The heat capacities, volumes, and expansibilities of tert-butyl alcohol – water mixtures from 6 to 65 °C

Abstract

. Can. J. Chem. 55,856 (1977). The densities and specific neat capacities of niixtures of terr-butyl alcohol (TBA) and water (W) have been measured at 6,10, 25, 40, 55, and 65 'C. From these data the apparent lnolal volilmes (O,), heat capacities j&), and expansibilities (4,) were evaluated. Generally, the tenlperature dependence of these quantities is rather characteristic of hydrophobic solutes in water. At high co~lcentrations 6, and 4,. resemble those of surfactants, suggesting the existence of some microphase separation. At low temperatures 6, show a significant hump as a function of concentration, which is probably not due to the presence of the -OH group on the TBA molecule. A similar behaviour is observed for I+,. The 4, and $c of water in TBA have also been calculated; 4,,, is in theTBA-rich region 2 to 2.5 cm3 m o l l smaller than the molar volume of water, but & , , is of the same order of magnitude as the molar heat capacity of water. InatasductionThe numerous studies on inixtures of alcohols and water have been very well reviewed by Franks and co-workers (1-3). Most of the alcoholic systems fall in a class of solutio~ls which are generally classified as typically aqueous (3-5); the excess free energy GE is positive, I TSEI > 1 HEI (entropy-controlled mixing), the solution tends to unmix at high temperatures and the concentratioii depeildence of the thermodynamic properties shotv characteristic trends. The hydrophobic character of the cosolvent seems to be responsible for the general behaviour of these solutions.fert-Butyl alcohol (TBA) is of particular interest since, although it is quite hydrophobic, it is still miscible in all proportions with water.

Fluctuating micro-heterogeneity in water–tert-butyl alcohol mixtures and lambda-type divergence of the mean cluster size with phase transition-like multiple anomalies

“…Examples of such non-ideal behavior in the binary mixture of water and amphiphilic solutes are varied and well-studied [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]. Sometimes the anomaly is strongest at surprisingly low solute concentrations.…”

The heat capacities and volumes of some low molecular weight amides, ketones, esters, and ethers in water over the whole solubility range

“…Recent work in this laboratory (1)(2)(3) has been concerned with transitions in aqueous liquid mixtures. Through heat capacity measure~nents the apparent rnolai heat capacity 4, of many simple liquids which are completely miscible in water, such as din~ethylformalnide (4), dirnetkylsulfoxide (51, and dioxane (6), decreases in a regular way from the standard (infinite dilution) partial molal heat capacity, 4,' = C,' , to the molar heat capacity of the pure organic liquid CP0.…”

Differential heats of dilution of tert-butanol into water-tert-butanol mixtures at 26.90 °C

“…A small, almost negligible, correction was applied to the H30 mixtures at low concentrations of TBA have attracted measured value of Ah to obtain the value at the unified -much attention, and there are numerous thermodynamic data I available in the literature (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14). Of these, the quantities I proportional to the second derivatives of the free energy with 1 respect to appropriate variables appear to show more pronounced features.…”

“…Of these, the quantities I proportional to the second derivatives of the free energy with 1 respect to appropriate variables appear to show more pronounced features. Examples include the concentration fluctuations (5-7), thecompressibility (8,9, 1 1), the expansibility (lo, 12), the heat capacity (10,12), and the partial molar volume (10,13). While the integral heats of mixing have been ~ determined and compiled (14), it is surprising that there appears to be no actual measurement of the differential heats of dilution in the literature.…”