To determine the concentration of the original hydrogen peroxide solution, we need to calculate the moles of permanganate ions (MnO4-) reacting with the hydrogen peroxide.
The balanced chemical equation for the reaction between hydrogen peroxide and permanganate ions in an acidic medium is as follows:
5 H2O2 + 2 MnO4- + 6 H+ -> 5 O2 + 2 Mn2+ + 8 H2O
From the stoichiometry of the equation, we can see that 2 moles of MnO4- react with 5 moles of H2O2.
Given that 18.72 mL of the 0.021 M KMnO4 solution were required to titrate 20 mL of the diluted hydrogen peroxide solution, we can calculate the moles of MnO4- used in the titration:
Moles of MnO4- = (0.021 mol/L) x (18.72 mL / 1000 mL) = 3.93852 x 10^-4 mol
From the balanced equation, we know that 2 moles of MnO4- react with 5 moles of H2O2. Therefore, the moles of H2O2 in the 20 mL diluted solution can be calculated as follows:
Moles of H2O2 = (3.93852 x 10^-4 mol MnO4-) x (5 mol H2O2 / 2 mol MnO4-) = 9.8463 x 10^-4 mol
Now, we need to calculate the concentration of the original hydrogen peroxide solution. The 15 mL of original solution was diluted to 300 mL, which means the dilution factor is 300/15 = 20. Therefore, the concentration of H2O2 in the original sample is:
Concentration of original H2O2 = (9.8463 x 10^-4 mol / 20 mL) x (1000 mL / 1 L) = 0.04923 mol/L
Therefore, the concentration of the original hydrogen peroxide solution is 0.04923 mol/L.
The half reaction for H2O2 can be given as follows:
H2O2 -> 2H+ + 2e- + O2
In order to determine the concentration of a commercial
sample of hydrogen peroxide (H2O2
), 15 mL of it was
diluted to 300 mL. Then 20 mL of diluted solution was
acidified and titrated with a 0.021 M potassium
permanganate solution (KMnO4
). An average volume of
18.72 mL was required. Determine the concentration of
the original hydrogen peroxide. solve their half equation
1 answer