) W. F. Clauesen and M. F. Polglase, J. Am. Chem. Soc., 74, 9817 (1952) 8) M. V. Stackelberg and H. R. Muller, Zet. Efectracheme, 58, 25 (1954)

a The Revew of Physcal Chemstry of Japan Vol. 26 No. 1 (1956) The Solubltes of Compressed Acetylene Gas n Lquds, 1V 7 coeffcent of the actvty of acetylene n methanol s postve, as shown n Fg. 6, so that the hear_ of soluraon of lqud acetylene n methanol s negatve n accordance wth Mcntosh's observaton's of the formaton of a crystallne compound of acetylene and alcohol at lots temperatures. Acetylene-benzene sysfe»z In the prevous paper, the authors reported that the soluton of acetylene n benzene shows a postve devaton from Raoult's law and ths devaton could be explaned on the bass of the theory of regular solutons wth the Flory Huggns entropy correctons arsng from the dfferences n the molal volumes of the two substances. Moreover the temperature coeffcent of the actvty of acetylene s negatve, so that the heat of soluton of lqud acetylene n benzene s postve, that s, endothermc n accordance tv*1t the theory of regular solutons, although the heat of soluton of gaseous acetylene n benzene s of course exothermc owng to the condensaton of the gas. It may be consdered that ths nterpretaton may be applcable to other solutons of acetylene n nonpolar solvents. so os ~~ P/ %'. ~/ as s OA ~r: ~.; 'C as OA a d T.' :'~ ~/ 2 2 Acetone solutm at 3C Mok framonof aoetykoe. N 2 OA Ob OS Fg. 6 Actvty of acetylene n methanol plotted aganst mole fracton of acety]ene temperature C x 1 C p ZO C O 3 C Fg. 7 Mole (racoon of acetylene, N. 2 OA.6 OB Actvty of acetylene n tetrahydrofuran plotted aganst mole fracton of acetylene temperature C x ] C ~ 2 C O 3 C 9) D. Mcntosh, j. Phys. Chem., 11, 36 (197)

I The Revew of Physcal Chemstry of Japan Vol. 26 No. 1 (1956) S R. Kyama and H. Hraoka I Acetylene tetrahydrafaran sys[en: Tetrahydrofuran has an electronegazve oxygen atom n the carbon chan of the molecule whch has electrons that are avalable for hydrogen bond formaton wth the proton of acetylene. Studes on the solubltyof acetylene n such a donor solvent havng an actve center have been made extensvely from the techncal pont of vew, but those under hgh pressures are comparatvely few. 1'he solublty of acetylene n acetone measm~ed by Holemann e a1,.1> changes n the same manner as n tetrahydrofuran wth pressure. Fg. 7, n whch the actvty of acetylene s plotted aganst the mole fracton of acetylene, shows that the negatve de~~aton from Raoult's law n the soluton of acetylene n tetrahydrofttran s slghtly smaller than that n the soluton of acetone obtaned from the data by Holemann e! al. and the temperature coeffcents of the actvty of acetylene n both solvents are postve, ndcatng that the heats of soluton n such donor solvents are negatve, that s, exothermc and the strong specfc nteracton between acetylene and donor solvent molecule may be expected n accordance wth the assumpton of hydrogen bond formaton between the electronegatve atom n the donor solvent and the proton of acetylene. Part of the present measurements has been done by Mr. N. Yoshda. The authors are ndebted to the Department of Educaton for the Grant n Ad for the Fundamental Scentfc Indvdual Research (1'he Yhysco-Chemcal Researches on Acetylene). The Laboratory of Physcal Chemstry, Kyoto Unversty 1D) P. Holemann and R. Ilasselmann. Clrem. ng. Teclmk, 25, 4t6 (1953)