Magnesium hydroxide, Mg(OH)2, is commonly used as the active ingredient in antacid tablets. A st

step 1 For this question, we're doing a neutralization between hydrochloric acid and magnesium hydroxid

Magnesium hydroxide, Mg(OH)2, is commonly used as the active...

Magnesium hydroxide, $\mathrm{Mg}(\mathrm{OH})_{2}$, is commonly used as the active ingredient in antacid tablets. A student analyzed an antacid tablet for mass percent $\mathrm{Mg}(\mathrm{OH})_{2}$ by dissolving a tablet weighing $1.462 \mathrm{~g}$ in $25.00 \mathrm{~mL}$ of $0.953 \mathrm{M} \mathrm{HCl}$, and neutralizing the unreacted HCl. That neutralization required $12.29 \mathrm{~mL}$ of $0.602 \mathrm{M} \mathrm{NaOH}$. Calculate the mass percent of $\mathrm{Mg}(\mathrm{OH})_{2}$ in the antacid tablet.

Key Concepts

Titration and Molarity

Titration is an analytical technique that involves gradually adding a titrant of known concentration to a solution of unknown concentration until the reaction reaches an endpoint. Molarity, which is the number of moles of solute per liter of solution, is used to calculate the number of moles reacting during the titration, linking measured volumes to quantitative analysis.

Mass Percent Composition

Mass percent composition is used to determine how much of a sample consists of a particular component by weight. This is calculated by dividing the mass of the component of interest by the total mass of the sample and multiplying by 100. It is a crucial concept in quality control, formulation, and verifying the concentration of active substances in mixtures.

Back Titration

Back titration is a method used when the analyte is not directly titratable or when the reaction is slow. In this method, an excess of a standard reactant is added to the sample. The surplus reagent is then titrated with another standard solution, allowing one to back-calculate the amount that reacted with the analyte, which is particularly useful in complex analytical scenarios.

Stoichiometry

Stoichiometry involves using a balanced chemical equation to determine the relative quantities of reactants and products in a chemical reaction. This concept is essential for calculating the amounts of substances that react completely based on mole ratios, as well as for determining how much of a reactant remains or is required to react with a given amount of another substance.

Acid-Base Reaction

Acid-base reactions are chemical processes where an acid and a base react to form water and a salt. Understanding these reactions is key to titration methods, as the reaction proceeds to a neutralization point where the moles of acid equal the moles of base, according to the reaction’s stoichiometry.

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