Textbook Question
A volume of 18.72 mL of 0.1500 M K2Cr2O7 solution was required to titrate a sample of FeSO4 according to the equation in Problem 4.126. What is the mass of the sample?
Ch.4 - Reactions in Aqueous Solution
McMurry8th EditionChemistryISBN: 9781292336145
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Table of contents
- Ch.1 - Chemical Tools: Experimentation & Measurement170
- Ch.2 - Atoms, Molecules & Ions160
- Ch.3 - Mass Relationships in Chemical Reactions169
- Ch.4 - Reactions in Aqueous Solution199
- Ch.5 - Periodicity & Electronic Structure of Atoms102
- Ch.6 - Ionic Compounds: Periodic Trends and Bonding Theory92
- Ch.7 - Covalent Bonding and Electron-Dot Structures61
- Ch.8 - Covalent Compounds: Bonding Theories and Molecular Structure59
- Ch.9 - Thermochemistry: Chemical Energy122
- Ch.10 - Gases: Their Properties & Behavior155
- Ch.11 - Liquids & Phase Changes54
- Ch.12 - Solids and Solid-State Materials73
- Ch.13 - Solutions & Their Properties120
- Ch.14 - Chemical Kinetics98
- Ch.15 - Chemical Equilibrium125
- Ch.16 - Aqueous Equilibria: Acids & Bases110
- Ch.17 - Applications of Aqueous Equilibria147
- Ch.18 - Thermodynamics: Entropy, Free Energy & Equilibrium86
- Ch.19 - Electrochemistry154
- Ch.20 - Nuclear Chemistry96
- Ch.21 - Transition Elements and Coordination Chemistry156
- Ch.22 - The Main Group Elements187
- Ch.23 - Organic and Biological Chemistry51
Chapter 4, Problem 129
Standardized solutions of KBrO3 are frequently used in redox titrations. The necessary solution can be made by dissolving KBrO3 in water and then titrating it with an As(III) solution. What is the molar concentration of a KBrO3 solution if 28.55 mL of the solution is needed to titrate 1.550 g of As2O3? See Problem 4.128 for the balanced equation. (As2O3 dissolves in aqueous acid solution to yield H3AsO3: As2O3 + 3 H2OS 2 H3AsO3.)
Verified step by step guidance1
Identify the balanced chemical equation for the reaction between KBrO3 and H3AsO3. This will help determine the stoichiometry of the reaction.
Calculate the moles of As2O3 using its molar mass. The molar mass of As2O3 can be found by adding the atomic masses of its constituent elements.
Use the stoichiometry from the balanced equation to find the moles of KBrO3 that react with the moles of As2O3. This involves using the mole ratio from the balanced equation.
Convert the volume of the KBrO3 solution from milliliters to liters to ensure consistency in units when calculating molarity.
Calculate the molarity of the KBrO3 solution by dividing the moles of KBrO3 by the volume of the solution in liters.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Redox Reactions
Redox reactions involve the transfer of electrons between two species, resulting in changes in oxidation states. In the context of titrations, one reactant is oxidized while the other is reduced. Understanding the oxidation states of the elements involved, such as arsenic in As2O3 and bromine in KBrO3, is crucial for determining the stoichiometry of the reaction and calculating concentrations.
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Titration
Titration is a quantitative analytical technique used to determine the concentration of a solute in a solution. It involves the gradual addition of a titrant to a solution until a reaction endpoint is reached, often indicated by a color change. In this case, the volume of KBrO3 solution required to completely react with a known mass of As2O3 allows for the calculation of the molarity of the KBrO3 solution.
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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 expressed in units of moles per liter (mol/L). To find the molarity of the KBrO3 solution, one must first calculate the moles of As2O3 used in the titration and then use the volume of KBrO3 solution to determine its concentration, applying the stoichiometry from the balanced chemical equation.
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Related Practice
Textbook Question
The concentration of the Sn2+ solution used in Problem 4.130 can be found by letting it react with a known amount of Fe2+. What is the molar concentration of an Sn2+ solution if 23.84 mL is required for complete reaction with 1.4855 g of Fe2O3?
Textbook Question
Dichromate ion, Cr2O7 2-, reacts with aqueous iron(II) ion in acidic solution according to the balanced equation What is the concentration of Fe2+ if 46.99 mL of 0.2004 M K2Cr2O7 is needed to titrate 50.00 mL of the Fe2+ solution?
Textbook Question
Alcohol levels in blood can be determined by a redox reaction with potassium dichromate according to the balanced equation What is the blood alcohol level in mass percent if 8.76 mL of 0.049 88 M K2Cr2O7 is required for complete reaction with a 10.002 g sample of blood?
Textbook Question
The metal content of iron in ores can be determined by a redox procedure in which the sample is first oxidized with Br2 to convert all the iron to Fe3+ and then titrated with Sn2+ to reduce the Fe3+ to Fe2+. The balanced equation is: What is the mass percent Fe in a 0.1875 g sample of ore if 13.28 mL of a 0.1015 M Sn2+ solution is needed to titrate the Fe3+?
Textbook Question
What is the molar concentration of As(III) in a solution if 22.35 mL of 0.100 M KBrO3 is needed for complete reaction with 50.00 mL of the As(III) solution? The balanced equation is: