IOSR Journal of Applied Chemistry (IOSR-JAC) e-ISSN: 2278-5736.Volume 9, Issue 10 Ver. II (October. 2016), PP 32-36 www.iosrjournals.org DOI: 10.9790/5736-0910023236 www.iosrjournals.org 32 |Page Studies on DL-Serine in Water by Volumetric and Viscometric Measurement at T=(288.15, 295.15, 302.15, 309.15, and 316.15) K. Tania Tofaz 1 , Md. Harun-Al-Rashid* 1 , Sadia Afrin 2 1 Department of Chemistry, Begum Rokeya University, Rangpur-5400, Bangladesh 2 Department of Chemistry, Jahangirnagar University, Savar, Dhaka-1342, Bangladesh Abstract: Density, ρand viscosity, η, of DL-serineaqueous solutions have been determined at (288.15, 295.15, 302.15, 309.15, and 316.15) K. The measured values of density and viscosity have been used to estimate some important parameters, such as apparent molal volume,  , limiting apparent molal volume,   0 , experimental slope, S v , second derivative of limiting apparent molal volume,  0 2 v   / 2 T  , viscosity A and B coefficients, free energy of activation, ΔG ≠ , enthalpy of activation, ΔH ≠ , entropy of activation, ΔS ≠ . Keywords: DL-serine, Apparent molar volume, activation parameters, viscosity A and B coefficients, solute- solute and solute-solvent interactions. I. Introduction Protein are the biomolecules, which play a vital role in all the biological process occurring in living organisms. Their behavior can be governed by their interactions with the surrounding environment.The study of thermodynamic stability of the native structure of proteins has proved quite challenging and still remains a subject of extensive investigation [1].Due to the complexities arising from direct thermodynamic study on proteins, investigations on the behavior of model compounds of proteins like amino acids and peptides in aqueous and mixed aqueous solvents make one to understand the factors governing the stability of the biopolymers [2, 3]. The interpretation of behavior of amino acids is quite helpful in understanding the water- protein interactions in solutions. Moreover volumetric and viscometric studies of amino acids in aqueous solutions can provide valuable information for understanding protein unfolding [4-7]. Mixed aqueous solvents are extensively used in chemistry and other fields to control factors like stability, reactivity and solubility of systems [8, 9]. In this paper, we present the volumetric and viscometric studies ofDL-serine in aqueous.Studies on densities and viscosities of amino acid solutions are of great use in characterizing the structure and properties of solutions. Various types of interactions exist between the solutes in solutions, and these solute –solute and solute–solvent interactions are of current interest in all branches of chemistry. These interactions provide a better understanding of the nature of the solute and solvent, i.e., whether the solute modifies or distorts the structure of the solvent. In the present work, we have reported that the values of density and viscosity have been measured for DL-serine. DL-serine in aqueous solution at T (288.15, 295.15, 302.15, 309.15, and 316.15) K. The relevant parameters which are related to our study such as apparent molal volume,   , limiting apparent molal volume,  0 , and its related constant, S v , second derivative of limiting apparent molal volume,  0 2 v   / 2 T  , viscosity A and B coefficients, activation parameters [free energy, ΔG ≠ , entropy, ΔS ≠ , and enthalpy, ΔH ≠ ], have been evaluated meticulously. All these parameter are used to discuss the solute-solute and solute-solvent interactions occurring in the binaryDL-serine in water system as well as the structure making/breaking tendency of DL-serine in aqueous system. II. Experimental The amino acid used in this study was DL-serine. DL-serine (purity, Mass fraction  0.99) procured from Fluka chemical company, Switzerland was used without further purification. Supplied distilled water was redistilled and deionized by passing through two ion exchange columns. The deionized water was distilled again in alkaline KMnO 4 medium and used for preparation of solution. Densities of DL-serinein aqueous solutions were measured using high precision vibrating tube digital density meter (DSA-5000 M, Anton Paar, Austria). The DSA-5000 M density is the world’s most accurate density measurement. The accuracies in density was found to be 0.000005 g∙cm -3 respectively. The method is based on the principle of time lapse measurement for certain number of oscillations of a vibrating U-shaped sample tube filled with the sample liquid. The temperature of the sample tube is controlled by two integrated in- built 100 Pt resistance thermometers to a level of highest accuracy and traceable to national standards. The temperature of the sample tube is controlled to  0.001K. Viscosities of various liquids were measured using