To determine the % by mass of manganese (IV) oxide in a solid sample. ( By Titration )

Procedure:
1. All instruments were washed by using deionised water.
2. 25cm3 of sodium thiosulphate solution was pipetted out and pour into a volumetric flask.
3. Deionised water was added to the graduation mark.
Part A
1. Diluted sodium thiosulphate solution with unknown concentration was poured into the burette.
2. 25cm3 of standard 0.027M iodine solution was pipetted out and pour into a conical flask.
3. The iodine solution was titrated with sodium thiosulphate solution until it became pale yellow in colour.
4. Few drops of starch as indicator were added to the solution.
5. Titration w…