Preparation and Standardization of Potassium Permanganate Standard Solution Purposes

1417 Words Jan 19th, 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 substances
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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
2
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…