I = 1/2 × [(concentration of Na2SO4 in M × # of sodium ions × (charge of sodium)2) + (concentration of Na2SO4 in M × # of SO4 ions × (charge of SO4)2) + (concentration of KCl × # of potassium ions × (charge of potassium)2) + (concentration of KCl in M × # of chloride ions × (charge of chloride)2)]