Oxalic Acid against KMnO4

Oxalic Acid against KMnO4:

For Class 12 chemistry students, mastering the intricacies of titration is a crucial step toward understanding volumetric analysis and honing laboratory skills. In this comprehensive guide, we delve into the fascinating world of volumetric titration, specifically focusing on the titration between oxalic acid and potassium permanganate (KMnO₄). This titration is not only a vital part of the chemistry curriculum but also serves as an exciting experiment that demonstrates the principles of redox reactions and quantitative analysis. Whether you’re preparing for your practical exams or seeking to reinforce your theoretical knowledge, this blog post will equip you with essential tips, step-by-step procedures, and valuable insights to ensure your practical experience is both educational and successful. Let’s unlock the secrets of titration and elevate your chemistry prowess with myetutors!

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Aim:

Prepare M/20 oxalic acid solution, and using this solution determine the strength of the given potassium permanganate (KMnO₄) solution

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Chemical Equation:

In oxalic acid against KMnO4 titration KMnO4 acts as an oxidizing agent and Oxalic acid acts as a reducing agent. The reaction occurs in an acidic medium

Indicator: KMnO₄ acts as a self indicator

End Point / Color Change: Colorless to Light Pink

In oxalic acid against KMnO4 titration till MnO₄ ^-1 ion is consumed in the solution the pink color disappears, but once MnO₄ ^1- ion is in excess they impart a pink color to the solution

Observation Table:

In oxalic acid against KMnO4 titration, the observation table is as below

Calculation:

In oxalic acid, against KMnO4 titration, the calculations are done as per the formula

a₁M₁V₁ = a₂M₂V₂

a₁ = Moles of KMnO₄  in balanced equation

M₁ = Molarity of Oxalic Acid (M/20)

V₁ = Volume of oxalic acid (Pipette volume)

a₂ = Moles of Oxalic Acid in the balanced equation

M₂ = Molarity of KMnO₄ (To find out)

V₂ = Volume of KMnO₄ [Concordant volume (16.3 mL)]

Molarity of KMnO₄

M₂ = (a₁M₁V₁)/ a₂V₂

Substitution values molarity of KMnO₄ is

M₂ = 0.0123 M

The calculation for the Strength of KMnO₄:

Strength (in g/L) = Molarity x molecular weight of KMnO₄

=  0.0123x 158 =1.938  gm /L

% Purity of KMnO₄:

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Procedure:

1.  Preparation of 0.05 M Standard Solution of Oxalic Acid
2. KMnO₄ against Oxalic Acid titration.

1. Clean the burette thoroughly, wash it with distilled water and finally rinse it with KMnO₄ solution. (Always rinse the burette with the KMnO₄ solution).
   Clamp the burette vertically in a burette stand.
2. Fill KMnO₄ solution into the burette through a funnel above the zero mark.
3. Remove the air gap, if any, from the nozzle of the burette by running the solution forcefully from the burette nozzle.
4. Remove the funnel before noting the initial reading of the burette. Also while noting the reading, see that no drop of the liquid is hanging at the nozzle of the burette.
5. Note the initial reading by keeping the eye exactly at the same level as the meniscus of the solution.
6. Pipette out 10 mL of oxalic acid solution in a washed and dried conical flask. Always wash the pipette with water and rinse with the oxalic acid (solution to be measured) before pipetting out the liquid.
7. Place the flask over the glazed tile. Titrate the acid with KMnO₄ solution
   till a very faint permanent pink color is obtained. Add KMnO₄ solution in small amounts initially and then dropwise

Result:

The strength of the given KMnO₄ solution is 3.63 gm /L

Precautions:

The precautions for oxalic acid against KMnO4 titration

1. Always rinse the burette with the solution, which is to be taken in it.
2. Remove the air gap if any, from the burette before titrating the solution. Make sure that the nozzle of the burette is also filled.
3. Never forget to remove the funnel from the burette before noting the readings of the burette and ensure that no drop is hanging from the nozzle of the burette.
4. Always read the lower meniscus for all transparent solutions and the upper meniscus for colored solutions.
5. To note the burette readings place the eye exactly at the level of the meniscus.
6. Never hold the pipette at the bulb.
7. Never use the pipette and burette with a broken nozzle.
8. Never suck a strong acid or an alkali with the pipette.
9. Always keep the lower end of the pipette dipped in the liquid while sucking the liquid.
10. Do not blow out the last drop of the solution from the jet end of the pipette into the flask.
11. The concentration (strength) of the solution must be calculated up to the fourth place of decimal.

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