Enthalpy of solutions

Various flow calorimeters are available connnercially. Flow calorimeters have been used to measure heat capacities, enthalpies of mixing of liquids, enthalpy of solution of gases in liquids and reaction enthalpies. Detailed descriptions of a variety of flow calorimeters are given in Solution Calorimetry by Grolier [17], by Albert and Archer [18], by Ott and Womiald [H], by Simonson and Mesmer [24] and by Wadso [25]. 

In the diagram below Ah represents the heat (enthalpy) of solution, which can be measured experimentally, and A/15 is the... 

The enthalpy of solution is quite small for many simple ionic compounds and can be either positive or negative. It is the difference between two large quantities, the sum of the hydration enthalpies and the lattice energy. 

Procedure. Calculate the heats of solution of the two species, KF and KF HOAc, at each of the four given molalities from a knowledge of the heat capacity. Calculate the enthalpy of solution per mole of solute at each concentration. Find... 

Read the article on the original research (Emsiey, 1971) and include a commentary on these results in your report for this experiment. Emsiey claims that the enthalpy of solution... 

More fundamental treatments of polymer solubihty go back to the lattice theory developed independentiy and almost simultaneously by Flory (13) and Huggins (14) in 1942. By imagining the solvent molecules and polymer chain segments to be distributed on a lattice, they statistically evaluated the entropy of solution. The enthalpy of solution was characterized by the Flory-Huggins interaction parameter, which is related to solubihty parameters by equation 5. For high molecular weight polymers in monomeric solvents, the Flory-Huggins solubihty criterion is X A 0.5. 

Physical properties of the acid and its anhydride are summarized in Table 1. Other references for more data on specific physical properties of succinic acid are as follows solubiUty in water at 278.15—338.15 K (12) water-enhanced solubiUty in organic solvents (13) dissociation constants in water—acetone (10 vol %) at 30—60°C (14), water—methanol mixtures (10—50 vol %) at 25°C (15,16), water—dioxane mixtures (10—50 vol %) at 25°C (15), and water—dioxane—methanol mixtures at 25°C (17) nucleation and crystal growth (18—20) calculation of the enthalpy of formation using semiempitical methods (21) enthalpy of solution (22,23) and enthalpy of dilution (23). For succinic anhydride, the enthalpies of combustion and sublimation have been reported (24). 

In solution, benzotriazole also exists almost exclusively as the IH tautomer 25a,c. This conclusion was drawn on the basis of early NMR [69T4667 76AHC(Sl),p. 295] and NNMR (82JOC5132 97MRC35) spectral studies and confirmed by measurements of enthalpies of solution, vaporization, sublimation, and solvation in water, methanol, and DMSO (89JA7348). 

The partial molar entropy of a component may be measured from the temperature dependence of the activity at constant composition the partial molar enthalpy is then determined as a difference between the partial molar Gibbs free energy and the product of temperature and partial molar entropy. As a consequence, entropy and enthalpy data derived from equilibrium measurements generally have much larger errors than do the data for the free energy. Calorimetric techniques should be used whenever possible to measure the enthalpy of solution. Such techniques are relatively easy for liquid metallic solutions, but decidedly difficult for solid solutions. The most accurate data on solid metallic solutions have been obtained by the indirect method of measuring the heats of dissolution of both the alloy and the mechanical mixture of the components into a liquid metal solvent.05... 

Other ordering systems show striking discrepancies with the predictions of the quasi-chemical theories. Cu-Pt,67 Co-Pt,38 and Pb-Tl36 are binaries the solid solutions of which exhibit a positive partial excess free energy for one of their components, as well as positive excess entropies of solution. Co-Pt goes even further in deviating from theory in that it has a positive enthalpy of solution,... 

We will assume that rAB = (rAA + rBB ), but we will avoid making any simplifying assumption concerning 6 (or eAB ) by calculating it from the experimental excess free energy AGe. The value of 6 so obtained is used to calculate the enthalpy of solution and TAS6. 

Thalium, excess entropy and partial molar enthalpy of solutions of noble metals in, 133... 

The enthalpy change for this process, in which we mix pure liquids, is known as an integral enthalpy of solution. 

Solution In this example, it is assumed that we add a solute to a large enough volume of solution so that the composition of the mixture does not change. The enthalpy change for this process is referred to as a differential enthalpy of solution. We can represent this process by... 

Values of mixing processes. For example, for the integral enthalpy of solution process given in Example 7.1, we used L and L2 values to show that for the process... 

Finally, they measured the enthalpy of solution of C HsO in water as a function of concentration and extrapolated to infinite dilution to get a value of -5.84 kJ-mol-1 for the reaction... 

Ais obtained from the enthalpies of solution of HCl(g) in water, extrapolated to infinite dilution. 

Randall, M. 1. 264. 265 Raoult s law 268-73 and phase equilbria 419. 423 standard state 289 Rectilinear diameters, law of 393 Redlich-Kister equation 220, 362 Redlick-K wong equation 256 relative apparent molar enthalpy of solutions 356-7... 

Benzotriazole can exist in two tautomeric forms, l-//-benzotriazole (6.46, R = H) and 2-/f-benzotriazole. If the aromatic ring contains a substituent, the 1- and 3-nitrogen atoms of the triazole are not equivalent, and therefore a 3-//-benzotri-azole derivative can also exist. The equilibrium between the 1 -H and 2-H tautomers of benzotriazoles is strongly on the side of the 1 -H tautomer, in contrast to triazole where the 2-H tautomer is dominant. Tomas et al. (1989) compared experimental data (enthalpies of solution, vaporization, sublimation, and solvation in water, methanol, and dimethylsulfoxide) with the results of ab initio theoretical calculations at the 6-31G level. 

The enthalpy of formation of PuCl3(c) is derived from the measurement of the enthalpy of solution of this compound in 6 M HC1 according to reaction (14)... 

Complex chlorides of plutonium (34, 41) do not present such a wide range of formulae as the complex fTuorides but we have at hand thermodynamic information on two important species which have also been characterized with other actinides. In table II we have disregarded the complex halides for which no thermodynamic data are available. The enthalpy of formation of Cs2NaPuClg(c) (55) and Cs2PuClg(c) (56) have been obtained from enthalpy of solution measurements."The selected (8) values are AHf(Cs2NaPuCl6,c) =... 

The enthalpy of formation of PuB c) rests on three concordant sets of data for the enthalpy of solution of this compound in 02-free 6 M HCl (66), 1 M HC1 and 0.1 M HCl (67) and comparison with the enthalpy of solution of PuCl3(c) in the same media (18). These data yield virtually identical values for the enthalpy of formation of PuBr3(c) and can be averaged as AHf(PuBr3,c) =... 

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