Partial molar heat capacities and volumes of transfer of some saccharides from water to aqueous urea solutions at T = 298.15 K

Banipal, P. K. ; Banipal, T. S. ; Ahluwalia, J. C. ; Lark, B. S. (2000) Partial molar heat capacities and volumes of transfer of some saccharides from water to aqueous urea solutions at T = 298.15 K The Journal of Chemical Thermodynamics, 32 (10). pp. 1409-1432. ISSN 0021-9614

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Official URL: http://linkinghub.elsevier.com/retrieve/pii/S00219...

Related URL: http://dx.doi.org/10.1006/jcht.2000.0689

Abstract

Apparent molar heat capacities φCp and volumes φV of seven monosaccharides {d( - )-ribose,d( - )-arabinose,d( + )-xylose,d( + )-glucose,d( + )-mannose,d( + )-galactose,d( - )-fructose}, seven disaccharides {sucrose,d( + )-cellobiose, lactulose,d( + )-melibiose hemihydrate,d( + )-maltose monohydrate,d( + )-lactose monohydrate,d( + )-trehalose dihydrate} and one trisaccharide {d( + )-raffinose pentahydrate} have been determined in (0.5, 1.0, 1.5, and 3.0)mol · kg -1 aqueous urea solutions at T = 298.15 K from specific heat and density measurements employing a Picker flow microcalorimeter and a vibrating-tube densimeter, respectively. By combining these data with the earlier reported partial molar heat capacitiesCp,2o and volumes V2oin water, the corresponding partial molar properties of transfer (Cp,2, tro and V2, tro) from water to aqueous urea solutions at infinite dilution have been estimated. Both the Cp,2, tro and V2,tro values have been found to be positive for all the sugars and to increase with increase in concentration of the cosolute (urea), suggesting that the overall structural order is enhanced in aqueous urea solutions. This increase in structural order has been attributed to complex formation between sugars and urea molecules through hydrogen bonding and to a decreased effect of urea on water structure. The transfer parameters have been rationalized in terms of solute-cosolute interactions using a cosphere overlap hydration model. Pair, triplet and higher-order interaction coefficients have also been calculated from transfer functions and their sign and magnitude have been discussed.

Item Type:Article
Source:Copyright of this article belongs to Elsevier Science.
Keywords:Saccharides; Heat Capacity; Volume; Interaction Coefficients; Stereochemical Effects
ID Code:357
Deposited On:21 Sep 2010 04:46
Last Modified:11 May 2011 06:59

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