Question

Calculate the ionic strength of a solution that contains 0.012 M sodium nitrate and 0.027 M magnesium chloride.

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 * ( (0.012)(1^2) + (0.012)(-1)^2 + (0.027)(2^2) + (2*0.02)(-1)^2))

IS = 0.086 M