Question

By utilizing the table of activity coefficients, find the molarity of Ag⁺ in a 0.050M solution of KCl saturated with AgCl, at room temperature.

Answer 1

Recall that ionic strength considers all ions in solution, and its charges. It is typically used to calculate the ionic activity of other ions. The stronger the electrolytes, the more ionic strength they will have.

The formula:

I.S. = 1/2*sum( Ci * Zi^2)

Where

I.S. = ionic strength, M (also miu / μ ) used

Ci = concentration of ion “i”

Zi = Charge of ion “i”

The exercise:

IS = 1/2*(0.05*1 0.05*1) = 0.05

using tables

Activity coefficeint for Ag+ = 0.80

Activity coefficient for Cl- = 0.805

now..

Ksp = Activity of Ag+ * Activity of Cl-

1.8*10^-10 = ((0.80)[Ag+]) * (0.05*0.805 )

[Ag+] = (1.8*10^-10) / ((0.05*0.805 )) / 0.80

[Ag+] = 5.590*10^-9 M