OCR A Jun 2010 Paper 5 Q7

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7 Redox titrations using KMnO4 in acidic conditions can be used to analyse reducing agents. Acidified KMnO4 is a strong oxidising agent, readily removing electrons: 18 MnO4+ 8H+ + 5e Mn2+ + 4H2O A student analysed a solution of hydrogen peroxide, H2O2(aq), using a redox titration with KMnO4 under acidic conditions. Under these conditions, H2O2 is a reducing agent. The overall equation for the reaction is given below. 2MnO4+ 6H+ + 5H2O2 2Mn2+ + 8H2O + 5O2 (a) Deduce the simplest whole number half-equation for the oxidation of H2O2 under these conditions. [2]OCR 2010<br />
 19 (b) The student diluted 25.0 cm3 of a solution of hydrogen peroxide with water and made the solution up to 250.0 cm3. The student titrated 25.0 cm3 of this solution with 0.0200 mol dm3 KMnO4 under acidic conditions. The volume of KMnO4(aq) required to reach the end-point was 23.45 cm3.Calculate the concentration, in g dm3, of the undiluted hydrogen peroxide solution.What volume of oxygen gas, measured at RTP, would be produced during this titration? [6] [Total: 8] END OF QUESTION PAPEROCR 2010<br />

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