TY - JOUR ID - TI - The Effect of Sodium Chloride on Ion Association of Lysine and Arginine Ionizable Side Chains Amino Acids with Dehydro-L-ascorbic Acid in Aqueous Solution at Different Temperatures AU - Muhammed J. Kadhim PY - 2019 VL - 60 IS - 7 SP - 1412 EP - 1422 JO - Iraqi Journal of Science المجلة العراقية للعلوم SN - 00672904 23121637 AB - Molar conductance (Λ) of ionizable side chains amino acids, lysine (Lys) andarginine (Arg) with dehydroascorbic acid (DHA) in water and in NaCl solutions wasmeasured at temperatures range 298 K to 313 K. The limited molar conductance(Λo) and the constant of the ions association (KA) are calculated using theShedlovsky techniques. The dynamic radius of the concerned ion (R) is calculatedby used Stokes–Einstein relation. The heat of association, the Gibbs free energy, thechange of entropy and activation energy (ΔHo/ kJ mol-1, ΔGo/ kJ mol-1, ΔSo/J K-1mol-1, and ΔES/ kJ mol-1) respectively), also calculated. The data show increases themolar conductance with increase in temperature and decreasing in values at additionof DHA to Lys and Arg solutions. The association ions in NaCl solutions appear toincrease in radius and decrease in diffusion coefficient relative to water solutions.ΔES, shows in most samples a positive value for the association and the values inNaCl solutions has lower relative to the water solutions. ΔGo is a trend to decreasewith an increase in DHA concentration in water and NaCl solutions. The ionassociation is exothermic reaction relative to the negative value of ΔHo. The ΔSo andΔHo results, for Lys and Arg solutions, show decreasing in values at increase inDHA concentration in water and NaCl solutions. ΔGo (kJ mol-1), ΔSo (J K-1 mol-1),ΔHo (kJ mol-1), and ΔEs (kJ mol-1)

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