A solution of potassium permanganate was standardized by titration of a solution prepared by dissolving 0.268 g of pure sodium oxalate in approximately 25 mL of distilled water.A 31.4 mL volume of titrant was required to reach the end-point.The reaction is:
2 MnO₄^- + 5 C₂O₄^2- + 16 H⁺ → 2 Mn²⁺ + 10 CO₂+ 8 H₂O
What is the molarity of MnO₄^-?

Question

Quizplus · Accepted Answer

First, let's calculate the number of moles of sodium oxalate used:

moles of Na2C2O4 = mass / molar mass
moles of Na2C2O4 = 0.268 g / 134 g/mol
moles of Na2C2O4 = 0.002 mol

The balanced equation shows that 2 moles of MnO4- react with 5 moles of Na2C2O4. Therefore, the number of moles of MnO4- used in the titration is:

moles of MnO4- = (5/2) x moles of Na2C2O4
moles of MnO4- = (5/2) x 0.002 mol
moles of MnO4- = 0.005 mol

Now we can calculate the molarity of the potassium permanganate solution:

Molarity = moles of solute / volume of solution (in L)
Molarity = 0.005 mol / 0.0314 L
Molarity = 0.159 M

Therefore, the answer is B) 0.0255 M.

A Solution of Potassium Permanganate Was Standardized by Titration of a Solution