Preparation and Standardization of Potassium Permanganate Standard Solution Purposes

1401 Words Jan 3rd, 2014 6 Pages
Experiment 5

Preparation and Standardization of

Potassium Permanganate Standard Solution
Purposes
1.To know the method of preparation and standardization of potassium permanganate standard solution.
2. To grasp the principle, the conditions and the method of permanganate titration.
3. To grasp the determination of hydrogen peroxide in hydrogen peroxide solution with permanganate method.
Principle
Permanganate titration with potassium permanganate solution (KMnO4) as standard solution is one of the oxidation-reduction titration methods. KMnO4 is a vigorous oxidant in an acidic solution, and its electrode reaction and standard electrode potential φ are as follows,
MnO4- + 8H+
Mn2+ + 4H2O φ = + l.51V
The contents of many reducible
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5
Scale about 0.2g solid KMnO4 on balance, put it in a 500mL of beaker, add 250mL of distilled water into it, heat and stir it until the solid is dissolved completely. After the solution turn co1d, pour it into a brown reagent bottle, shake it even and block it up tightly with the cork. After standing still in dark for 7~l0 days, the solution is filtered with a funnel (or draw the upper solution out of the bottle with a sucker).
Transfer the filtered solution to another clean brown reagent bottle, and put it in dark.
2. Preparation of Na2C2O4 standard solution
Precisely scale primary standard substance of Na2 C2O4 0.35~0.40g on an analytical balance, put it in a little beaker, dissolve it with about 20mL of distilled water, then transfer the solution to a 250mL volumetric flask, wash the little beaker 2~3 times with distilled water, transfer all the solution to the volumetric flask, add distilled water to the scale, and finally shake it even.
3. Standardization of KMnO4 solution

Draw 25.00mL Na2C2O2 standard solution with a pipet into an Erlenmeyer flask of
1
250mL, and add l0mL of c( H2SO4) =6molL-l solution in it, and heat it until the
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vapor rises (75 oC ~80oC), but don't make it boil. [1] During continuous shaking , titrate it with KMnO4 solution drop after drop only when the pink of the first drop fades, increasing the dropping speed gradually, but never drop KMnO4 solution in a flow[2].
When the stoichiometric point of titration
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