Exercise 4 | Chemical Calculations for Solutions

Calculate the ionic strength of 0.1 M solutions of Na2SO4 and MgSO4.

Ionic strength I = 12 i = 1n ci zi2


Na2SO4 → 2 Na+ + SO42-

0.1 M of Na2SO4 = 0.2 M of Na+ and 0.1 M of SO42-

I = 12 x ( 0.2 x 12 + 0.1 x (-2)) = 0.3 M


MgSO4 → Mg2+ + SO42-

0.1 M of MgSO4 = 0.1 M of Mg2+ and 0.1 M of SO42-

I = 12 x ( 0.1 x 22 + 0.1 x (-2)2 ) = 0.4 M