prepare M/20 solution of oxalic acid with the help of the solution determine the molirity of given KMnO4 solution
Answers
preparation of standard solution of oxalic acid [ 250ml / M/20 ]
we know, molar mass of oxalic acid , = 126g/mol
given, molarity = 0.05M
and volume of solution , V = 250ml
so, mass of oxalic acid = M × molarity × V/1000
= 126 × 0.05 × 250/1000
= 126 × 0.05/4
= 1.575 g
now, determination of strength of using standard solution of oxalic acid.
in this titration, potassium permanganate is titrant while oxalic acid is analyte. also we observed that potassium permanganate is oxidising agent. and oxalic acid is reducing agent.The reaction between potassium permanganate and oxalic acid is carried out in an acidic medium because permanganate ion in the acidic medium is a very strong oxidizing agent. Acidity is introduced by adding dilute sulphuric acid.
The chemical reaction that takes place during titration can be represented by the chemical equation.
molecular reaction,
--------------------------------------------------------
is overall reaction.
ionic reaction,
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overall ionic redox reaction.
from balance chemical equation, it is clear that two mole of potassium permanganate reacts with five moles of oxalic acid.
according to molarity concepts ,
molarity of × volume of /molarity of oxalic acid × volume of oxalic acid = mole of /mole of oxalic acid = 2/5
so, molarity of = molarity of oxalic acid × volume of oxalic acid × 2/volume of × 5
If oxalic acid is to be titrated, add the required amount of dil. sulphuric acid and heat the flask to 60°-70°C. The purpose of heating is to increase the rate of reaction, which otherwise is slow at room temperature.