Partial Molar Volumes of Aluminium Chloride, Aluminium Sulphate and Aluminium Nitrate in Water-rich Binary Aqueous Mixtures of Tetrahydrofuran

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1 ORIENTAL JOURNAL OF CHEMISTRY An Internatinal Open Free Access, Peer Reviewed Research Jurnal ISSN: 97-2 X CODEN: OJCHEG 214, Vl. 3, N. (4): Pg Partial Mlar Vlumes f Aluminium Chlride, Aluminium Sulphate and Aluminium Nitrate in Water-rich Binary Aqueus Mixtures f Tetrahydrfuran R.C.THAKUR 1 *, RAVI SHARMA 1, ASHISH KUMAR 1, SANJAY KUMAR 1 and M.L.PARMAR 2 1 Department f Chemistry, Schl f Physical Sciences, Lvely Prfessinal University, Punjab 3 Department f Chemistry, HPU Shimla, India. *Crrespnding authr rameshchandthakur@yah.c.in (Received: Octber 1, 214; Accepted: Nvember 2, 214) ABSTRACT Partial mlar vlumes f aluminium chlride, aluminium sulphate and aluminium nitrate have been determined in water rich binary aqueus mixtures f tetrahydrfuran (5, 1, 15, 2% by weight f tetrahydrfuran) with the help f density measurements. The density measurements were made by using Ward and Miller methd and results have been analysed by Massn s equatin and interpreted in terms f in-in r in slvent interactins. The partial mlar vlumes vary with temperature as a pwer series f temperature. Structure making r breaking capacities f aluminium salts have been inferred frm the sign 2 ф v T2 p i.e secnd derivative f partial mlar vlume with respect t temperature at cnstant pressure. The aluminium salts have been fund as structure breakers in binary aqueus mixture f tetrahydrfuran. Key wrds: THF, partial mlar vlumes, slutin chemistry, structure breaker, aluminium salts INTRODUCTION Partial mlar vlume is ne f the imprtant thermdynamic prperty which has been prved a very useful tl in determining the varius types f interactins like in-in, in - slvent and slvent slvent interactins ccurring in aqueus as well as nn-aqueus slutins 1-11.These interactins are very helpful in determining the structure and prperties f the slutins. On the additin f an rganic slvent t water, it brings a change in the slvatin f ins. Recently, appreciable wrk has been dne n thermdynamic prperties f varius electrlytes in different binary aqueus mixtures but studies f aluminium salts in binary aqueus mixtures f tetrahydrfuran are still missing. Hence, the present study seeks an attempt t understand the interactins f aluminium salts in water and THF+ water system.

2 238 THAKUR et al., Orient. J. Chem., Vl. 3(4), (214) EXPERIMENTAL The reagents, aluminium chlride, aluminium sulphate and aluminium nitrate were taken f AR grade. All these reagents were used after drying ver calcium xide desiccatr t keep them in dry atmsphere. Fresh triple distilled water was used as standard slvent fr preparing binary THF + water mixture. The density f dixane was fund gcm -3 at K, is in gd agreement with literature value f THF density value 12 (d = gm -3 ). The binary aqueus mixtures f tetrahydrfuran and six different cncentratins f abve mentined aluminium salts were prepared by weight and the cnversin f mlality (m) int mlar cncentratin(c) was dne by using the standard expressin: c = md1 1 + mm 2...(1) Where, d is the density f slutin and M 2 is the mlecular weight f aluminium salts. The density was measured with the help f an apparatus similar t the ne reprted by Ward and Miller 13. The accuracy in the density measurements was 1 x 1-4 gcm -3. The apparent mlar vlumes (v) were calculated frm the density data using the fllwing expressin 14 v= 1(d d) mdd (2) where d- is the density f THF +water as slvent and d is the density f slutin; c is the mlar cncentratin f aluminium salts and M 2 is the mlecular weight f aluminium salts. The density measurements were taken in a well stirred water bath with a temperature cntrl f ±.1 K. RESULTS AND DISCUSSION The measured values f densities f aqueus slutins f aluminium salts in different cmpsitins f THF + water (5,1,15,2%) at K, have been used t calculate the limiting mlar vlumes.the plt f verses c were fund t be linear with psitive slpes in different cmpsitins f THF + water. A sample plt fr aluminium nitrate in different cmpsitins f THF +water at 33.15K is shwn in fig.1 The limiting mlar vlumes v and experimental slpes * were calculated by using Massn equatin ф v= ф v +s v c 1/2...(3) Table 1 shws the values f and S *, v V calculated in different cmpsitins f binary aqueus mixture f THF at K. It is clear frm table 1, that the values f slpes (S V *) are negative in water as well as in THF+ water mixture at 33.15K in all the cmpsitins. The negative slpes values f aluminium salts, indicates the presence f weak in- in interactins. Als, frm Table 1, it is clear that the magnitude f S V *values f aluminium salts decreases with increase in the amunt f THF in water, which shws that in-in interactins are further weakened which results in the increase in slvatin. Als frm Table 1, it is clear that the v values are psitive and increase in magnitude, in all the cmpsitins f THF + water at 33.15K fr aluminium salts taken fr study. The values which v is a measure f in-slvent interactin increases fr each aluminium salts with the increase f THF amunt in water, shws that in- slvent interactins enhanced n the additin f THF in water which indicates that slvent has less affinity fr water. On cmparing the magnitudes f values with the values f, values are mre in magnitudes than that f f v the same aluminium salts. This cncludes that inslvent interactins dminate ver the in-in interactins in water + THF mixture at K. The vlume f transfer ( v ) has als been calculated by using the relatin: V = v(ms) v(w)...(4) Here V (MS) and V (W) are the partial mlar vlumes f aluminium salts in mixture f THF + water and water as slvents respectively. The values f vlume f transfer f aluminium salts were recrded

