A solution of 0.2 g of a compound containing Cu^2+ and C2 O4^2- ions on titration with 0.02 M K

step 1 Hello everyone. So the first case only C2042 minus ions oxidized by KMNO for solution. So the no

A solution of 0.2 g of a compound containing Cu^2+ and C2...

A solution of $0.2 \mathrm{~g}$ of a compound containing $\mathrm{Cu}^{2+}$ and $\mathrm{C}_{2} \mathrm{O}_{4}^{2-}$ ions on titration with $0.02 \mathrm{M} \mathrm{KMnO}_{4}$ in presence of $\mathrm{H}_{2} \mathrm{SO}_{4}$ consumes $22.6$ $\mathrm{mL}$. of the oxidant. The resultant solution is neutralized with $\mathrm{Na}_{2} \mathrm{CO}_{3}$, acidified with dil. acetic acid and treated with excess KI. The liberated iodine requires $11.3 \mathrm{~mL}$ of $0.05 \mathrm{M} \mathrm{Na}_{2} \mathrm{~S}_{2} \mathrm{O}_{3}$ solution for complete reduction. Find out the molar ratio of $\mathrm{Cu}^{2+}$ to $\mathrm{C}_{2} \mathrm{O}_{4}^{2-}$ in the compound. Write down the balanced redox reactions involved in the above titrations. [1991 - 5 Marks]

Key Concepts

Redox Titration Using Permanganate

This concept refers to the use of KMnO4 as a strong oxidizing agent in acidic solution to determine the quantity of reducing agents present. In such titrations, permanganate (MnO4?) is reduced to Mn²? while oxidizing a chosen analyte—in this case, the oxalate ion (C2O4²?)—to carbon dioxide. The reaction is characterized by a fixed stoichiometry; for example, one mole of MnO4? reacts with five moles of C2O4²? in acid. Understanding this reaction is fundamental in analytical chemistry for quantifying substances based on redox processes.

Iodometric Titration

Iodometric titration is an analytical technique where iodine, generated by the reaction of an analyte with iodide under acidic conditions, is quantitatively titrated with sodium thiosulfate. In the context of this problem, copper(II) ions react with iodide to produce iodine (and precipitate copper(I) iodide), and the amount of iodine liberated is then determined by its reduction with thiosulfate. This method is important as it provides an indirect but accurate measure of the analyte—here, the copper(II) ion—through a secondary titration process.

Stoichiometric Analysis in Redox Reactions

Stoichiometry in redox reactions involves the careful use of balanced chemical equations to relate the amounts of reactants and products. In multistep titrations, such as combining a permanganate titration for oxalate and an iodometric titration for copper, the calculated mole ratios from each reaction step are used to deduce the composition of a compound. Mastery of stoichiometric relationships is essential for determining the molar ratios of elements or ions within a compound, which in this problem leads to finding the ratio of copper(II) to oxalate ions.

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