Formation of Electrolyte Solutions

There are three species in the solution, and the species concentrations are defined by (1) the equilibrium constant, (2) mass balance, and (3) charge balance. 

Note that pure water, one of the most important solvents in electrochemical science and engineering, is a weak electrolyte because of its ionization  

The hydronium ion, HjO+Caq), is formed due to the reaction H20(l) + H+(aq) = HjO+Caq), the Gibbs energy of which is commonly assumed to be zero because [H+(aq) + HjOCl)] and H30 (aq) are not thermodynamically different. Therefore, the water ionization reaction can also be written as follows  

These two reactions of the water ionization are thermodynamically indistinguishable. 

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In this chapter, the properties of polar solvents are discussed, especially as they relate to the formation of electrolyte solutions. Polar solvents are arbitrarily defined here as those liquids with a relative permittivity greater than 15. Solvents with zero dipole moment and a relative permittivity close to unity are non-polar. These include benzene, carbon tetrachloride, and cyclohexane. Solvents with relative permittivities between 3 and 5 are weakly polar, and those with values between 5 and 15 are moderately polar. The latter systems are not considered in the discussion in this chapter. 

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