Hard water contains Ca2+, Mg2+, and Fe2+, which interfere with the action of soap and leave an insoluble coating on the insides of containers and pipes when heated. Water softeners replace these ions with Na+.
(a) If 1500 L of hard water contains 0.020 M and 0.0040 M Ca2+, how many moles of Na+ are needed to replace these ions?
(b) If the sodium is added to the water softener in the form of NaCl, how many grams of sodium chloride are needed?