Calculate the % of oxalate ion in a sample of oxalate salt if it was prepared by dissolving 0.6g salt in 100 mL water and was completely oxidized by 90 mL M/100 KMn04 soln.

To determine the percentage of oxalate ion in your sample of oxalate salt, we need to follow a few logical steps involving stoichiometry and the reaction between oxalate ions and potassium permanganate (KMnO4). Let's break this down step by step.

Understanding the Reaction

The reaction between oxalate ions (C2O4^2-) and potassium permanganate in an acidic medium can be represented as follows:

5 C2O4^2- + 2 MnO4^- + 16 H^+ → 10 CO2 + 2 Mn^2+ + 8 H2O

This equation tells us that 5 moles of oxalate ions react with 2 moles of permanganate ions. This stoichiometric relationship is crucial for our calculations.

Calculating Moles of KMnO4 Used

First, we need to find out how many moles of KMnO4 were used in the reaction. The concentration of the KMnO4 solution is given as M/100, which means it is 0.01 M (since M represents molarity). The volume used is 90 mL, which we convert to liters:

• Volume in liters = 90 mL × (1 L / 1000 mL) = 0.090 L

Now, we can calculate the moles of KMnO4:

• Moles of KMnO4 = Molarity × Volume = 0.01 mol/L × 0.090 L = 0.0009 moles

Finding Moles of Oxalate Ion

Using the stoichiometry from the balanced equation, we can find the moles of oxalate ions that reacted:

• From the equation, 2 moles of KMnO4 react with 5 moles of C2O4^2-.
• Thus, the ratio is 5/2. Therefore, moles of C2O4^2- = (5/2) × moles of KMnO4.
• Moles of C2O4^2- = (5/2) × 0.0009 = 0.00225 moles.

Calculating the Mass of Oxalate Ion

Next, we need to find the mass of the oxalate ion. The molar mass of oxalate (C2O4^2-) is approximately 88 g/mol (12 g/mol for carbon and 16 g/mol for oxygen). Now, we can calculate the mass:

• Mass of C2O4^2- = moles × molar mass = 0.00225 moles × 88 g/mol = 0.198 g.

Determining the Percentage of Oxalate Ion

Finally, we can find the percentage of oxalate ion in the original sample of oxalate salt. The mass of the salt used was 0.6 g. The formula for percentage is:

• Percentage of C2O4^2- = (mass of C2O4^2- / mass of salt) × 100.
• Percentage of C2O4^2- = (0.198 g / 0.6 g) × 100 ≈ 33.0%.

Summary of Results

In conclusion, the percentage of oxalate ion in your sample of oxalate salt is approximately 33.0%. This calculation illustrates how stoichiometry and chemical reactions can be applied to determine the composition of a compound in a solution.