Chapter 27: Problem 1

Dilute aqueous hydrogen peroxide is sold commercially to the cosmetic and health care industries as '10-Volume Hydrogen Peroxide'. This means that one volume of solution will decompose to give ten volumes of oxygen at STP. From the following analytical data calculate the concentration (\% w/v) of '10-Volume Hydrogen Peroxide'. '10-volume Hydrogen Peroxide' (25.00 \(\mathrm{mL}\) ) was dissolved in water and made up to \(250.00 \mathrm{~mL}\). This solution \((25.00 \mathrm{~mL})\) was titrated with a \(\mathrm{KMnO}_{4}\) solution ( \(48 \mathrm{~mL} ; 0.02 \mathrm{M}\) ) to a palepink end-point in the presence of dilute \(\mathrm{H}_{2} \mathrm{SO}_{4}\).

Short Answer

Expert verified

The concentration (\% w/v) of '10-Volume Hydrogen Peroxide' is 0.3264%.

Step by step solution

Calculate moles of KMnO4 used

This can be found using the molarity and volume of the KMnO4 solution used in titration. Moles of KMnO4 can be calculated using the formula Moles = Volume (L) * Molarity (M). In this case Moles = 0.048 L * 0.02 M = 0.00096 moles.

Determine the moles of hydrogen peroxide

From the balanced equation, it is clear that 2 moles of KMnO4 react with 5 moles of H2O2. Thus, using stoichiometry, we can determine the moles of hydrogen peroxide. Therefore, Moles of H2O2 = (5/2) * Moles of KMnO4 = (5/2) * 0.00096 moles = 0.0024 moles.

Determine the volume of oxygen produced

From the exercise, one volume of H2O2 decomposes to give ten volumes of Oxygen. Therefore, volume of O2 = 10 * Volume of H2O2 = 10 * 25mL = 250mL. Given that 1 mole of any gas at STP occupies 22.4L, the moles of O2 can be determined as Moles of O2 = Volume/22.4L = 250mL / 22.4L = 0.0112 moles.

Determine the percentage of H2O2

As we know that the same number of moles of O2 and H2O2 are involved in the reaction, we have 0.0024 moles of H2O2. From this the mass of H2O2 can be calculated as Mass = Moles * Molar Mass = 0.0024 moles * 34g/mole = 0.0816g. So the percentage of H2O2 will be mass of H2O2 / total mass of solution * 100% = 0.0816 g / 25 g * 100% = 0.3264%

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Short Answer

Step by step solution

Calculate moles of KMnO4 used

Determine the moles of hydrogen peroxide

Determine the volume of oxygen produced

Determine the percentage of H2O2

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