Ionic Strength of a Solution

the parameter I, used to characterize the electric field of a solution of electrolytes. The ionic strength I = 1/2 Σ miZi², where Zi is the charge of ions of the given type i, and m is their molarity in the solution (that is, the number of gram-ions per kilogram of solvent). In strongly dilute solutions, certain properties of electrolytes—particularly the activity coefficient of the given strong electrolyte in the solution—depend mainly on the ionic strength of the solution, which means that their dependence on the type and concentration of other ions in the solution may be neglected in approximate calculations. [10–1 108-4]