Die Schule für besonders begabte SchülerInnen in Mathematik/ Naturwissenschaften/ Informatik des Großraums Leipzig

The fire washing ore "PYROLUSITE"  

Pyrolusite ore, being an impure manganese (IV) oxide, can be used to obtain elemental manganese.
To analyse a pyrolusite ore for its manganese (IV) oxide content, a 0.4118 g sample is treated with 0.7938 g ethanedioic acid dihydrate in an acidic medium. Following this reaction, the excess ethanedioic acid is titrated with potassium permanganate solution (c = 0.050 mol/l), 14.40 ml of which being required.

  1.    Describe a chemical procedure to derive manganese from pyrolusite using chemical equations as well as the English language.
  2.    Develop net ionic equations for all described reactions in the text and calculate the mass percent of manganese (IV) oxide in the ore.
  3.    Considering oxalic acid, a diprotic acid with pKa values of 1.25 and 4.275, calculate the pH increase of oxalic acid after its reaction with pyrolusite.
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