Thermodynamic Properties of Aqueous Organic Solutes in Relation to their Structure. Part II. Apparent Molal Volumes and Heat Capacities of c-Alkylamine Hydrobromides in Water

1975 ◽  
Vol 53 (5) ◽  
pp. 716-722 ◽  
Author(s):  
Carmel Jolicoeur ◽  
Jeanine Boileau ◽  
Serge Bazinet ◽  
Patrick Picker
Keyword(s):  
Heat Capacities ◽  
Group Contribution ◽  
Ring Size ◽  
Solvent Structure ◽  
Apparent Molal Volumes ◽  
Molal Volumes ◽  
The Difference ◽  
Geometrical Factors ◽  
Cyclic Compounds ◽  
Methylene Group

The density and specific heat of aqueous solutions of various c-alkylamine hydrobromides, and of n-dodecylammonium bromide, have been measured at 25 °C. The limiting apparent molal volumes [Formula: see text] and heat capacities [Formula: see text] derived from these data, are compared to the corresponding quantities for n-alkylammonium and immonium salts. The methylene group contribution to[Formula: see text] and [Formula: see text] of the cyclic compounds is generally lower than that of the linear homologs; this group contribution is also found to depend markedly on ring size, in contrast to monotonous variations found in the series of the linear compounds. The difference is suggested to originate in solvation effects in which geometrical factors (solvent structure and solute geometry) play a significant role.

Apparent Molal Volumes and Heat Capacities of Urea and Methyl-Substituted Ureas in H2O and D2O at 25 °C

1974 ◽  
Vol 52 (9) ◽  
pp. 1709-1713 ◽  
Author(s):  
Patrick R. Philip ◽  
Gérald Perron ◽  
Jacques E. Desnoyers
Keyword(s):  
Heat Capacity ◽  
Hydrogen Bonding ◽  
Heat Capacities ◽  
Breaking Effect ◽  
Methyl Substitution ◽  
Apparent Molal Volumes ◽  
Hydrogen Bonding Interactions ◽  
Molal Volumes ◽  
Methylene Group ◽  
Structure Breaking

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.

Apparent molal heat capacities and volumes of aqueous electrolytes at 25 °C: NaClO3, NaClO4, NaNO3, NaBrO3, NaIO3, KClO3, KBrO3, KIO3, NH4NO3, NH4Cl, and NH4ClO4

1978 ◽  
Vol 56 (1) ◽  
pp. 24-28 ◽  
Author(s):  
Alain Roux ◽  
Goolam M. Musbally ◽  
Gérald Perron ◽  
Jacques E. Desnoyers ◽  
Prem Paul Singh ◽  
...  
Keyword(s):  
Aqueous Solutions ◽  
Infinite Dilution ◽  
Heat Capacities ◽  
Aqueous Electrolytes ◽  
Apparent Molal Volumes ◽  
Hückel Theory ◽  
Standard Values ◽  
Molal Volumes ◽  
Apparent Molal Heat Capacities

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.

Volumes and Heat Capacities of Cyclic Ethers and Amines in Water and of some Electrolytes in these Mixed Aqueous Solvents

1975 ◽  
Vol 53 (17) ◽  
pp. 2591-2597 ◽  
Author(s):  
Osamu Klyohara ◽  
Gérald Perron ◽  
Jacques E. Desnoyers
Keyword(s):  
Mixed Solvent ◽  
Transfer Functions ◽  
Heat Capacities ◽  
Cyclic Ethers ◽  
Apparent Molal Volumes ◽  
Cyclic Amines ◽  
Specific Heats ◽  
Molal Volumes ◽  
Mixed Aqueous Solvents ◽  
Structural Influence

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.

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
Keyword(s):  
Amino Acids ◽  
Heat Capacities ◽  
Apparent Molal Volumes ◽  
Flow Microcalorimeter ◽  
Ionic Groups ◽  
The Poor ◽  
Molal Volumes

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.

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