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Ch.4 - Reactions in Aqueous Solution
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All textbooksBrown 14th EditionCh.4 - Reactions in Aqueous SolutionProblem 101a

Chapter 4, Problem 101a

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?

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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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Textbook 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. (b) If the sodium is added to the water softener in the form of NaCl, how many grams of sodium chloride are needed?

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Citric acid, C6H8O7, is a triprotic acid. It occurs naturally in citrus fruits like lemons and has applications in food flavouring and preservatives. A solution containing an unknown concentration of the acid is titrated with KOH. It requires 23.20 mL of 0.500 M KOH solution to titrate all three acidic protons in 100.00 mL of the citric acid solution. Write a balanced net ionic equation for the neutralization reaction.

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Textbook Question

Citric acid, C6H8O7, is a triprotic acid. It occurs naturally in citrus fruits like lemons and has applications in food flavouring and preservatives. A solution containing an unknown concentration of the acid is titrated with KOH. It requires 23.20 mL of 0.500 M KOH solution to titrate all three acidic protons in 100.00 mL of the citric acid solution. Calculate the molarity of the citric acid solution.

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