3 THAKUR et al., Orient. J. Chem., Vl. 3(4), (214) 239 in table 1.It is clear frm table 1 that the v values cntinuusly increase in magnitude with the increase in the cntent f THF in water. The increase in and v v may be trait t the decrease in electrstrictin in the presence f THF. The electrstrictin effect, which leads t the cntractin in the vlume f the slvent, is lwered in the mixed slvents as cmpared with that in pure water. This electrstrictin effect, again cnfirming the earlier cnclusin f lesser affinity f THF fr water. v values, fr each aluminium salts rise with the increase f THF amunt in water ; which may be trait t the decrease in slvent slvent interactins between THF + water. Since the behaviur f each electrlyte was fund t be linear and same in different cmpsitin f THF + water at K, s nly Table 1: Partial mlar vlumes ( ) and experimental slpes (s v* ) fr aluminium sulphate, aluminium nitrate and aluminium chlride in different cmpsitins f THF+water at k temperature Cmpsitin Aluminium Aluminium Aluminium f THF- Sulphate Nitrate Chlride Water (wt.% ) Sv* V tr Sv* V tr Sv* V tr (cm 3 (cm 3 lt 1/2 ( cm 3 (cm 3 (cm 3 lt 1/2 (cm 3 (cm 3 (cm 3 lt 1/2 ( cm 3 ml -1 ) ml -3/2 ) ml -1 ) ml -1 ) ml -3/2 ) ml -1 ) ml -1 ) ml -3/2 ) ml -1 ) Table 2: Partial mlar vlumes ( ) and experimental slpes (s v* ) fr aluminium sulphate, aluminium nitrate, aluminium chlride in 5% (w/w) thf+water at different temperatures Temperature Aluminium sulphate Aluminium nitrate Aluminium chlride (k) * * * (cm 3 ml -1 ) (cm 3 lit 1/2 ml -3/2 ) (cm 3 ml -1 )(m 3 lit 1/2 ml -3/2 ) (cm 3 ml -1 ) (cm 3 lit 1/2 ml -3/2 ) Table 3: Partial mlar vlume expansibilities ( e ) fr aluminium sulphate, aluminium nitrate and aluminium chlride in 5% (w/w) thf + water mixture at different temperatures Temperature(k) Aluminium sulphate Aluminium nitrate Aluminium chlride E ( cm 3 ml -1 K -1 ) E ( cm 3 ml -1 K -1 ) E ( cm 3 ml -1 K -1 )

