Avances en Química ISSN: Universidad de los Andes Venezuela

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1 Avances en Química ISSN: Universidad de ls Andes Venezuela Gmaa, E.; Hamada, M.; Galal, R. Apparent Mlal Vlumes f Sdium Fluride in Mixed Aqueus-Ethanl Slvents Avances en Química, vl. 5, núm. 2, may-agst, 2010, pp Universidad de ls Andes Mérida, Venezuela Available in: Hw t cite Cmplete issue Mre infrmatin abut this article Jurnal's hmepage in redalyc.rg Scientific Infrmatin System Netwrk f Scientific Jurnals frm Latin America, the Caribbean, Spain and Prtugal Nn-prfit academic prject, develped under the pen access initiative

www.saber.ula.ve/avancesenquimica Avances en Química, 5(2), 117-121 (2010) Artícul científic 117 Apparent Mlal Vlumes f Sdium Fluride in Mixed Aqueus-Ethanl Slvents E.

cm Recibid: 16/02/2010 Revisad: 30/04/2010 Aceptad: 28/08/2010 ------------------------------------------------------------------------------------------------------------------ Resumen: Las

2 Avances en Química, 5(2), (2010) Artícul científic 117 Apparent Mlal Vlumes f Sdium Fluride in Mixed Aqueus-Ethanl Slvents E. Gmaa*, M Hamada and R Galal Department f Chemistry, Faculty f Science, Mansura University, Mansura, Egypt (*) eahgmaa@gmail.cm Recibid: 16/02/2010 Revisad: 30/04/2010 Aceptad: 28/08/ Resumen: Las densidades de diferentes cncentracines mlales de flurur de sdi en mezclas de etanl/agua cm slvente han sid medidas sbre el rang ttal de cmpsición a tres temperaturas diferentes: 293,15; 303,15 y 313,15 ºK. De las densidades medidas ls vlúmenes mlales aparente y límite de ls electrlits han sid evaluads. Ls vlúmenes mlales límites para ls ines sdi y flurur fuern estimads pr desdblamient de las cntribucines iónicas cn una asunción asimétrica Palabras clave: Vlumen mlal aparente; Vlumen mlal parcial; Asunción asimétrica; Flurur de sdi. Abstract The densities f different mlal cncentratins f sdium fluride at ethanl-water mixtures, as slvent, have been measured ver the whle cmpsitin range at three different temperatures, , and K. Frm the measured densities, the apparent and limiting mlal vlumes f the electrlytes have been evaluated. The limiting mlal vlumes fr sdium and fluride ins were estimated by splitting the inic cntributins as an asymmetric assumptin. Keywrds: Apparent mlal vlumes; partial mlal vlumes; asymmetric assumptin; sdium fluride. Intrductin: The vlumetric behaviur f electrlyte slutins is an imprtant parameter fr studying in-slvent interactins as well as equilibria ccurring in the slutins. The limiting apparent mlar vlumes f an electrlyte at infinite dilutin crrespnd t standard partial mlar vlume 1. The partial mlar vlume f an inic slid can be splitted int its inic cntributins cmpunds 2. A simple alternative methd is t emply a reference electrlyte, like tetralkylammnium salt, whse ins are equal in size and d nt have any slvatin effects. Anther reference electrlyte is tetraphenyl-phsphnium tetraphenylbrate (Ph 4 PBPh 4 + TPTB - ) 1. The aim f this wrk is t evaluate the partial mlal vlumes fr sdium fluride and their inic cntributins in mixtures f ethanl-water as slvent Experimental Sdium fluride 99%, frm Aldrich Chemicals, was used. Abslute ethanl, frm Al-Gmhria Supplements, was used and it was used withut further purificatin. In general, densities f NaF in mixed ethanl, water and their mixtures were dne by measuring specific cncentratins and their dilutins using weighing bttle (1 ml) with capillary precalibrated by means f bidistilled water. The deviatin f the data is ± g. The slutins were put in a water bath Assistant 3193 fr at least 3 hurs. Fur digital weighing balance (Mettler 240) was used in all weighing prcedures. Results discussin The experimental densities (d) f dilute slutins f sdium fluride at different cncentratins in the mixtures ethanl-water at three different temperatures, , and K were measured and their values tabulated in Tables 1, 2 and 3. The apparent mlal vlumes (V φ ) 3,4 f NaF were calculated by using equatin (1) 5. M d d 1000 (1) Vφ = d dd m where M is the mlar mass f NaF and m is the cncentratin in mlality, d and d are the densities f

