4. Solid sodium phosphate is slowly added to 200 mL of a solution containing 0.002 mol of aluminum chloride and 0.001 mol of calcium chloride (assuming no volume change occurs). How many grams of sodium phosphate must be added to precipitate as much of one ion as possible, while the other ion just does not precipitate? What percentage of the ion that will precipitate first is still left in the solution at that time? (10pts)