Experiment 4 Online Tutorial >> Volumetric Analysis: Potassium Permanganate Titration >> Calculate Concentration Oxalic Acid

Experiment 4 - Volumetric Analysis: Potassium Permanganate Titration

Calculations for Preparing a Standard Solution

Part 1 - Calculate the concentration of oxalic acid.

In Exp #4, you will prepare 250.0 mL of the standard solution. This is achieved by first mixing an accurately-weighed amount of sodium oxalate powder with a small amount of sulfuric acid and de-ionized water in a beaker. This mixture is transferred to a 250 mL volumetric flask and de-ionized water is then added to fill the flask to the calibration line. The sodium oxalate dissolves in the acidic media to produce aqueous oxalic acid (H₂C₂O₄).

A 25.00 mL sample of the oxalic acid standard solution is then placed in an Erlenmeyer flask. The unknown solution (KMnO₄) is added from a buret until the end-point has been reached. For various reasons, best results are obtained when about 25 mL of KMnO₄ are used in this titration.

You are told that the concentration of KMnO₄ is about 0.01M and your task is to determine this concentration precisely, with 4 significant figures accuracy.

How do you ensure that the 25.00 mL sample of oxalic acid will react completely (to the end point) with about 25 mL of KMnO₄? Your first step is to answer the following question: