Volumes and heat capacities of some amino acids in water at 25 °C

1977 ◽  
Vol 55 (19) ◽  
pp. 3364-3367 ◽  
Author(s):  
JagDish C. Ahluwalia ◽  
Claude Ostiguy ◽  
Gerald Perron ◽  
Jacques E. Desnoyers

The apparent molal volumes and heat capacities of nine amino acids were measured in water at 25 °C with a flow densimeter and a flow microcalorimeter. It is shown that the poor additivity of the standard partial molal quantities of amino acids in water are attributable to the ionization of the two groups NH2 and COOH. The hydration of these ionic groups interfere with each other when they are separated by less than three carbon atoms.


1974 ◽  
Vol 52 (22) ◽  
pp. 3738-3741 ◽  
Author(s):  
Gérald Perron ◽  
Jacques E. Desnoyers ◽  
Frank J. Millero

The densities and volumetric specific heats of the alkaline earth chlorides have been measured in water at 25 °C in the concentration range 0.01 to 0.4 M with a flow densimeter and a flow microcalorimeter. Apparent molal volumes and heat capacities have been derived.



1975 ◽  
Vol 53 (21) ◽  
pp. 3206-3210 ◽  
Author(s):  
Nicole Desrosiers ◽  
Jacques E. Desnoyers

The apparent molal volumes and heat capacities of Bu4NBr were measured in aqueous solutions of NaF, NaCl, NaBr, KBr, NaAc, and NH4Ac at 25 °C with a flow densimeter and a flow microcalorimeter. The derived transfer functions of Bu4NBr from water to the electrolyte solutions, after correction for the long-range coulombic forces, are all negative. This suggests that the noncoulombic interactions between hydrophobic and hydrophilic ions result in negative contributions to volumes and heat capacities.





1978 ◽  
Vol 56 (1) ◽  
pp. 24-28 ◽  
Author(s):  
Alain Roux ◽  
Goolam M. Musbally ◽  
Gérald Perron ◽  
Jacques E. Desnoyers ◽  
Prem Paul Singh ◽  
...  

Measurements at 25 °C with flow calorimeters and densimeters have led to heat capacities and densities of aqueous solutions of 11 1:1 electrolytes: NaClO3, NaBrO3, NaIO3, NaNO3, NaClO4, NH4NO3, KClO3, KBrO3, KIO3, NH4Cl, and NH4ClO4. The first 6 salts were studied up to near saturation. We have used results of these measurements to obtain apparent molal heat capacities and apparent molal volumes of the various solutes. Extrapolation to infinite dilution on the basis of the Debye–Hückel theory bas led to [Formula: see text]and [Formula: see text] values for each solute. We have compared these standard values with results of earlier investigations.





1975 ◽  
Vol 53 (17) ◽  
pp. 2591-2597 ◽  
Author(s):  
Osamu Klyohara ◽  
Gérald Perron ◽  
Jacques E. Desnoyers

The densities and volumetric specific heats of p-dioxane, tetrahydropyran, morpholine, piperidine, and piperazine were measured in water at 25 °C with a flow densimeter and a flow microcalorimeter. The same properties were also determined for LiCl, NaCl, Me4NBr, and Bu4NBr at 0.1 m in dioxane–water, morpholine–water, and piperidine–water mixtures. The derived apparent molal volumes and heat capacities of the nonelectrolytes in water and the transfer functions of the electrolytes from water to the mixed solvent suggest that all the present cyclic amines and ethers are hydrophobic; the overall structural influence is very small with dioxane and large with piperidine.





1974 ◽  
Vol 52 (9) ◽  
pp. 1709-1713 ◽  
Author(s):  
Patrick R. Philip ◽  
Gérald Perron ◽  
Jacques E. Desnoyers

The apparent molal volumes and heat capacities of urea, 1,1- and 1,3-dimethylurea, and tetramethylurea were measured in H2O and D2O at 25 °C. From these data, urea–water interactions seem to cause an overall structure-breaking effect and the substituted ureas, an overall structure-making effect. The effect of the hydrogen-bonding interactions to the volume and heat capacity seems to be small compared with the intrinsic and hydrophobic contributions of a methylene group, as reflected by the isotope effect. Furthermore, transfer values seem to show a significant specificity to the degree and position of methyl substitution.





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