# I'm so stumped with this Redox Titration calculations

## Recommended Posts Hei. I need desperate help with this Redox Titration lab calculations. I suck at chemistry, I go for extra help and read text book and only understand for one day, and then I'm confused the next.

Anyways, we had to experimentally determine the % H2O2 by mass in a solution given:

MnO4 + H2O2 + H -> Mn + O2 + H2O   (charges are given).

Procedure: Combine (in order) 25 drops of H2O2 solution, 20.0 mL of deionozed water, and 20.0mL of 1.00 M +/- 0.05 M H2SO4 in an Erlenmeyer flask. Titrate with 0.0400 +/- 0.0005 M KMnO4 until solution decolorizes to a persistent pink.

Raw Data:

Mass of Erlenmeyer flask: 115.711 g

Drops of H2O2 solution: 25

Mass of Erlenmeyer flask and H2O2 (+/- 0.002) g: 117.003g

Volume of water added (+/- 0.2) mL: 20.00

Molarity of H2SO4 added (+/- 0.05) M: 1.00

Volume of H2SO4 added (+/- 0.2)mL: 20.00

Initial volume of KMnO4 added (+/- 0.2)mL: 50.00

Final volume of KMnO4 added (+/- 0.2)mL: 23.69

Molarity of KmnO4 added (+/- 0.005) M: 0.0400

Processed data:

Mass of H2O2 solution used (+/- 0.004)g:

Relative Uncertainty (+/- %)g:

Total Volume of KMnO4 used (+/- 0.04) mL:

Relative Uncertainty  (+/- %) mL:

Do I have to use the half reactions to balance the equation? How do I calculate the % mass H2O2 if I'm only given 25 DROPS?

I was going to do (Molarity H2SO4)(VOLUME H2SO4) = (MOLS H2SO4), then use stoichiometry, but I wasn't sure. I'm I in the right path?

##### Share on other sites

1) Yes balance the reaction
2) It looks like potassium permanganate is your limiting reagent (can you figure out why?) and all species are in stoichiometric ratios as presented in the balanced reaction
3) If you did the drops correctly, typically you would know the volume for each drop (eg 1 mL/drop or something).
4) Use stoichiometry to find moles of hydrogen peroxide. Then there you should be able to convert to mass ratio

• 1

## Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account. ×   Pasted as rich text.   Paste as plain text instead

Only 75 emoji are allowed.