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Volumetric Analysis 12

The document describes an experiment to estimate the amount of oxalic acid in a 250 ml solution using potassium permanganate (KMnO4) solution. Potassium permanganate reacts with oxalic acid in an acid medium and the reaction can be used for acid-base titration. The experiment involves titrating a known volume of oxalic acid solution with 0.02M KMnO4 solution until the color changes from colorless to pale pink. The volume of KMnO4 used is then used to calculate the molarity and amount of oxalic acid present in the given solution.

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vijay kumar
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14K views

Volumetric Analysis 12

The document describes an experiment to estimate the amount of oxalic acid in a 250 ml solution using potassium permanganate (KMnO4) solution. Potassium permanganate reacts with oxalic acid in an acid medium and the reaction can be used for acid-base titration. The experiment involves titrating a known volume of oxalic acid solution with 0.02M KMnO4 solution until the color changes from colorless to pale pink. The volume of KMnO4 used is then used to calculate the molarity and amount of oxalic acid present in the given solution.

Uploaded by

vijay kumar
Copyright
© Attribution Non-Commercial (BY-NC)
Available Formats
Download as DOC or read online on Scribd
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EXPERIMENT - 12

Estimation of Oxalic Acid
Aim :­ To estimate the amount of Oxalic acid present in 250ml of given solution 
by using 0.02M KMnO4 solution.
Apparatus and Chemicals required :­

Burette, Burette stand, Pipette, Conical flask, Glazed tile, given Oxalic 

acid solution, 0.02M KMnO4 solution, Dil.H2SO4 solution 

Principle   :­  KMnO4  reacts   with  Oxalic acid in the presence of H2SO4 by   the 

following equation.
2 KMnO4 + 3H 2 SO4 + 5 H 2 C 2 O4 → K 2 SO4 + 2 MnSO4 + 10CO2 + 8 H 2 O
2 moles 5 moles

Here, 2 moles KMnO4 reacts with 5 moles H2C2O4 

Procedure :­ The solution taken in burette is given 0.02M KMnO4 solution. 20ml of given 
Oxalic acid solution is transferred into a conical flask with the help of a pipette. Then test 

tube full of Dil.H2SO4  is added to it, and then heat the solution to reach the sharp boiling 

point (Until bubbles are observed). Here no external indicator is required. Here KMnO4 acts 

as self indicator in this redox titration. This solution is titrated against 0.02M KMnO4 solution 

taken in burette. Initially the titration should be very slow. Because it is an auto catalysed 

reaction.  At the end point the colour of the solution changes from colourless to pale pink 

colour. The volume of KMnO4 run down from the burette is noted. The titrations are repeated 

till consecutive readings are obtained.

Tabular Form :­

Burette readings Volume of 
Volume of Oxalic Initial
S.No Final KMnO4 run
acid solution  in (ml) ‘a’ ml
‘b’ ml down (b-a) ml
1 20 ml

2 20 ml

3 20 ml

∴ Volume of KMnO4 solution = _______________________

VM
1 1 2 V M2
Formula :­  n = n
1 2

V1 = Volume of KMnO4 solution = ____________________ ml
M 1  = Molarity of KMnO4 solution = 0.02M

n1  = No.of moles of KMnO4 in the equation = 2 moles

V2 = Volume of Oxalic acid solution = 20 ml
M 2  = Molarity of Oxalic acid solution =?

n2  = No.of moles of Oxalic aicd in the equation = 5 moles

VM n
∴  Molarity of Oxalic acid,  M 2 = 1 1 × 2
n1 V2

V1 × 0.02 5
=  ×
2 20

= ________________ M
∴ Molarity of Oxalic acid =  M 2  = _________________ M

Amount of Oxalic acid present in 250 ml of given solution 
250
= Molarity of Oxalic acid  ×  Gram Mo1.wt. of Oxalic acid  ×  
1000
126
=  M 2 ×
4

 = ________________ grams
Report :­ 

Amount of Oxalic acid present in 250ml of given solution = _______ gms

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