4 24 THAKUR et al., Orient. J. Chem., Vl. 3(4), (214) ne cmpsitin system (5% w/w) has been selected fr studying the effect f temperature. The experimentally determined values fr the different cncentratins f aluminium salts at different temperatures (298.15K K) have been used t calculate the limiting mlar vlume f the salts. The plt f apparent mlar vlume v against c were fund t be linear with the psitive slpes in water as well as in aqueus slutin f THF as shwn in fig. 2 fr ne f aluminium salts (aluminium nitrate) as sample plt. Fig. 1: Plt f Vs c 1/2 f aluminium nitrate in different cmpsitins f THF + water at 33.15K Fig. 2: Plt f Vs c 1/2 fr aluminium nitrate in 5% binary mixture f THF + water at different temperatures It is evident frm table 2, that the values f * are negative fr aluminium salts in 5% aqueus mixture f THF at all temperatures. The negative values with rise in temperature frm K t K f aluminium salts indicates the presence f weak in-in interactins and attributes the increase in the slvatin f aluminium salts with rise in temperature. Als it is clear frm table 2 that the values f increases with increase in temperature fr the selected aluminium salts in THF + water (5% w/w),thereby shwing that in slvent interactins are strengthened with increase in temperature. The increase in values may be due t increase in slvatin f aluminium salts with rise in temperature. It has been fund that nly is nt nly ne parameter fr determining the structure making r structure breaking nature f any slute. Partial mlar vlume expansibilities is anther parameter, which determines the making r breaking capacity f any slute in any f the slvent develped by Hepler 15. The temperature dependence f 5% THF + water fr selected aluminium salts can be expressed by the fllwing relatins: = T -.26T 2 fr aluminium sulphate...(5) = T -.2 T 2 fr aluminium nitrate...(6) = T -.27 T 2 fr aluminium chlride...(7) Fig. 3: Plt f E verse temperature fr aluminium sulphate, aluminium nitrate, aluminium chlride in 5% THF + water Partial mlar vlume expansibilities E = P, which is temperature dependence

5 THAKUR et al., Orient. J. Chem., Vl. 3(4), (214) 241 functin f,is calculated fr the abve mentined aluminium salts by using relatins 5,6 and 7 are given in table 3. Frm table 3, D E values fr aluminium salts at different temperatures are psitive but decrease in magnitude with rise in temperature shwing that these aluminium salts are nt behaving like symmetrical tetra alkyl ammnium salts 16 and but like cmmn salts 17,18 as in the case f cmmn electrlytes the mlar vlume expansibilities shuld decrease with the rise in temperature. The decrease in the magnitude f D E values indicates the absence f packing effect 15. The plt f D verses temperature is fund t be E linear fr all aluminium salts in 5% w/w THF + water mixture as shwn in fig.3. In last few years, it has been bserved by the number f wrkers that is nt the nly criterin fr determining the structure making r breaking nature f any slute. Hepler 14 has given a methd f finding the sign f fr different types f slutes in frms f lng range structure making r structure breaking capacities f the slutes in aqueus slutins using the general thermdynamic relatin: ( )/ ) = (8) On the basis f equatin 8, It has been fund that the psitive values indicates the structure making nature f slutes and negative values indicates the structure breaking nature f slutes. In ur present study, it is fund frm equatins 5 t 7, values are negative fr aluminium salts in 5% THF + water suggests that the all the aluminium salts taken in present study act as structure breakers in 5% aqueus slutin f THF. This indicates that the additin f aluminium salts break the structure f THF + water. REFERENCES 1. Parmar M L,;Banyal D S,; Indian J Chem, 25, 44A. 2. Parmar M L,; Guleria M K,; J Indian ChemSc, 25, Parmar M L,; Thakur R C,; Prc. Nat. Acad. Sci. India., 26, Parmar M L,; Thakur R C,; J Ml Liq., 26, Parmar M L,; Attri S C,; J Ml Liq, 27, Sarkar B K,;Sinha B,; Ry M N,; Russian J f Physical Chem, 28, Bhattaraiand A,:Das B,; J. Nepal Chemistry, 29, Yusuf M A,; Salim Reza K M,; Daffdil Internatinal University J f Science and a. Technlgy, 29,4. 9. Rajagpal K,;Gladsn S E,; J. Chem.Thermdynamics 211, Shashi Kant,;Sharma Kamini,; ChemSci Trans,(212) 11. Singh, R.; Yadav, Y.; Orient.J.Chem, 213,29(4), Cvintn A K,;Dickisn T, Physical Chemistry f Organic Slvent Systems, a. (Plenum, New Yrk) Ward G K,;Miller F J,; J Chem 1974., Miller F J, in structure and Transprt Prcesses in water and Aqueus Slutin, a. edited by R A Hrne, (Wiley inter Science, New Yrk) 1971, chap. 13, p Hepler L G,; Can J Chem 1969., Miller F J, in structure and Transprt Prcesses in water and Aqueus Slutin, a. edited by R A Hrne, (Wiley Inter Science, New Yrk) 1971, chap.15, p Milller,F.J.; Drst Hansen, WJ.P phy.chem.72.(1968) 18. Miller F.J,; Chem.Rev 1971,.71.