3 118 E. Gmaa, M Hamada, R Galal /Avances en Química 5 (2), (2010) slutin and mixed slvent r pure slvents, respectively. The values f V φ fr NaF at the different temperatures in the mixtures f ethanl-water are als presented in Tables 1, 2 and 3. The partial mlar vlumes V φ f sdium fluride were btained by linear extraplatin f V φ against m t infinite dilutin, fllwing the Cvingtn, equatin 6 : V V φ = φ + Sv m (2) V φ, the intercept, is the limiting value f the apparent mlal vlume and it is equal t the partial mlal vlumes at infinite dilutin. The values f V φ and the prprtinality cnstant S v (the slpe) btained frm equatin (2) are given in Table 4 with standard deviatin ranging frm 0.11 t Table 1: Apparent mlal vlumes (V φ ) in cm 3 /mle and densities (d) in g/cm 3 f different mlal cncentratins (m) fr NaF at K in ethanl-water slvents. X S (Ethanl) m d V Φ X S (Ethanl) m d V Φ x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x Table 2: Apparent mlal vlumes (V φ ) in cm 3 /mle and densities (d) in g/cm 3 f different mlal cncentratins (m) fr NaF at K in ethanl-water slvents. X S (Ethanl) m d V Φ X S (Ethanl) m d V Φ x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x

4 E. Gmaa, M Hamada, R Galal /Avances en Química 5 (2), (2010) 119 Table 3: Apparent mlal vlumes (V φ ) in cm 3 /mle and densities (d) in g/cm 3 f different mlal cncentratins (m) fr NaF at K in mixed ethanl-water slvents. X S (Ethanl) m d V Φ X S (Ethanl) m d V Φ x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x The mlar vlumes (V M ) f NaF were btained by dividing the mlar mass by the densities and their values are listed in Tables 1, 2 and 3. The packing density (P) as reprted by Kim et al. 7 and Gmaa et al. 8, i.e., the relatin between Van der Waals vlume (V w ) and the mlar vlume (V M ) f relatively large mlecules, was fund t be a cnstant value and equal t VW P = = 0.661±0.017 (3) V M The electrstrictin vlume (V e ) which is the vlume cmpressed by the slvent, was calculated by using equatin (4) 9. V e = V W - V M (4) The mlar, Van der Waals and electrstrictin vlumes f NaF in ethanl water mixtures at the three different temperatures were tabulated in Table 4. The data in Table 4 shws an increase in the values f V M and V W and decrease at the values f the third V e. A negative increase f electrstrictin values was bserved fr NaF slutins by increasing the prprtins f ethanl in the mixtures. It is bvius that the apparent mlal vlumes f electrlytes at infinite dilutin, fr vanishing in-in interactins can be cnsidered as the sum f independent inic cntributin. It means that the simple equatin 10 V φ φ + + = V (M ) V (X ) (5) φ s valid fr mnvalent mnvalent salts and divalent mnvalent salts. The study fr limiting value f the apparent mlal vlumes f electrlytes as functin f in nature, size, charge, temperature and slvent is very useful fr better understanding in-slvent interactins 11. In cmparisn f the different vlumes f sdium and fluride, like crystal vlumes 12 and Van der Waals vlumes 13, we get mean radius value fr Na + equal 0.97 Å and Å fr F. Dividing the tw tgether we get a rati f This rati can be used t split the vlume f electrlyte by it t get that f sdium in. This methd is called NaF asymmetric assumptin. Therefre, the partial mlar vlumes btained fr bth Na + and F - ins are evaluated and their values are listed in Table 5. It was bserved frm the different vlume values, that all vlumes fr the electrlyte (NaF) increased by increasing ethanl cntent in the mixed slvent due mainly t the higher slvatin. Als the electrstrictin vlumes increase in negativity cnfirming the increase in slvent effect by mre adding ethanl t the mixtures. The values f the slpes S v are negative at and K indicating dissciatin f NaF electrlyte at these temperatures. S v values are psitive at K indicating mre assciatin prcess at this temperature. Bth dissciatin and assciatin prcesses are increased by increasing the mle fractin f ethanl. S v values increase by increasing alchl percentage.

