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Ch.4 - Reactions in Aqueous Solution
Brown - Chemistry: The Central Science 15th Edition
Brown15th EditionChemistry: The Central ScienceISBN: 9780137542970Not the one you use?Change textbook
All textbooksBrown 15th EditionCh.4 - Reactions in Aqueous SolutionProblem 81b
Chapter 4, Problem 81b

(b) What volume of HCl is needed to neutralize 2.87 g of Mg(OH)2?

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1
Identify the balanced chemical equation for the reaction: \[ \text{Mg(OH)}_2 + 2\text{HCl} \rightarrow \text{MgCl}_2 + 2\text{H}_2\text{O} \]
Calculate the molar mass of \( \text{Mg(OH)}_2 \) using the periodic table: \( \text{Mg} = 24.31 \text{ g/mol}, \text{O} = 16.00 \text{ g/mol}, \text{H} = 1.01 \text{ g/mol} \).
Convert the mass of \( \text{Mg(OH)}_2 \) to moles using its molar mass: \[ \text{moles of Mg(OH)}_2 = \frac{2.87 \text{ g}}{\text{molar mass of Mg(OH)}_2} \]
Use the stoichiometry from the balanced equation to find the moles of \( \text{HCl} \) needed: \[ \text{moles of HCl} = 2 \times \text{moles of Mg(OH)}_2 \]
Calculate the volume of \( \text{HCl} \) solution required using its concentration: \[ \text{Volume of HCl} = \frac{\text{moles of HCl}}{\text{concentration of HCl}} \]

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Neutralization Reaction

A neutralization reaction occurs when an acid reacts with a base to produce water and a salt. In this case, hydrochloric acid (HCl) reacts with magnesium hydroxide (Mg(OH)2) to form magnesium chloride (MgCl2) and water. Understanding this reaction is crucial for determining the stoichiometry involved in calculating the required volume of HCl.
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Stoichiometry

Stoichiometry is the calculation of reactants and products in chemical reactions based on balanced chemical equations. It allows us to determine the mole ratios of the substances involved. For this question, knowing the molar mass of Mg(OH)2 and the balanced equation for its reaction with HCl will enable us to find out how much HCl is needed to neutralize a specific mass of Mg(OH)2.
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Molarity

Molarity is a measure of concentration defined as the number of moles of solute per liter of solution. It is essential for calculating the volume of HCl required for neutralization. By knowing the molarity of the HCl solution, we can use the stoichiometric relationships from the balanced equation to find the exact volume needed to react with the given mass of Mg(OH)2.
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Related Practice
Textbook Question

(a) How many milliliters of 0.120 M HCl are needed to completely neutralize 50.0 mL of 0.101 M Ba(OH)2 solution?

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Textbook Question

Pure acetic acid, known as glacial acetic acid, is a liquid with a density of 1.049 g/mL at 25 C. Calculate the molarity of a solution of acetic acid made by dissolving 20.00 mL of glacial acetic acid at 25 C in enough water to make 250.0 mL of solution.

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Textbook Question

(b) How many milliliters of 0.125 M H2SO4 are needed to neutralize 0.200 g of NaOH?

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Textbook Question

(d) If 45.3 mL of a 0.108 M HCl solution is needed to neutralize a solution of KOH, how many grams of KOH must be present in the solution?

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