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Ch.4 - Reactions in Aqueous Solution
Brown - Chemistry: The Central Science 14th Edition
Brown14th EditionChemistry: The Central ScienceISBN: 9780134414232Not the one you use?Change textbook
All textbooksBrown 14th EditionCh.4 - Reactions in Aqueous SolutionProblem 82d
Chapter 4, Problem 82d

(d) If 42.7 mL of 0.208 M HCl solution is needed to neutralize a solution of Ca(OH)2, how many grams of Ca(OH)2 must be in the solution?

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1
Start by writing the balanced chemical equation for the neutralization reaction between HCl and Ca(OH)2: Ca(OH)2(aq)+2HCl(aq)→CaCl(aq)2+2H(OH)(l).
Calculate the moles of HCl used in the reaction. Use the formula: moles=volume×molarity. Convert the volume from mL to L by dividing by 1000.
Using the stoichiometry from the balanced equation, determine the moles of Ca(OH)2 that reacted. According to the equation, 2 moles of HCl react with 1 mole of Ca(OH)2. Therefore, divide the moles of HCl by 2 to find the moles of Ca(OH)2.
Calculate the mass of Ca(OH)2 using its molar mass. The molar mass of Ca(OH)2 is the sum of the atomic masses of Ca, O, and H: molar mass=40.08+2×(16.00+1.01). Multiply the moles of Ca(OH)2 by its molar mass to find the mass in grams.
Ensure all units are consistent and check your calculations for accuracy. This will give you the mass of Ca(OH)2 required to neutralize the given amount of HCl.

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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 calcium hydroxide (Ca(OH)2). The balanced chemical equation for this reaction is 2 HCl + Ca(OH)2 → CaCl2 + 2 H2O, indicating that two moles of HCl are required to neutralize one mole of Ca(OH)2.
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Molarity and Volume Relationship

Molarity (M) is defined as the number of moles of solute per liter of solution. To find the number of moles of HCl used in the reaction, you can use the formula: moles = molarity × volume (in liters). In this problem, the volume of HCl is given in milliliters, so it must be converted to liters before calculating the moles.
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Stoichiometry

Stoichiometry involves using the coefficients from a balanced chemical equation to relate the amounts of reactants and products. In this case, knowing the moles of HCl allows you to determine the moles of Ca(OH)2 that reacted, and subsequently, you can convert moles of Ca(OH)2 to grams using its molar mass. This is essential for solving the problem accurately.
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Related Practice
Textbook Question

The distinctive odor of vinegar is due to acetic acid, CH3COOH, which reacts with sodium hydroxide according to: CH3COOH1aq2 + NaOH1aq2¡ H2O1l2 + NaCH3COO1aq2 If 3.45 mL of vinegar needs 42.5 mL of 0.115 M NaOH to reach the equivalence point in a titration, how many grams of acetic acid are in a 1.00-qt sample of this vinegar?

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?

Textbook Question

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

Textbook Question

(c) If 55.8 mL of a BaCl2 solution is needed to precipitate all the sulfate ion in a 752-mg sample of Na2SO4, what is the molarity of the BaCl2 solution?

Textbook Question

A 4.36-g sample of an unknown alkali metal hydroxide is dissolved in 100.0 mL of water. An acid–base indicator is added, and the resulting solution is titrated with 2.50 M HCl(aq) solution. The indicator changes color, signaling that the equivalence point has been reached, after 17.0 mL of the hydrochloric acid solution has been added. (a) What is the molar mass of the metal hydroxide?