Iodine-Thiosulphate Titration

Chemistry page

Equipment:

• 0.02M potassium iodate solution
• 0.5M potassium iodide solution
• 1M sulfuric acid
• Sodium thiosulphate solution
• Starch indicator solution
• Deionised water
• Pipette and filler
• Burette
• Funnel
• COnical flask
• Ahite tile
• Graduated cylinder
• Retort stand and clamp
• Beakers

Experiment:

1. Wash pipette, burette and conical flask with deionised water
2. Rinse pipette with potassium iodate and burette with iodine thiosulphate
3. Pipette 25 cm³ potassium iodate into conical flask, with 20cm³ sulphuric acid and 10cm³ potassium iodide
4. Fill burette with sodium thiosulphate. Titrate against iodine solution.
5. When colour of solution fades to pale yellow, add starch indicator. Blue-black colour appears.
6. Continue titration until colour changes from blue-black to colourless.
7. Carry out two more accurate titrations
8. Calculate concentration of thiosulphate solution.