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Ch.19 - Electrochemistry
McMurry - Chemistry 8th Edition
McMurry8th EditionChemistryISBN: 9781292336145Non è quello che usi tu?Cambia libro di testo
Capitolo 19, Problema 155d

The reaction of MnO4– with oxalic acid (H2C2O4) in acidic solution, yielding Mn2+ and CO2 gas, is widely used to determine the concentration of permanganate solutions. (d) A 1.200 g sample of sodium oxalate (Na2C2O4) is dissolved in dilute H2SO4 and then titrated with a KMnO4 solution. If 32.50 mL of the KMnO4 solution is required to reach the equivalence point, what is the molarity of the KMnO4 solution?

Guida verificata passo dopo passo
1
Write the balanced chemical equation for the reaction between MnO4- and oxalic acid (H2C2O4) in acidic solution. This will help in determining the stoichiometry of the reaction.
Convert the mass of sodium oxalate (Na2C2O4) to moles using its molar mass. This step is crucial as it provides the amount of substance which reacts with the permanganate solution.
Using the stoichiometry from the balanced equation, calculate the moles of KMnO4 needed to react completely with the moles of sodium oxalate.
Convert the volume of KMnO4 solution used in the titration from mL to liters to facilitate the calculation of molarity.
Calculate the molarity of the KMnO4 solution using the formula: Molarity = Moles of solute / Volume of solution in liters.

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Stoichiometry

Stoichiometry is the calculation of reactants and products in chemical reactions based on the balanced chemical equation. It allows us to determine the relationships between the amounts of substances consumed and produced. In this case, understanding the stoichiometric ratios between KMnO4 and oxalic acid is essential for calculating the molarity of the KMnO4 solution.
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Stoichiometry Concept

Titration

Titration is a laboratory technique used to determine the concentration of a solute in a solution by reacting it with a solution of known concentration. In this scenario, the KMnO4 solution is titrated against sodium oxalate, and the volume of KMnO4 used at the equivalence point is crucial for calculating its molarity. The equivalence point indicates that the amount of titrant added is stoichiometrically equivalent to the amount of substance being analyzed.
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Acid-Base Titration

Molarity

Molarity is a measure of concentration defined as the number of moles of solute per liter of solution. It is expressed in moles per liter (mol/L). To find the molarity of the KMnO4 solution, one must calculate the number of moles of sodium oxalate used and relate it to the volume of KMnO4 solution at the equivalence point, applying the stoichiometric relationships from the balanced equation.
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