J. Indian Chem. Soc., Vol. 81, October 200-1, pp. 860-864 Volun1etric and viscometric properties of urea and D-glucose in aqueous glycine at 308 K Anwar Ali*, Soghra Hyder, Shahla Khan and Saba Sabir Department of Chemistry, Jamia Millia Islamia (Central University), New Delhi-110 025, India Manuscript received 10 July 2003, revised 22 September 2003, accepted 11 May 2004 Density, viscosity and refractive index data for urea and D-glucose in (0.01, 0.02 and 0.03 M) glycine + water mixed solvent as a function of urea/glucose concentration are presented at 308 K. The density data have been used to obtain limiting ap- parent molar volume <<Pel and the slope using Masson's equation. The viscosity data are analysed by means of .Jones- Dole equation. The activation parameters of viscous flow, namely free energy of activation per mole of solvent, and free energy of activation per mole of solute, were obtained by the application of transition-state theory. The refrac- tive index was used to calculate molar rerractive index, (R 0 ) of the solutes in different solvent mixtures. All these para- meters are used to study the solute-solvent and solute-solute interactions in the mixtures used in the present investigation. Amino acids are the fundamental structural units of pro- teins and thermodynamic and viscometric propenies of these model compounds in aqueous medium provide informa- tion about solute-solvent and solute-solute interactions which in turn may help to understand several biochemical processes such as protein hydration, denaturation, aggrega- tion etc 1 • Amino acids as structural components of proteins. panicipate in all the physiological processes of a living cell 2 . The solution behaviour of urea is of considerable signifi- cance in biophysics 3 . Urea serves as an effective protein denaturant. Despite of its prominent role in biology, urea continues to intrigue and fascinate solution chemists be- cause of the curious manner in which it affects aqueous solutions 3 . Glucose is an essential constituent of blood and on reaching the tissues it is oxidised to produce C0 2 • water and energy. In view of the practical importance of the above mentioned compounds, an attempt has been made to study the solute-solvent and solute-solute interactions of urea and o-glucose in (0.01, 0.02 and 0.03 M) aqueous glycine solu- tion at 308 K. This temperature is chosen due to its close- ness to body temperature. Though there are extensive ther- modynamic studies of amino acids in water 4 , very few data are available in aqueous urea/glucose 5 solutions. In the present paper we intend to report the densities, p, viscosities, 11 and refractive indices, n 0 of (0.0 l, 0.03, 0.05, 0.07, 0.09 and 0.1 M) urea/o-glucose in (0.0 I, 0.02 and 0.03 M) glycine in water at 308 K. Experimental values of p and 11 were used to calculate the apparent molar volume. <l>v• limiting apparent molar A and B coefficients of Jones-Dole equation 6 , free energies of activation of vis- cous tlow, mole of solvent and solute re- 860 spectively. n 0 values were used to calculate molar refrac- tivity, R 0 for all the ternary solvent mixtures. These param- eters were interpreted in terms of solute-solvent and sol- ute-solute interactions in the solvent mixtures. Results and discussion Measured p, 11 and nD ofO.O l, 0.03, 0.05, 0.07, 0.09 and 0.1 M urea/glucose in (0.0 I, 0.02 and 0.03 M) glycine+ water solvents at 308 K are listed in Table I. The experi- Tuhlc 1. Densities (p). viscosities (Tl) and refractive indices (n 0 ) of urea/D-glucose in aqueous glycine as function of concentration (C) of urea/D-glucose at 308 K p T] (kg oo- 3 N m- 3 ) m 2 s) Urea+O.Ol Mglycine 0.0000 0.9942 0.7111 1.3314 0.0100 0.9942 0.7122 1.3321 0.0300 0.9945 0.7132 1.3323 0.0500 0.9950 0.7149 1.3325 0.0700 0.9953 0.7154 1.3331 0.0900 0.9956 0.7162 1.3337 0.1000 0.9957 0.7181 1.3339 Urea+ 0.02 M glycine 0.0000 0.9946 0.7122 1.3317 0.0100 0.9946 0.7130 1.3321 0.0300 0.9950 0.7138 1.3326 0.0500 0.9953 0.7155 1.3329 0.0700 0.9957 0.7157 1.3330 0.0900 0.9961 0.7164 1.3333 0.1000 0.9961 0.7166 1.3335 l1 no oo- 3 N m- 2 s) D-Glucose + 0.01 M glycine 0.9943 0.7165 1.3314 0.9944 0.7169 1.3318 0.9965 0.7264 1.3321 0.9979 0.7314 1.3325 0.9992 0.7389 1.3329 1.0005 0.7452 1.3332 1.0012 0.7538 1.3336 D-Glucose + 0.02 M glycine 0.9945 0.7238 1.3318 0.9955 0.7364 1.3321 0.9967 0.7393 1.3326 0.9979 0.7441 1.3329 0.9995 0.7512 1.3331 1.0016 0.7573 1.3337 1.0018 0.7673 1.3342