Obtain about 100 mL of iodine solution in a clean
and dry 250 mL beaker. The oven may be used to dry the beaker.
Acclimatize the buret with the iodine solution. Use three 10 mL portions
of the iodine solution to rinse the inside of the buret. The small buret funnel
should be used when transferring the iodine solution from the beaker into
Fill the buret to the 0.00 mL mark with the iodine solution.
Transfer about 50 mL of standard thiosulphate, S2O32-,
ion solution into a clean and dry 100 mL beaker.
Pipet 25.00 mL of the standard thiosulphate, S2O32-,
ion solution into a clean 250 mL erlenmeyer flask.
Add about 10 drops of starch indicator to the flask.
Add the iodine solution to the erlenmeyer flask until the blue end point
Rinse the erlenmeyer flask occasionally.
Swirl the solution until the colour end point stays.
The blue endpoint of
Read the buret carefully to determine the quantity of iodine used to reach
the end point. Record the volume of the iodine solution used.
Repeat steps 3 to 7 until two titration volumes are obtained which agree
to within +/- 0.10 mL.