5 120 E. Gmaa, M Hamada, R Galal /Avances en Química 5 (2), (2010) Table 4: Limiting partial mlal vlume (V φ ), mlar vlumes (V M ), Van der Waals vlumes (V W ), electrstrictin vlumes (V e ) in cm 3 /mle and slpe values (S V ) fr NaF in mixed ethanl-water slvents at different temperatures K X s (Ethanl) -V φ V M V W -V e S V K X s (Ethanl) -V φ V M V W -V e S V K X s (Ethanl) -V φ V M V W -V e S V Table 5: Inic partial mlal vlumes fr Na + and F - in mixed ethanl-water slvents at different temperatures (in cm 3 /mle) K K K X s (Ethanl) -V φ (Na + ) -V φ (F - ) X s (Ethanl) -V φ (Na + ) -V φ (F - ) X s (Ethanl) -V φ (Na + ) -V φ (F - )

6 E. Gmaa, M Hamada, R Galal /Avances en Química 5 (2), (2010) 121 Cnclusins A new and simple methd fr evaluating the single in partial mlal vlumes was applied using asymmetric sdium fluride assumptin. Sdium fluride is a stable electrlyte and it is better than ptassium fluride which was used as symmetric assumptin, accrding t the unstability f the latter. 12. L Pauling. Nature f the chemical bnd. Crnell University Press, Ithaca, N.Y. (1945). 13. A Bndi. Van der Waals Vlumes and Radii. J. Phys. Chem., 68, 441 (1964). Acknwledgments Thanks t the head f Chemistry Department, Faculty f Science, Mansura University and all staff f Physical Chemistry sectin. References 1. J Krakwiak, D Bbicz, W Grzybhwski. Partial mlar vlumes f tetrabutylammnium perchlrate and tetraphenylbrate in N,N-dimethylacetamide, triethylphspha-te, acetnitrile and dimethyl sulphxide. J. Mlecular Liquids, 88, (2000). 2. D Bbicz, W Grzybkwski, A Lewandwski. Apparent mlar vlumes f divalent transitin metal chlrides and perchlrate in dimethylsulphxide slutins. J. Mlecular Liquids, 105(1), (2003). 3. S Oswal, J Desai, S Ijardar, D Jain. Studies f partial mlar vlumes f alkylamine in chlralkanes at and K. J. Mlecular Liquids, 144, (2009). 4. J.Wawer, J Krakwiak, W Grzybkwski, Apparent mlar vlumes, expansibilities and isentrpic cmpressibilities f selected electrlytes in methanl. J. Chem. Thermdynamics, 40, (2008). 5. Y Marcus. The prperties f slvents. Wiley, Lndn (1998). 6. A Cvingtn, T Dickinsn (Editrs). Physical chemistry f rganic slvent systems. Plenum Press. Lndn (1973). 7. J Kim, A Cecal, H Brn, E Gmaa. Preferential slvatin f single ins: A critical study f Ph 4 AsPh 4 B. Assumptin fr single in thermdynamics in mixed aqueus acetnitrile and aqueus N,N-dimethylfrmamide slvents. Z. Physikalische Chemie, Neue Flge, 110, (1978). 8. A El-Khuly, E Gmaa, S Abu-El-Leef. Cnductmetry and slubility studies f Cd 2+ -Kryptfix-22) cmplexes in varius hydrrganic slvents. Bulletin f Electrchemistry, 19(4), (2003). 9. A El-Khuly, E Gmaa, S Abu-El-Leef. Apparent assciatin cnstants f HgCl 2 in presence f kryptfix-22 in mixed aqueus-rganic slvents. Bulletin f Electrchemistry, 19(5), (2003). 10. K Bujnicka, E Hawlicka. Slvatin f Ca 2+ in aqueus methanl-md simulatin studies. J. Mlecular Liquids, 125, (2006). 11. R Fawcett, P Brksby, D Verbvy, I Bak, G Palinkas. Studies f anin slvatin in plar aprtic slvents. J. Mlecular Liquids, 118, (2005).

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

Partial Molar Volumes of Aluminium Chloride, Aluminium Sulphate and Aluminium Nitrate in Water-rich Binary Aqueous Mixtures of Tetrahydrofuran ORIENTAL JOURNAL OF CHEMISTRY An Internatinal Open Free Access, Peer Reviewed Research Jurnal www.rientjchem.rg ISSN: 97-2 X CODEN: OJCHEG 214, Vl. 3, N. (4): Pg. 237-241 Partial Mlar Vlumes f Aluminium