A fertilizer railroad car carrying 129,840 L of commercial aqueous ammonia (30% ammonia by mass) tips over and spills. The density of the aqueous ammonia solution is 0.88 g/cm³. What mass of citric acid, C₆H₈O₇ (which contains three acidic protons), is required to neutralize the spill?

Name: Chemistry: The Central Science
Author: Brown
ISBN: 9780137542970

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Convert the volume of the aqueous ammonia solution from liters to cubic centimeters (cm³) using the conversion factor 1 L = 1000 cm³.

Calculate the mass of the aqueous ammonia solution using the formula: mass = volume × density. Use the density provided (0.88 g/cm³) and the volume in cm³.

Determine the mass of ammonia (NH₃) in the solution by using the percentage by mass (30%). Multiply the total mass of the solution by 0.30.

Write the balanced chemical equation for the neutralization reaction between ammonia (NH₃) and citric acid (C₆H₈O₇). Each mole of citric acid can neutralize three moles of ammonia.

Calculate the moles of ammonia using its molar mass (17.03 g/mol), then use the stoichiometry from the balanced equation to find the moles of citric acid needed. Finally, convert the moles of citric acid to mass using its molar mass (192.12 g/mol).

주요 개념

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Stoichiometry

Stoichiometry is the calculation of reactants and products in chemical reactions. It involves using balanced chemical equations to determine the proportions of substances involved. In this case, stoichiometry will help calculate how much citric acid is needed to neutralize the ammonia based on their reaction.

Acid-Base Neutralization

Acid-base neutralization is a chemical reaction where an acid reacts with a base to produce water and a salt. In this scenario, citric acid (an acid) will react with ammonia (a base) to form ammonium citrate and water. Understanding the nature of this reaction is crucial for determining the amount of citric acid required.

Concentration and Density Calculations

Concentration refers to the amount of solute in a given volume of solution, while density is the mass per unit volume of a substance. To find the mass of ammonia in the spill, one must use the density of the solution and its volume. This mass will then be used in stoichiometric calculations to find the required mass of citric acid.