# Problem: 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+. Keep in mind that charge balance must be maintained.If 1600. L of hard water contains 0.021 M Ca2+ and 0.0050 M Mg2+, how many moles of Na+ is needed to replace these ions?

###### FREE Expert Solution

We are asked to determine the number of moles of Na+ needed to replace Ca2+ and Mg2+.

In order for us to solve this problem, we shall follow these steps:

Step 1: Determine the number of moles of each Ca2+ and Mg2+ using the volume of hard water.

Step 2: Perform a mole-to-mole comparison (1 mol Ca2+:2 mol charge and 1 Mg2+:2 mol charge).

Step 3: Get the total mole charge and perform a mole-to-mole comparison with Na+ ion (1 mol charge: 1 mol Na+).

We can use this similar video at Clutch as a guide:

https://www.clutchprep.com/chemistry/practice-problems/69290/hard-water-contains-ca2-mg2-and-fe2-which-interfere-with-the-action-of-soap-and-

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###### Problem Details

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+. Keep in mind that charge balance must be maintained.

If 1600. L of hard water contains 0.021 M Ca2+ and 0.0050 M Mg2+, how many moles of Na+ is needed to replace these ions?