Excess Quantities

Since the work of Debye and Hückel [1] every relevant theoretical treatment of electrolyte solution properties is based on the two-particle distribution function f_ij ($$ {{\vec{r}}_{1}} $$, $$ {{\vec{r}}_{2}} $$) of the ions. The pair-distribution functions show the probability of finding the ions Y_i and Y_j (equal or different ions) at positions $$ {{\vec{r}}_{1}} $$ and $$ {{\vec{r}}_{2}} $$ in the electrolyte solution, regardless of the position of all other ions and regardless of all particle velocities.