Electrolyte dissolution, enthalpy

The first extrapolation by a square root of concentration in Zr seems to be incorrect, because the ionic strength in these solutions is not affected by the concentration of Zr but by that of the background electrolyte. At constant ionic strength, the dissolution enthalpy should be independent of the Zr concentration. The observed concentration dependeney may indicate a change in solution speciation, hence polymer formation may have occurred. The inclusion of the data of the authors in the overall assessment of Zr hydrolysis requires a re-interpretation of their experimental data in terms of mono-mer/polymer transition. Polymer formation in similar solutions was analysed by [75TRI/SCH]. A re-interpretation was found to be important in similar solutions [75TRI/SCH] (see Appendix A entry) aceording to the reaction ... 

The quantum efficiency for solid-state devices, e.g. solar cells, is always below unity. For n-type silicon electrodes anodized in aqueous or non-aqueous HF electrolytes, quantum efficiencies above unity are observed because one or more electrons are injected into the electrode when a photogenerated hole enters the electrolyte. Note that energy conservation is not violated, due to the enthalpy of the electrochemical dissolution reaction of the electrode. 

Among other things, it became established that the nature of the structure adopted by a given compound on crystallization would then exert a profound effect on the solid-state properties of that system. For a given material, the heat capacity, conductivity, volume, density, viscosity, surface tension, diffusivity, crystal hardness, crystal shape and color, refractive index, electrolytic conductivity, melting or sublimation properties, latent heat of fusion, heat of solution, solubility, dissolution rate, enthalpy of transitions, phase diagrams, stability, hygroscopicity, and rates of reactions were all affected by the nature of the crystal structure. 

A very simple experiment that has been carried out for many electrolytes in water is the measurement of the enthalpy associated with the dissolution of the electrolyte, which is often a solid, in water. This process can be either exothermic or endothermic, and has an enthalpy change which depends on the relative amounts of electrolyte and water. By studying the enthalpy of solution for one mole of electrolyte as a function of the number of moles of water, which increase from one experiment to the next, one can determine the enthalpy of solution associated with the formation of an infinitely dilute solution. In the case of NaCl, the relevant process is... 

Ions in aqueous solutions are characterized by several thermodynamic quantities in addition to the molar volumes, heat capacities and entropies discussed above. These are the molar changes of enthalpy, entropy, and Gibbs energy on the transfer of an ion from its isolated state in the ideal gas to the aqueous solution. They pertain also to the dissolution of an electrolyte in water, since they can be considered as parts in a thermodynamic cycle in which the electrolyte is transferred to the gas phase, dissociates there into its constituent ions, which are then transferred into the solution. Contrary to thought processes, as described in Sect. 2.2., it is impossible to deal experimentally with individual ions but only with entire electrolytes or with such combinations (sums or differences) of ions that are neutral. The assignment of values to individual ions requires the splitting of the electrolyte values by some extra-thermodynamic assumption that cannot be proved or disproved within the framework of thermodynamics. However, for a theoretical estimation of the individual ionic... 

The standard molar enthalpies of dissolution of electrolytes in aqueous cosolvent mixtures are monotonic with the composition only if the cosolvent does not involve a sizable alkyl moiety in its molecules. This is the case for formamide, DMF, urea (treated as if it were a solvent), and DMSO. On the other hand, cosolvents that have a hydrophobic group and enhance the structure of the water in the water-rich region according to Marcus [16,17] show amaximum in the curve in this region... 

Both entropy and enthalpy change have to be considered when dissolving a salt in any solvent Dissolution can lead to either a positive or negative overall entropy change. In polymer electrolytes, a negative entropy of dissolution is common and can be an important consideration at higher temperatures. This effect arises because the dielectric constant of the solvent polymer (solid or liquid) is usually... 

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