Determination Of The Molarity Of A Permanganate Solution Via Titration
...the use of redox titration.
Theory:
The following are the reactions that take place in the experiment:
Unbalanced: H2C2 O4 (aq) + MnO4- (aq) CO2 (g) + Mn2+(aq)
H2C2 O4 Half-Reaction: H2C2 O4 (aq) 2CO2 (g) + 2e- + 2H+(aq)
MnO4- Half-Reaction: 8H+ + 2MnO4-(aq) + 5e- Mn2+(aq) + 4H20 (l)
Net Reaction: 5H2C2 O4 (aq) + 6H+ + 2MnO4- (aq) 10CO2 (g) + 2 Mn2+(aq) +8H20 (l)
The solution was heated in order to reach better reaction rates, since the reaction occurs slowly at room temperature. Unlike many other titrations no indicator is necessary to tell the experimenter when the endpoint of the reaction is. In this case, the experimenter knows when all the oxalate has been consumed because the excess of permanganate will show up as a pink color. Thus, the permanganate ion acts as an indicator itself. The reaction produces its own catalyst in the form of Mn2+ that promotes oxidation. The sulfuric acid added to the titration flask acts as a proton donor for the solution readily giving up protons. Since the oxalic acid is not a strong acid and does not dissociate well, but is still needed in the reaction to form carbon dioxide, the addition of a strong acid, sulfuric acid, supplies the protons needed for the reaction.
Procedure:
Obtain and zero two burets, one containing .0500M oxalic acid and the other containing the permanganate solution. Next, add 25.00mL of the oxalic acid into a 250mL Erlenmeyer flask (using the bottom of the meniscus for measurements). Then proceed to measure and add 15mL of 3M sulfuric acid to the titration flask with a graduated cylinder. Heat the titration flask to a temperature of 80C. Titrate the contents of the flask with the permanganate solution. Swirl the contents of the flask after adding the permanganate and if the solution drops below 80C heat the flask...
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