Standardization of potassium permanganate (O.1N)

• 1). Weigh about 0.3g of dry sodium oxalate into a 500-mL Erlenmeyer flask.
  
  
• 2). Add 200mL of water, 50 mL of sulfuric acid (H2SO4) and 3 or 4 glass beads. Heat the solution to boiling on a hot plate.
  
  
• 3). Remove the flask from the heat and add the potassium permanganate per solution from a 50-mL Class-A burette until the first appearance of a faint pink color that holds for 30 seconds. The solution in the flask must not fall below 70*C before the endpoint is reached.
  
  
• 4). Normality of KMnO4= (WeightNa2C2O4)(2)(1000)
  
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  mL KMnO4(134)
  
  KMnO4 = potassium permanganate Na2C2O4= sodium oxalate
  
  

Determination of Hydrogen Peroxide Concentrate (30% to 70%)

• 1). Weigh a 50-mL beaker to the nearest 0.1mg. Use a Mohr pipette to add the following to the 50-mL beaker: +/- 5g of sample for 35% H2O2; +/-3.5g of sample for 50% H2O2; +/-2.5g of sample for 70% H2O2; about 20g of sample for 1% H2O2. Wear safety gloves and goggles when handling concentrated peroxide.
  
  
• 2). Re-weigh the beaker immediately to the nearest 0.1mg. Record the gain in weight as W. Transfer the sample to a 500-mL Volumetric flask containing about 250mL of water and 2 mL of H2SO4 (1:3). Rinse the beaker into the Volumetric flask. Dilute to volume with water and mix well.
  
  
• 3). Pipette 20.0 mL of the solution into a 500-mL Erlenmeyer flask containing 15 mL of H2SO4 (1:3) and 60 mL of water. Add the standardized potassium permanganate per solution from a 50-mL Class-A burette until the first appearance of a faint pink color that holds for 30 seconds. Record the volume delivered as V.
  
  
• 4). Calculation: %H2O2(w/w)=(V)(N)(1.701)(25)
  
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  W
  
  Where V= mL of potassium permanganate used in titration
  
  N= normality of potassium permanganate
  
  W= grams of sample weighed into 50-mL beaker
  
  1.701= weight per milliequivalent of H2O2 x 100
  
  25 = dilution factor