Learn about the preparation and standardization of 1M KMn04 through a laboratory experiment or practical.
Aim:
To prepare and standardize potassium permanganate (1M) using oxalic acid.
Principle:
There are several reactions in the volumetric analysis include the oxidation and reduction processes. An oxidizing agent is determined by titration with a reducing agent and vice versa. These titrations are called redox titrations. An example of redox titration is the standardization of KMnO4.
Potassium permanganate is a strong oxidizing agent and in an acidic medium, it oxidizes C2H2O4 to CO2. Because the reaction is slow at room temperature, the temperature is kept at 60° to 70° C throughout the titration or reaction. No indicator is required in this titration as KMnO4 is a self-indicator.
The molecular weight of potassium permanganate (KMn04) is 158 g/mol.
How to prepare 1m potassium permanganate solution:
Take 158.00 gm of KMnO4 and dissolve in 800 ml of distilled water in a volumetric flask, heat for 1 hour on a water bath, cool, then filter through a sintered glass filter and add enough water to make 1000 ml.
How to prepare 1M oxalic acid solution:
Take 126.07 gm of oxalic acid and dissolve in 500 ml of distilled water in a volumetric flask, and properly mixing it. Once it has completely dissolved, make up the volume to 1000 ml.
Procedure for standardization of 1M KMnO4:
Using a pipette, take 10 ml to prepare 1 M oxalic acid solution into a clean and dry conical flask, followed by 10 ml dilute H2SO4 (sulfuric acid). Titrate with KMnO4 solution after warming the contents of the flask to 70°C.
Continue titrating until you reach a faint pink color endpoint. To get accurate results, repeat the titration three times and note down the burette reading in the observation table.
Observation table:
|
Sr. No. |
Content in conical
flask
|
Burette reading |
Volume of titrant used
(ml) |
|
|
Initial |
Final |
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1 |
|
|
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2 |
|
|
|
|
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3 |
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Mean: |
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Calculations:
The formula for calculating the molarity of KMnO4 is M1V1=M2V2.
Where, V1 = Volume of 1 M C2H2O4 solution = 10.00 ml
M1 = Molarity of C2H2O4 solution = 1M
V2 = Volume of KMnO4 solution
M2 = Molarity of KMnO4 =?
Therefore: M2= M1V1 / V2
Result:
The strength of the prepared potassium permanganate solution was found to be___M.
Commonly asked questions on titration are as follows.
What is the standard used in the standardization of potassium permanganate?
Because potassium permanganate is not a primary standard, oxalic acid or sodium oxalate can be used to standardize it.
Why do we standardize potassium permanganate?
We standardize potassium permanganate to determine the strength of the prepared potassium permanganate solution by using a solution of oxalic acid as a standard.
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