Primary-standard-grade arsenic(III) oxide (As₄O₆) is a useful (but carcinogenic) reagent for standardizing oxidants including MnO₄^- and I-3. To standardize MnO₄^-, As₄O₆ is dissolved in base and then titrated with MnO₄^- in acid. A small amount of iodide (I-) or iodate (IO-3 ) catalyzes the reaction between H₃AsO₃ and MnO₄^-.

As₄O₆ + 8OH^- ⇌ 4HAsO₂^3- + 2H₂O

HAsO₂³- + 2H⁺ ⇌ H₃AsO₃

5H₃AsO₃ + 2MnO^-4 + 6H⁺ → 5H₃AsO₄ + 2Mn²⁺ + 3H₂O

(a) A 3.214-g aliquot of KMnO₄ (FM 158.034) was dissolved in 1.000 L of water, heated to cause any reactions with impurities to occur, cooled, and filtered. What is the theoretical molarity of this solution if no MnO^-₄ was consumed by impurities? 

(b) What mass of As₄O₆ (FM 395.68) would be just sufficient to react with 25.00 mL of the KMnO4 solution in part (a)? 

(c) It was found that 0.146 8 g of As₄O₆ required 29.98 mL of KMnO₄ solution for the faint color of unreacted MnO₄^- to appear. In a blank titration, 0.03 mL of MnO₄^- was required to produce enough color to be seen. Calculate the molarity of the permanganate solution.