Hard water often contains dissolved Ca2+ and Mg2+ ions. One way to soften water is to add phosphates since it form insoluble precipitates with calcium and magnesium ions. A solution is 0.035 M in calcium chloride and 0.055 M in magnesium nitrate. What mass of sodium phosphate would you add to 3.5 L of this solution to eliminate the hard water ions (assuming a complete reaction)?