A direct current of 0.125 ampere was passed through 200 milliliters of a 0.25 molar solution of Fe2(SO4)3 between platinum electrodes for a period of 1.100 hours. Oxygen gas was produced at the anode. The only change at the cathode was a slight change in the color of the solution.
At the end of the electrolysis, the electrolyte was acidified with sulfuric acid and was titrated with an aqueous solution of potassium permanganate. The volume of the KMnO4 solution required to reach the end point was 24.65 milliliters.
a. How many faradays were passed through the solution?
b. Write a balanced half-reaction for the process that occurred at the cathode during the electrolysis.
c. Write a balanced net ionic equation for the reaction that occurred during the titration with potassium permanganate.
d. Calculate the molarity of the KMnO4 solution.
2007-05-06 15:10:28 · 1 answers · asked by fkdfolf 1 in Science & Mathematics ➔ Chemistry
a) Faradays of charge = 0.125*3600*1.1/96500 = 0.00512
b) Fe3+ + e- -> Fe2+
c) MnO4- + 5Fe3+ 8H+ -> 5Fe2+ + Mn2+ + 4H2O
d) Moles of KMnO4 used = 0.00512/5 = 1.024 millmol
Molarity = 1.024/24.65 = 0.0415
2007-05-06 23:45:54 · answer #1 · answered by ag_iitkgp 7 · 1⤊ 1⤋