TY - JOUR
T1 - Effect of KCl and KNO 3 on partial molal volumes and partial molal compressibilities of some amino acids at different temperatures
AU - Riyazuddeen,
AU - Khan, Imran
PY - 2009/4
Y1 - 2009/4
N2 - Density (ρ) and ultrasonic velocity (u) values of amino acids l-alanine, l-proline, l-valine, and l-leucine in 2M aqueous KCl and 2M aqueous KNO 3 solutions have been measured as a function of amino acid concentration at different temperatures (298.15 K, 303.15 K, 308.15 K, 313.15 K, 318.15 K, and 323.15 K). Using the ρ and u data, partial molal volume ( φv) and partial molal isentropic compressibility ( φ) values have been computed. The increase in partial molal volume with temperature has been attributed to the volume expansion of hydrated zwitterions. The φ and φ values of l-alanine, l-proline, l-valine, and l-leucine in 2M aqueous KCl and KNO 3 solutions have been found to be larger than the corresponding values in water. The larger partial molal volumes of l-alanine, l-proline, l-valine, and l-leucine in 2M aqueous KCl and KNO 3 solutions have been ascribed to the formation of 'zwitterion-K +/Cl -/NO 3 - ' and 'K +/Cl -/NO 3 - -water dipole' aggregates in solutions. The formation of these entities in solutions causes the release of water associated with zwitterions to the bulk water. The larger partial molal compressibilities of l-alanine-/l-proline-/l-valine-/l-leucine-2M aqueous KCl/KNO 3 solutions than the corresponding values in water have been attributed to the formation of 'zwitterion-ion' and 'ion-water dipole' incompressible entities in solutions.
AB - Density (ρ) and ultrasonic velocity (u) values of amino acids l-alanine, l-proline, l-valine, and l-leucine in 2M aqueous KCl and 2M aqueous KNO 3 solutions have been measured as a function of amino acid concentration at different temperatures (298.15 K, 303.15 K, 308.15 K, 313.15 K, 318.15 K, and 323.15 K). Using the ρ and u data, partial molal volume ( φv) and partial molal isentropic compressibility ( φ) values have been computed. The increase in partial molal volume with temperature has been attributed to the volume expansion of hydrated zwitterions. The φ and φ values of l-alanine, l-proline, l-valine, and l-leucine in 2M aqueous KCl and KNO 3 solutions have been found to be larger than the corresponding values in water. The larger partial molal volumes of l-alanine, l-proline, l-valine, and l-leucine in 2M aqueous KCl and KNO 3 solutions have been ascribed to the formation of 'zwitterion-K +/Cl -/NO 3 - ' and 'K +/Cl -/NO 3 - -water dipole' aggregates in solutions. The formation of these entities in solutions causes the release of water associated with zwitterions to the bulk water. The larger partial molal compressibilities of l-alanine-/l-proline-/l-valine-/l-leucine-2M aqueous KCl/KNO 3 solutions than the corresponding values in water have been attributed to the formation of 'zwitterion-ion' and 'ion-water dipole' incompressible entities in solutions.
KW - Amino acid
KW - Partial molal isentropic compressibility
KW - Partial molal volume
KW - Salt
KW - Zwitterion-ion interactions
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U2 - 10.1007/s10765-008-0514-x
DO - 10.1007/s10765-008-0514-x
M3 - Article
AN - SCOPUS:63949087703
SN - 0195-928X
VL - 30
SP - 475
EP - 489
JO - International Journal of Thermophysics
JF - International Journal of Thermophysics
IS - 2
ER -