Moles?????

Water "softeners" remove metal ions such as Fe2+, Fe3+, Ca2+, and Mg2+ (which make water "hard") by replacing them with enough Na+ ions to maintain the same number of positive charges in the solution. If 6.5 103 L hard water is 0.015 M Ca2+ and 0.0010 M Fe3+, how many moles of Na+ are needed to replace these ions?

Moles?????
.033 Mol


(.015 mol Ca) * (2mol Na per mol Ca) + (.001 mol Fe * 3 mol Na per mol Fe)


to make the # moles equal out between Na+ and (Ca+Fe)