Hard water contains Ca2+, Mg2+, and Fe2+, which interfere
with th...

Question

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. (a) If 1500 L of hard water contains
0.020 M Ca2+ and 0.0040 M Mg2+, how many moles of
Na+ are needed to replace these ions?

Accepted Answer

Hey everyone, we're told that water softeners are used to replace metal ions such as calcium and magnesium ions in hard water with sodium ions were asked to calculate the moles of sodium ions needed to replace these ions in five liters of hard water with 0.35 moller calcium ions and 0.11 moller magnesium ions first. Let's go ahead and calculate our calcium and magnesium ions. Starting with our calcium, we're going to take 0.035 molar, Which is moles of calcium ion over leaders. And we're going to multiply this by 5l. This will get us to 0.175 mole of our calcium ions. Next looking at our magnesium, We're going to take the same steps and we have 0. moller of our magnesium ion, which is moles over liters. And again, we're going to multiply this by five liters. This will get us to 0.55 mole of magnesium ion. Now, to calculate the moles of our sodium ion, all we need to do is take the sum of our calcium and or magnesium. So we have 0.175 mole plus 0.55 mol. And this will get us to 0.23 mol of our sodium ions so that some of our calcium and or magnesium will be replaced by our sodium. Now I hope that made sense. And let us know if you have any questions

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