Which of the following aqueous solutions should demonstrate the most non-ideal behavior? A. 0.1 M NaI B. 0.2 M CuSO4 C. 0.5 M KBr D. 2.0 M CuCl2 E. 2.5 M CsCl

D. 2.0 M CuCl2

Explanation:

The ionic strength of a solution shows the concentration of its ions in that given solution of the compound. Dissolved ionic compounds always dissociate into ions. The total amount of ions in solution will definitely affect the properties of the solution. The concept of ionic strength was first introduced by Lewis and Randall in 1921 while describing the activity coefficients of strong electrolytes.

The ionic strength of CuCl2 is 6M as shown:

ionic strength = 0.5*[(+2)^2*2M + (1-)^2*4M] = 6 M

The higher the ionic strength of a solution, the greater its non ideal behavior.

CuCl2 shows the greatest ionic strength hence the greatest non ideal behavior.