b. Commercial hydrogen peroxide contains small amounts of organic compounds, whi
ID: 836993 • Letter: B
Question
b. Commercial hydrogen peroxide contains small amounts of organic compounds, which are added to stabilize the hydrogen peroxide. If these compounds react with the permanganate ion, would the percent H2O2 determined be too high, too low, or remain unchanged? Explain.
c. If the pipet were wet with water prior to filling it with potassium permanganate, would the percent H2O2 determined be too high, too low, or remain unchanged? Explain.
d. If the pipet were wet with water prior to filling it with hydrogen peroxide, would the percent H2O2 determined be too high, too low, or remain unchanged? Explain.
Explanation / Answer
Balanced chemical equation:
2 KMnO4 + 5 H2O2 + 3 H2SO4 --> K2SO4 + 5 O2 + 2 MnSO4 + 8 H2O
Ionic equation:
2 MnO4- + 5 H2O2 + 6 H+ --> 5 O2 + 2 Mn2- + 8 H2O
Now, fro the above titration, the equation follows:
N1*V1 (for H2O2) = N2*V2 (for permanganate solution) ------------(1)
b. If these compounds present in H2O2 to stabilize it, react with the permanganate ion, the percent of H2O2 determined would be too low, as the amount of permananate ion left for titrating with H2O2 will be less after reaction with all the cmopounds present. Hence, perforimng titration, the estimated percent of H2O2 obtained will be less than the actual percent of H2O2 present.
c. If the pipet were wet with water prior to filling it with potassium permanganate, the percent H2O2 determined will increase since the addition of a little amount of water to the permanganate will decrease the volume of permanganate sollution taken for titration. As volume of permanganate solution taken in pippet is less ,no of moles taken is also less than desired from (balanced chemical eqatuion ). Thus it increases the percent of H2O2 to be determined as titration volume of H2O2 consumed will be less, hence using equation (1) higher is the percent of H2O2.
d. If the pipet were wet with water prior to filling it with hydrogen peroxide, the percent H2O2 determined will decrease , since additon of water in small amount to H2O2 in pippet will decrease the actual amount of H2O2 taken for titration, thus the volume of permanganate solution consumed fro titration will be less than desired. Hence, using equation (1), the percent of H2O2 will decrease.
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