Debye-Shocker theory
In the 1920s, Debye and Huckel proposed a theory that treats ions as a point charge and a solvent as a continuum with a specific dielectric constant. It is believed that each ion is surrounded by an ion group whose ion distribution is a spherically symmetric charge distribution called an ionic atmosphere. Therefore, Debye-Hickel theory is also called ionic atmosphere theory. They believe that the long-range force that causes the electrolyte solution to deviate from the ideal solution is the attraction between ions. The Boltzmann equation of classical statistical mechanics is used to describe the charge distribution of particles from the energy point of view. Poisson force using electrostatic theory. The process relates the potential at a point in space to the charge density. After proper simplification, the concept of ionic strength I is introduced: I= The activity coefficient equation is derived Lgγ i =-A i In the middle A= Wherein, N A is the Avogadro number; e 0 is the electron charge; ε is the dielectric constant of the liquid, and the dielectric constant value of the water can be approximately taken for the dilute solution; R is the gas constant = 8.3143 J ∕ (mol· K). A is a constant for a solvent at a defined temperature and pressure. In water at 25 ° C, ε = 78.6, A = 0.509. Individual ion activity and activity coefficients are not measurable and therefore have no thermodynamic significance, but can be correlated to measurable ion average activity. If one molecule of the binary electrolyte dissociates into a total of v, wherein v + cations, v - anions, the relationship between the average fitness coefficient γ ± and the individual ion activity coefficient is Let the valence of the ions be z + and z - respectively , then Lgγ ± =(z + lgγ ± +z - lgγ - )∕(z + +z - ) (5) thus -lgγ ± =Az + z - The Debye-Shocker theory and equations (2) and (6) are commonly referred to as Debye-Shocker's law of extremes and are suitable for very dilute solutions. It is believed that the extent to which an ion's behavior in a solvent deviates from the ideal state is determined by the solution charge density as reflected by the ionic strength, independent of the chemical nature of the ion. Debye-Shocker's Extremely Limited Law gives a lgγ ± value for a strong electrolyte dilute solution with an ionic strength between 0 and 0.005, and it is also used as a semi-empirical experience for ionic strength or complex solution expansion. The basis of theory. Spiral Rollers Spiral Rollers,159Mm Conveyor Roller,Conveyor Roller For Coal Mine,Steel Spiral Roller SHIJIAZHUANG VITURE IMPORT AND EXPORT TRADING CO.,LTD , (1)
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