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how to calculate the molarity of 30% hydrogen peroxide

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punu
India

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Topic Started by punu
on 12/26/2011 23:34 PM   
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Robo
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on 1/17/2012 9:34 AM   
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Calculation of molarity of 30% H2O2 solution

 
1. Overview
        H2O2 has been used in biological research as a source of ROS, as a inducer of apoptosis as well as in many protocols (APL enzyme reaction). H2O2 is commercially available as 30% - 40% (weight / weight) aqueous solution. Most of our biological experiments use molar concentration of H2O2, therefore, it is required to convert the % concentration to molar concentration.

2. List of important terms and formulars

    • 2.1 Percent Concentration (Weight / Weight, also called by weight)
      This can be defined as the amount of solute (in grams) present in 100 grams of solution. Following formula is used to calculate
      Percent Concentration (Weight / Weight)= 100 X Amount of solute (in grams) / Amount of solution (in grams)
    • 2.2 Percent Concentration (Weight / volume)
      This can be defined as the amount of solute (in grams) present in 100 ml of solution. Following formula is used to calculate
      Percent Concentration (Weight / volume)= 100 X Amount of solute (in grams) / Amount of solution (in ml)
    • 2.3 Density
      Density of a matter can be defined as the mass per unit volume. Following formula is used to calculate
      Density = Mass / Volume
    • 2.4 Mole
      Mole of a substance can be calculated using following formula.
      Moles = Mass of substance (in gram) / Atomic weight (Formula weight)
    • 2.5 Molarity
      Molarity can be defined as number of moles of solute present in 1 litre of solution. Molarity of a solution can be calculated using following formula.
      Molarity = Number of moles of solute/ Volume of solution (in litre)

3. Calculation

    • 3.1 Understanding the concentration terms of commercially available H2O2 solution
      If one carefully read the bottle of H2O2 or Data sheet, one may find the concentration of H2O2 written like this:
      30% H2O2 by weight
      30% H2O2 Weight / Weight
      This means 30 g of H2O2 is present in 100 g of solution (See 2.1).
    • 3.2 Calculating the volume of 100 gram of H2O2 solution
      If one carefully read the bottle of H2O2 or Data sheet, one may find the density of H2O2 solution. It is 1.11 g/ml.
      Now calculate the volume of 100 gram of H2O2 solution using formula

      Density = Weight / Volume (See 2.3)
      Volume = Weight / Density

      Density = 1.1 g/ml
      Weight = 100 g
      Volume = 100/1.1 = 90.09 ml

    • 3.3 Calculating the percentage concentration (weight/volume) of H2O2 solution
      Volume of solution = 90.09 ml
      Amount of H2O2 = 30 gram

      Formula
      Percent Concentration (Weight / volume)= 100 X Amount of solute (in grams) / Amount of solution (in ml)
      Percent Concentration (Weight / volume)= 100 X 30 / 90.09 = 33.30 gram H2O2 in 100 ml solution

    • 3.4 Calculating the moles of H2O2 present in 33.30 gm of H2O2
      Molecular weight of H2O2 = 34.01
      Amount of H2O2 = 33.30 gram

      Formula
      Moles = Mass of substance (in gram) / Atomic weight (See 2.4)
      Moles of H2O2 = 33.30 / 34.01 = 0.979 moles of H2O2
      Now we know that 0.979 moles of H2O2 is present in 100 ml solution

    • 3.5 Calculating the Molarity of H2O2 solution
      Moles of H2O2 = 0.979
      Volume of solution = 100 ml or 0.1 litre

      Formula
      Molarity = Number of moles of solute/ Volume of solution (in litre)
      Moles of H2O2 = 0.979 / 0.1 = 9.79 M

4. Result
        The Molarity of 30% H2O2 (Weight / Weight) solution (Or 33.30 % H2O2 solution (Weight / Volume) is 9.79.



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