I. Aim: To standardize potassium permanganate solution by titration against a standard solution of oxalic acid
II. Assessment: Data Collection and Processing (DCP)
Conclusion and Evaluation (CE)
Materials:
Balance
Beakers (two 100 cm3 and one 250cm3) Burette and stand
Volumetric flask (250 cm3) Filter funnel
Storage bottle (approximately 250 cm3)] Conical flask (250 cm3)
Measuring cylinder (100 cm3) Pipette (20 cm3)
Pipette filler Distilled water
Thermometer Gloves
Bunsen, tripod and gauze mat
Potassium permanganate solution [KMnO4] 0.02 mol dm-3 provided by the teacher
Oxalic acid [H2C2O4 .2H2O] (2g)
Sulfuric acid [H2SO4] (200 cm3)
Procedure:
Preparation of Standard Oxalic Acid Solution
Calculate the mass of oxalic acid crystals required to make up 250 cm3 of 0.05 mol dm-3 solution [Safety Note: Oxalic acid is poisonous and must be handled with care. Avoid contact with oxalic acid crystals [H2C2O4 .2H2O] and solution with your skin. If contact does occur immediately wash the affected area with water]
Weigh out accurately about this amount of oxalic acid, transfer quantitatively to a 250cm3 beaker, and dissolve in about 150 cm3 of distiiled water.
Transfer this solution quantitatively to a 250 cm3 volumetric flask and dilute the solution tp 250 cm3 with distilled water.
Transfer the solution to a storage bottle, calculate the concentration and label the bottle appropriately
Standardisation of Potassium Permanganate solution
Fill a burette with the KMnO4 solution to be standardized.
Pipette 20 cm3 of the standard oxalic acid solution into a 250cm3 conical flask and add about 20 cm3 of 2 mol dm-3 of H2SO4.
Warm the conical flask to about 80 °C and titrate the permanganate solution against the oxalic acid solution. Add the KMnO4 solution fairly slowly or manganese(IV) oxide (a brown solid) may form instead of manganese(II) ion. The end point is reached when...