When ionization equilibrium is reached, the ratio of the number of ionized electrolyte molecules to its total number of molecules, expressed as a percentage. A large ionization degree means that more ions are generated by dissociation and the conductivity is strong. At a certain temperature, the ionization of an electrolyte increases as its concentration decreases. The quantitative relationship between ionization, concentration and ionization constant is determined by Ostwald’s law of dilution. Experiments have shown that weak electrolytes with very small ionization obey the dilution law well, while strong electrolytes basically do not obey the dilution law, because strong electrolytes are actually almost completely ionized. There is no power balance in solution. Because of the strong ionic interactions in strong electrolyte solutions (except in infinitely dilute solutions), the degree of ionization of strong electrolytes does not reflect the true state of their ionization. Thus, the ionization degree of strong electrolytes is called the apparent ionization degree.

2、Conductivity

The reciprocal of electrical resistance, which is consistent with the general meaning of conductivity in electrical engineering. There are two ways to express the conductance of an electrolyte solution: specific conductance and equivalent conductance. Specific conductance is the conductance of an electrolyte with 1 cm2 electrode area and 1 cm electrode distance. When two points to is the conductance of the solution containing 1 gram of equivalent electrolyte between two parallel electrodes 1 cm apart.

3、Ion trickle

When the potential gradient between the two electrodes is 1V/cm ion movement speed, also known as the absolute ion movement speed. Ion mobility decreases with increasing solution concentration and increases with increasing temperature. The greater the ionic mobility of the electrolyte, the greater the equivalent conductance.

4、Ion migration number

Some ion migration transported by the power, the fraction of the total power through the solution, also known as the ion transport fraction. The migration number of two ions with very different mobility is also very different. Industrial electrolysis, according to the size of the mobility, determine the amount of electricity conducted by the ion and the concentration changes near the electrode, as a basis for controlling the electrolysis conditions.

5、Ion activity

The corrected ion concentration, also called the effective concentration, is equal to the product of the actual ion concentration and the activity coefficient. The activity coefficient is equal to the ratio of activity to concentration. In addition to dealing with extremely dilute solutions, due to the complex interactions between the ions in solution and with the melt molecules, so that the concentration of ions is not equal to the activity, that is, the activity coefficient is not equal to 1. The introduction of the concept of ion activity, that is, the ion activity instead of ion concentration, you can only apply to the ideal solution of some thermodynamic equations can also be used in the actual solution.

6, ionic strength

The concentration of all the various ions in the solution multiplied by half of the sum of their valence squared. The average activity coefficient of ions decreases as the ionic strength increases, and the higher the valence of the ion, the more it decreases. Ionic strength to a certain extent reflects the strength of the interaction between ions.