First, let's calculate the number of moles of potassium permanganate (KMnO4) that reacted with the hydrogen peroxide in the 20 mL sample.
The balanced chemical equation for the reaction between hydrogen peroxide and potassium permanganate is:
5 H2O2 + 2 KMnO4 + 3 H2SO4 → 5 O2 + 2 MnSO4 + 3 H2O + K2SO4
From the equation, we can see that 2 moles of KMnO4 react with 5 moles of H2O2.
Given that the volume of the potassium permanganate solution was 0.021 M and the average volume required for titration was 18.72 mL, we can calculate the number of moles of KMnO4 used in the titration:
0.021 moles/L x 18.72 x 10^(-3) L = 0.00039312 moles
Now, using the mole ratio from the balanced equation, we find the number of moles of H2O2 in the 20 mL sample:
(5/2) x 0.00039312 = 0.0009828 moles
Next, we can calculate the concentration of H2O2 in the 20 mL sample:
Concentration = moles/volume
Concentration = 0.0009828 moles / 20 x 10^(-3) L
Concentration = 0.04914 M
Finally, we need to determine the concentration of the original hydrogen peroxide solution before dilution. Since it was diluted from 15 mL to 300 mL, the volume ratio is 1:20. Therefore, the concentration of the original hydrogen peroxide solution is:
0.04914 M x 20 = 0.9828 M
Therefore, the concentration of the original hydrogen peroxide solution is 0.9828 M.
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.
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